prompt_front: Now, answer the following question based on the text below, only give me the answer and do not output any other words.

Question: What is the security parameter for the AES-256 block cipher?

Read the following text and answer briefly.

Context 1: \section{Introduction\label{sct::intro}}
Symmetric, public-key (asymmetric) and hash-based cryptography constitute a fundamental pillar of modern cryptography  
Symmetric cryptography includes symmetric-key encryption, where a shared secret key is used for both encryption and decryption  Cryptographic hash functions map arbitrarily long strings to strings of a fixed finite length  Currently deployed public-key schemes are
used to establish a common secret key between two remote parties  They are based on factoring large numbers or solving the discrete logarithm problem over a finite group  For more details about modern cryptography the interested reader can consult one of the many excellent references on the topic, e g ~\cite{Katz:2007:IMC:1206501} 

In contrast to asymmetric schemes based on factoring or solving the discrete logarithm problem and which are completely broken by a quantum adversary via Shor's algorithm~\cite{SJC 26 1484}, symmetric schemes and hash functions are less vulnerable to quantum attacks  The best known quantum attacks against them are based on Grover's quantum search algorithm~\cite{PhysRevLett 79 325}, which offers a quadratic speedup compared to classical brute force searching  Given a search space of size $N$, Grover's algorithm finds, with high probability, an element $x$ for which a certain property such as $f(x)=1$ holds, for some function $f$ we know how to evaluate (assuming such a solution exists)  The algorithm evaluates $f$ a total of $\mathcal{O}(\sqrt{N})$ times  It applies a simple operation in between the evaluations of $f$, so the $\mathcal{O}(\sqrt{N})$ evaluations of $f$ account for most of the complexity  In contrast, any classical algorithm that evaluates $f$ in a similar ``black-box'' way requires on the order of $N$ evaluations of $f$ to find such an element 

Any quantum algorithm can be mapped to a quantum circuit, which can be implemented on a quantum computer  The quantum circuit represents what we call the ``logical layer"  Such a circuit can always be decomposed in a sequence of ``elementary 
gates", such as Clifford gates (CNOT, Hadamard etc ~\cite{NC00}) augmented by a non-Clifford gate such as the T gate 

Running a logical circuit on a full fault-tolerant quantum computer is highly non-trivial  The sequence of logical gates have to be mapped to 
sequences of surface code measurement cycles (see e g ~\cite{PhysRevA 86 032324} for extensive details)  By far, the most resource-consuming (in 
terms of number of qubits required and time) is the T gate\footnote{Clifford gates are ``cheap", i e  they require relatively small overhead for implementation in the surface code, but are not universals, hence a non-Clifford gate is required  One such gate is the T gate  There are other possible choices, however all of the non-Clifford gates require special techniques such as magic state distillation~\cite{1367-2630-14-12-123011,PhysRevA 86 052329} and significant overhead (order of magnitudes higher than Clifford gates) to be implemented in the surface code  In fact, to a first order approximation, for the purpose of resource estimation, one can simply ignore the overhead introduced by the Clifford gates and simply focus only on the T gates }  
In comparison with surface code defects and braiding techniques~\cite{PhysRevA 86 032324}, novel lattice surgery 
techniques~\cite{2018arXiv180806709F,1808 02892,1367-2630-14-12-123011} reduce the spatial overhead required for implementing T gates via magic state distillation by approximately a factor of 5, while also modestly improving the running time  

In this paper we first analyze the security of symmetric schemes and hash functions against large-scale fault-tolerant quantum adversaries, using surface code defects and braiding techniques  We take into account the time-space trade-offs with parallelizing quantum search, down to the fault-tolerant layer  Naively, one might hope that $K$ quantum computers (or quantum ``processors'', as we will call them later in the paper) running in parallel reduce the number the circuit depth down to $\mathcal{O}(\sqrt{N})/K$ steps, similar to the classical case of distributing a search space across $K$ classical processors  However quantum searching does not parallelize so well, and the required number of steps
for parallel quantum searching is of the order $\mathcal{O}(\sqrt{N/K})$~\cite{quantph 9711070}  This is a factor of $\sqrt{K}$ larger than $\mathcal{O}(\sqrt{N})/K$   As shown in~\cite{quantph 9711070}, the optimal way of doing parallel quantum search is to partition the search space into $N/K$ parts, and to perform independent quantum searches on each part 

Secondly, we investigate the security of public-key cryptographic schemes such as RSA and ECC against 
quantum attacks, using the latest developments in theory of fault-tolerant quantum error correction, i e  novel lattice surgery 
techniques~\cite{2018arXiv180806709F,1808 02892,1367-2630-14-12-123011} 

The remainder of this paper is organized as follows  In Sec ~\ref{sct::method}, we provide an overview of the methodology used in our analysis  In Sec ~\ref{sct::ciphers} we investigate the security of the AES family of modern symmetric ciphers  In Sec ~\ref{sct::hash} we analyze the security of the SHA family of hash functions  In Sec ~\ref{sct::bitcoin} we investigate the security of Bitcoin's~\cite{satoshi:bitcoin} proof-of-work consensus mechanism  We conclude our investigation of symmetric and hash-based cryptographic schemes in Sec ~\ref{sct::intrinsic_parallel_grover}, where we evaluate the intrinsic cost of running the Grover algorithm with a trivial oracle (i e , an oracle with a unit cost of 1 for each invocation) 

In the subsequent sections  we analyze public-key cryptographic schemes  In Sec ~\ref{sct::rsa} and Sec ~\ref{sct::ecc} we examine the most common public-key establishment schemes, such as RSA and ECC, respectively  In the subsequent sections  we analyze public-key cryptographic schemes  In Sec ~\ref{sct::rsa} and Sec ~\ref{sct::ecc} we examine the most common public-key establishment schemes, such as RSA and ECC, respectively  Finally we summarize our findings and conclude in Sec ~\ref{sct::conclusion} 
\section{Methodology\label{sct::method}}

\subsection{Symmetric cryptography and hash functions\label{sct::symmetric}}
The methodology, sketched in Fig ~\ref{fgr:flowchart_lite} and Fig ~\ref{fgr:full_algorithm}, follows the same lines as the one described in great detail in our earlier paper~\cite{10 1007/978-3-319-69453-5_18}, which we refer the interested reader to for more details 
\begin{figure}[htb]
	\centering
         \includegraphics[width=0 35\textwidth]{figures/flowchart_lite pdf}
         \caption{Analyzing an attack against a symmetric cryptographic function with a fault-tolerant quantum adversary  Our resource estimation methodology takes into account several of the layers between the high level description of an algorithm and the physical hardware required for its execution  Our approach is modular should assumptions about any of these layers change, and hence it allows one to calculate the impact of improvements in any particular layer }
         \label{fgr:flowchart_lite}
\end{figure}
\begin{figure}
	\centering
	 \includegraphics[width=0 46\textwidth]{figures/grover_vertical pdf}
          \caption{Grover searching with an oracle for $f : \{0,1\}^k \rightarrow \{0,1\}^k$  The algorithm makes $\lfloor \frac{\pi}{4} 2^{N/2}\rfloor$ calls to
$G$, the \emph{Grover iteration}, or, if parallelized on $K$ processors, $\lfloor \frac{\pi}{4} 2^{N/(2K)}\rfloor$ calls to $G$  The Grover iteration has two
subroutines  The first, $U_g$, implements the predicate $g : \{0,1\}^k
\rightarrow \{0,1\}$ that maps $x$ to $1$ if and only if $f(x) = y$  Each call to $U_g$ involves two calls to a reversible implementation of $f$ and one call to a comparison circuit that checks whether $f(x) = y$ }
          \label{fgr:full_algorithm}
\end{figure}

We assume a surface-code based fault-tolerant architecture~\cite{PhysRevA 86 032324}, using Reed-Muller distillation schemes~\cite{Fowler:2013aa}  For each scheme we vary the possible physical error rates per gate from $10^{-4}$ to $10^{-7}$  We believe that this range of physical error rates is wide enough to cover both first generation quantum computers as well as more advanced future machines 
In comparison to surface code defects and braiding methods~\cite{PhysRevA 86 032324}, lattice surgery 
techniques~\cite{2018arXiv180806709F,1808 02892,1367-2630-14-12-123011} mostly impact the physical footprint of the fault-tolerant layer required to run a specific quantum algorithm, reducing the distillation overhead by approximately a factor of 5  The temporal overhead (i e  the number of surface code cycles) is reduced less drastically  For this reason, lattice surgery has less significant effects in estimating the security of symmetric schemes or hash functions, reducing the security parameter\footnote{The security parameter is defined as the logarithm base two of the number of fundamental operations (in our case surface code cycles) required to break the scheme } by at most 1 and decreasing the spatial overhead by at most a factor of 5  Therefore when estimating the security of symmetric and hash-based cryptographic schemes we use surface code defects and braiding techniques 

For each cryptographic primitive, we display four plots, in the following order:
\begin{enumerate}
\item We plot the total number of surface code cycles per CPU (where a CPU is a quantum computer capable of executing a single instance of Grover's quantum search algorithm) as a function of the number of CPUs  We directly tie the quantum security parameter to the total number of surface code cycles (see~\cite{10 1007/978-3-319-69453-5_18} for more details)  We also add to the plot the theoretical lower bound achievable by quantum search in the cases of: a) considering the oracle a black box of unit cost (lower line), and b) considering the oracle as composed of ideal quantum gates, each of unit cost (upper line)  Note that the difference between b) and a) represents the intrinsic cost of logical overhead (i e  the overhead introduced by treating the oracle as a logical circuit and not a blackbox), whereas the difference between the upper lines and b) represents the intrinsic cost introduced by the fault-tolerant layer 

\item We plot the total wall-time per CPU (i e  how long will the whole computation take on a parallel quantum architecture) as a function of the number of CPUs  The horizontal dashed line represents the one-year time line, i e  the $x$ coordinate of the intersection point between the ``Total time per CPU'' line and the one-year time line provides the number of processors required to break the system within one year (in $\log_2$ units) 

\item We plot the total physical footprint (number of qubits) per CPU, as a function of the number of CPUs 
\item Finally we plot the total physical footprint (number of qubits) of all quantum search machines (CPUs) running in parallel 
\end{enumerate}

In the following sections we proceed to analyze symmetric ciphers (AES, Sec ~\ref{sct::ciphers}), hash functions (SHA-256, SHA3-256, Sec ~\ref{sct::hash}, Bitcoin's hash function, Sec ~\ref{sct::bitcoin}), and finally the minimal resources required for running Grover's algorithm with a trivial oracle~\ref{sct::intrinsic_parallel_grover} (e g  the identity gate) on search spaces of various sizes 

Note that in some ranges of the plots from sections~\ref{sct::ciphers},~\ref{sct::hash},~\ref{sct::intrinsic_parallel_grover} and~\ref{sct::bitcoin} the total physical footprint increases slightly with the number of processors, which may seem counter-intuitive  This happens due to the fact that with more processors the required code distances decrease, and in some instances one can pipeline more magic states factories in parallel into the surface code, which in effect causes an increase in the overall physical footprint  Note that the total time per CPU is monotonically decreasing, as parallelizing distilleries does not increase the wall time  For more details see~\cite{10 1007/978-3-319-69453-5_18}  

\subsection{Public-key cryptography\label{sct::pk}}

Most of the recent progress in quantum cryptanalysis is related to the fault-tolerant layer in Fig ~\ref{fgr:flowchart_lite}  New methods and techniques
based on surface code lattice surgery~\cite{2018arXiv180806709F,1808 02892,1367-2630-14-12-123011} allow a significant decrease of the overall 
footprint (number of qubits, or space) taken by the quantum computation, and also a relatively modest decrease in time, in comparison with  methods based on surface code defects and braiding~\cite{PhysRevA 86 032324,Fowler:2013aa} 

We consider the best up-to-date optimized logical quantum circuits for attacking RSA and ECC public-key 
schemes~\cite{1706 06752,PhysRevA 52 3457,cuccaro04,Beauregard:2003:CSA:2011517 2011525} then perform a physical footprint resource estimation
analysis using lattice surgery techniques  We remark that the overall time required to run the algorithm depends on the level of parallelization 
for the magic state factories\footnote{Every T gate in the circuit must be implemented by a specialized magic state factory, each of which occupies a 
significant physical footprint  One can implement more magic states in parallel if one is willing to increase the physical footprint of the computation }  

For each public-key cryptogrpric scheme, we analyze the space/time tradeoffs and plot the results on a double logarithmic scale  We fit the data using a third degree 
polynomial\footnote{A third degree polynomial fits the data very precisely, providing a coefficient of determination $R^2$ greater than 0 997 } and obtain an analytical closed-form formula for the relation between the time and the number of qubits required to attack the scheme, in 
the form

\begin{equation}\label{eqn1}
y(x) = \alpha x^3 + \beta x^2 + \gamma x + \delta,
\end{equation}
where $y$ represents logarithm base 2 of the number of qubits and $x$ represents the logarithm base 2 of the time (in seconds)  For example,
the quantity 
\begin{equation}\label{eqn2}
y\left(\log_2(24\times 3600)\right) \approx y(16 3987)
\end{equation}
represents how many qubits are required to break the scheme in one day (24 hours) for a fixed physical error rate per gate $p_g$, assuming a 
surface code cycle time of 200ns  Note that the computation time scales linearly with the surface code cycle time, e g  a 1000ns surface code cycle 
time will result in a computation that is 5 times longer than a $200ns$ surface code cycle time  Therefore, for a specific cryptographic scheme for 
which we plotted the space/time tradeoffs using a surface code cycle time of $200ns$ and a fixed physical error rate per gate $p_g$, the number of 
qubits required to break a specific scheme in a time $t$ using an alternative surface code cycle time $t_c$ is given by

\begin{equation}\label{eqn3}
y\left(\log_2\left(\frac{200ns}{t_c}t\right)\right),
\end{equation}
where $t$ is expressed in seconds and $t_c$ is expressed in nanoseconds 

We assume a surface code cycle time of 200ns, in conformance with~\cite{PhysRevA 86 032324}  For each scheme we analyze, we compare its security using the more conservative (and realistic in the short term) $p_g=10^{-3}$ and also the more optimistic  $p_g=10^{-5}$  Note that assuming the more optimistic assumption from a quantum computing perspective is the more conservative assumption from a cybersecurity perspective 

Furthermore, in this analysis, we are reporting the full physical footprint, including the memory required for magic state distillation 
Using present-day techniques, the memory required for generating these generic input states accounts for a substantial fraction of the total memory cost and thus we are including these in the total cost estimate and will track the impact of improved methods 

\section{Symmetric ciphers\label{sct::ciphers}}
Below we analyze the security of AES family of symmetric ciphers against large-scale fault-tolerant quantum adversaries  We used the highly optimized logical circuits produced in
\cite{10 1007/978-3-319-29360-8_3}  

\subsection{AES-128}

        \includegraphics[width=0 429\textwidth]{figures/AES-128_cycles pdf}
      	\captionof{figure}{AES-128 block cipher  Required surface clock cycles per processor, as a function of the  number of processors ($\log_2$ scale)  The bottom brown line (theoretical lower bound, black box) represents the minimal number of queries required
	by Grover's algorithm, the cost function being the total number of queries to a black-box oracle, each query assumed to have unit cost, and a completely error-free circuit  The purple line (ideal grover, non-black-box) takes into consideration the structure of the oracle, the cost function being the total number of gates in the circuit, each gate having unit cost; the quantum circuit is assumed error-free as well  Both brown and magenta lines are displayed only for comparisons; for both of them, the $y$ axis should be interpreted as number of logical queries (operations, respectively) 	
The curves above the purple line show the overhead introduced by fault tolerance (in terms of required surface code cycles, each surface code cycle assumed to have unit cost)  More optimization at the logical layer will shift the purple line down, whereas more optimization at the fault-tolerant layer will move the upper curves closer to the purple line  Similar remarks to the above hold for the remaining plots in this manuscript }
      	\label{fgr:aes_128_cycles}
	
	For example, the plots in Fig ~\ref{fgr:aes_128_cycles} tells us that if we have $2^{50}$ quantum computers running Grover's algorithm in parallel, with no physical errors, then it would take about $2^{63}$ gate calls (where the purple line intersects the vertical line at $50$), where we assume each gate to have unit cost  Still with no errors, a trivial cost for implementing the cryptographic function (oracle) would bring the cost down to about $2^{38}$ oracle calls per quantum computer  Keeping the actual function implementation, but adding the fault-tolerant layer with a physical error rate of $10^{-7}$ (with appropriate assumptions and using state-of-the-art quantum error correction) pushes the cost up to around $2^{76}$ surface code cycles per quantum computer (where now each code cycle is assumed to have unit cost)  Similar remarks hold for the remaining plots in this manuscript 
        \includegraphics[width=0 429\textwidth]{figures/AES-128_time pdf}
      	\captionof{figure}{AES-128 block cipher  Required time per processor, as a function of the  number of processors ($\log_2$ scale)  The horizontal dotted line indicates one year  The $x$-axis is deliberately extended to show the necessary number of CPUs for a total time of one year  Thus the figure shows that it would take, with the stated assumptions, over $2^{80}$ parallel quantum searches to break AES-128 in a year  Similar remarks to the above hold for the remaining plots in this manuscript }
      	\label{fgr:aes_128_time}
        \includegraphics[width=0 429\textwidth]{figures/AES-128_phys pdf}
	\captionof{figure}{AES-128 block cipher  Physical footprint (physical qubits) per processor, as a function of the number of processors ($\log_2$ scale) }
      	\label{fgr:aes_128_phys}
        \includegraphics[width=0 429\textwidth]{figures/AES-128_phys_total pdf}
	\captionof{figure}{AES-128 block cipher  Total physical footprint (physical qubits), as a function of the number of processors ($\log_2$ scale)  Note that the qubits are not correlated across processors }
      	\label{fgr:aes_128_phys_total}

\subsection{AES-192}

	
        \includegraphics[width=0 429\textwidth]{figures/AES-192_cycles pdf}
      	\captionof{figure}{AES-192 block cipher  Required surface clock cycles per processor, as a function of the  number of processors ($\log_2$ scale) }
      	\label{fgr:aes_192_cycles}
	
        \includegraphics[width=0 429\textwidth]{figures/AES-192_time pdf}
      	\captionof{figure}{AES-192 block cipher  Required time per processor, as a function of the  number of processors ($\log_2$ scale) }
      	\label{fgr:aes_192_time}
	
        \includegraphics[width=0 429\textwidth]{figures/AES-192_phys pdf}
	\captionof{figure}{AES-192 block cipher  Physical footprint (physical qubits) per processor, as a function of the number of processors ($\log_2$ scale) }
      	\label{fgr:aes_192_phys}
	
        \includegraphics[width=0 429\textwidth]{figures/AES-192_phys_total pdf}
	\captionof{figure}{AES-192 block cipher  Total physical footprint (physical qubits), as a function of the number of processors ($\log_2$ scale)  Note that the qubits are not correlated across processors }
      	\label{fgr:aes_192_phys_total}


\subsection{AES-256}

	
        \includegraphics[width=0 429\textwidth]{figures/AES-256_cycles pdf}
      	\captionof{figure}{AES-256 block cipher  Required surface clock cycles per processor, as a function of the  number of processors ($\log_2$ scale) }
      	\label{fgr:aes_256_cycles}
	
        \includegraphics[width=0 429\textwidth]{figures/AES-256_time pdf}
      	\captionof{figure}{AES-256 block cipher  Required time per processor, as a function of the  number of processors ($\log_2$ scale) }
      	\label{fgr:aes_256_time}
	
        \includegraphics[width=0 429\textwidth]{figures/AES-256_phys pdf}
	\captionof{figure}{AES-256 block cipher  Physical footprint (physical qubits) per processor, as a function of the number of processors ($\log_2$ scale) }
      	\label{fgr:aes_256_phys}
	
        \includegraphics[width=0 429\textwidth]{figures/AES-256_phys_total pdf}
	\captionof{figure}{AES-256 block cipher  Total physical footprint (physical qubits), as a function of the number of processors ($\log_2$ scale)  Note that the qubits are not correlated across processors }
      	\label{fgr:aes_256_phys_total}

\section{Hash functions\label{sct::hash}}
In this section we study the effect of parallelized Grover attacks on the SHA-256~\cite{SHA2} snd SHA3-256~\cite{SHA3} family of hash functions  We used the highly optimized logical circuits produced in~\cite{10 1007/978-3-319-69453-5_18} 

\subsection{SHA-256}

        \includegraphics[width=0 429\textwidth]{figures/SHA-256_cycles pdf}
      	\captionof{figure}{SHA-256 cryptographic hash function  Required surface clock cycles per processor, as a function of the  number of processors ($\log_2$ scale) }
      	\label{fgr:sha_256_cycles}
        \includegraphics[width=0 429\textwidth]{figures/SHA-256_time pdf}
      	\captionof{figure}{SHA-256 cryptographic hash function  Required time per processor, as a function of the  number of processors ($\log_2$ scale) }
      	\label{fgr:sha_256_time}
        \includegraphics[width=0 429\textwidth]{figures/SHA-256_phys pdf}
	\captionof{figure}{SHA-256 cryptographic hash function  Physical footprint (physical qubits) per processor, as a function of the number of processors ($\log_2$ scale) }
      	\label{fgr:sha_256_phys}
        \includegraphics[width=0 429\textwidth]{figures/SHA-256_phys_total pdf}
	\captionof{figure}{SHA-256 cryptographic hash function  Total physical footprint (physical qubits), as a function of the number of processors ($\log_2$ scale)  Note that the qubits are not correlated across processors }
      	\label{fgr:sha_256_phys_total}


\subsection{SHA3-256}

        \includegraphics[width=0 429\textwidth]{figures/SHA3-256_cycles pdf}
      	\captionof{figure}{SHA3-256 cryptographic hash function  Required surface clock cycles per processor, as a function of the  number of processors ($\log_2$ scale) }
      	\label{fgr:sha3_256_cycles}
        \includegraphics[width=0 429\textwidth]{figures/SHA3-256_time pdf}
      	\captionof{figure}{SHA3-256 cryptographic hash function  Required time per processor, as a function of the  number of processors ($\log_2$ scale) }
      	\label{fgr:sha3_256_time}
        \includegraphics[width=0 429\textwidth]{figures/SHA3-256_phys pdf}
	\captionof{figure}{SHA3-256 cryptographic hash function  Physical footprint (physical qubits) per processor, as a function of the number of processors ($\log_2$ scale) }
      	\label{fgr:sha3_256_phys}
        \includegraphics[width=0 429\textwidth]{figures/SHA3-256_phys_total pdf}
	\captionof{figure}{SHA3-256 cryptographic hash function  Total physical footprint (physical qubits), as a function of the number of processors ($\log_2$ scale)  Note that the qubits are not correlated across processors }
      	\label{fgr:sha3_256_phys_total}
\section{Bitcoin~\label{sct::bitcoin}}
In this section we analyze the security of Bitcoin's~\cite{satoshi:bitcoin} proof-of-work protocol, which is based on finding a hash\footnote{The hash function being used by the protocol is H($x$) := SHA-256(SHA-256($x$) } pre-image which that starts
with a certain number of zeros  The latter is dynamically adjusted by the protocol so that the problem is on average solved by
the whole network in 10 minutes  Currently, it takes around $2^{75}$ classical hashing operations~\cite{btc_difficulty} for finding a desired hash pre-image successfully via brute-force search with specialized hardware 
        \includegraphics[width=0 429\textwidth]{figures/SHA-256-Bitcoin_cycles pdf}
      	\captionof{figure}{Bitcoin's cryptographic hash function H($x$) := SHA-256(SHA-256($x$))  Required surface clock cycles per processor, as a function of the  number of processors ($\log_2$ scale) }
      	\label{fgr:sha_256_bitcoin_cycles}
        \includegraphics[width=0 429\textwidth]{figures/SHA-256-Bitcoin_time pdf}
      	\captionof{figure}{Bitcoin's cryptographic hash function H($x$) := SHA-256(SHA-256($x$))  Required time per processor, as a function of the  number of processors ($\log_2$ scale) }
      	\label{fgr:sha_256_bitcoin_time}
        \includegraphics[width=0 429\textwidth]{figures/SHA-256-Bitcoin_phys pdf}
	\captionof{figure}{Bitcoin's cryptographic hash function H($x$) := SHA-256(SHA-256($x$))  Physical footprint (physical qubits) per processor, as a function of the number of processors ($\log_2$ scale) }
      	\label{fgr:sha_256_bitcoin_phys}
        \includegraphics[width=0 429\textwidth]{figures/SHA-256-Bitcoin_phys_total pdf}
	\captionof{figure}{Bitcoin's cryptographic hash function H($x$) := SHA-256(SHA-256($x$))  Total physical footprint (physical qubits), as a function of the number of processors ($\log_2$ scale)  Note that the qubits are not correlated across processors }
      	\label{fgr:sha_256_bitcoin_phys_total}


\section{Intrinsic cost of parallelized Grover's algorithm\label{sct::intrinsic_parallel_grover}}

More efficient quantum implementations of AES and SHA imply more efficient cryptanalysis  In this section, we aim to bound how much further optimized implementations of these cryptographic functions could help  We do so by assuming a trivial cost of $1$ for each function evaluation 

\subsection{Searching space of size $2^{56}$}

        \includegraphics[width=0 429\textwidth]{figures/MinimalGrover56bits_cycles pdf}
      	\captionof{figure}{Running Grover's algorithm with a trivial oracle, for a searching space of size $2^{56}$  Required surface clock cycles per processor, as a function of the  number of processors ($\log_2$ scale) }
      	\label{fgr:minimal_grover_56_cycles}
        \includegraphics[width=0 429\textwidth]{figures/MinimalGrover56bits_time pdf}
      	\captionof{figure}{Running Grover's algorithm with a trivial oracle, for a searching space of size $2^{56}$  Required time per processor, as a function of the  number of processors ($\log_2$ scale)  The dotted horizontal line indicates one year  }
      	\label{fgr:minimal_grover_56_time}
        \includegraphics[width=0 429\textwidth]{figures/MinimalGrover56bits_phys pdf}
	\captionof{figure}{Running Grover's algorithm with a trivial oracle, for a searching space of size $2^{56}$  Physical footprint (physical qubits) per processor, as a function of the number of processors ($\log_2$ scale) }
      	\label{fgr:minimal_grover_56_phys}
        \includegraphics[width=0 429\textwidth]{figures/MinimalGrover56bits_phys_total pdf}
	\captionof{figure}{Running Grover's algorithm with a trivial oracle, for a searching space of size $2^{56}$  Total physical footprint (physical qubits), as a function of the number of processors ($\log_2$ scale)  Note that the qubits are not correlated across processors }
      	\label{fgr:minimal_grover_56_phys_total}

\subsection{Searching space of size $2^{64}$}

        \includegraphics[width=0 429\textwidth]{figures/MinimalGrover64bits_cycles pdf}
      	\captionof{figure}{Running Grover's algorithm with a trivial oracle, for a searching space of size $2^{64}$  Required surface clock cycles per processor, as a function of the  number of processors ($\log_2$ scale) }
      	\label{fgr:minimal_grover_64_cycles}
        \includegraphics[width=0 429\textwidth]{figures/MinimalGrover64bits_time pdf}
      	\captionof{figure}{Running Grover's algorithm with a trivial oracle, for a searching space of size $2^{64}$  Required time per processor, as a function of the  number of processors ($\log_2$ scale) }
      	\label{fgr:minimal_grover_64_time}
        \includegraphics[width=0 429\textwidth]{figures/MinimalGrover64bits_phys pdf}
	\captionof{figure}{Running Grover's algorithm with a trivial oracle, for a searching space of size $2^{64}$  Physical footprint (physical qubits) per processor, as a function of the number of processors ($\log_2$ scale) }
      	\label{fgr:minimal_grover_64_phys}
        \includegraphics[width=0 429\textwidth]{figures/MinimalGrover64bits_phys_total pdf}
	\captionof{figure}{Running Grover's algorithm with a trivial oracle, for a searching space of size $2^{64}$  Total physical footprint (physical qubits), as a function of the number of processors ($\log_2$ scale)  Note that the qubits are not correlated across processors }
      	\label{fgr:minimal_grover_64_phys_total}

\subsection{Searching space of size $2^{128}$}

        \includegraphics[width=0 429\textwidth]{figures/MinimalGrover128bits_cycles pdf}
      	\captionof{figure}{Running Grover's algorithm with a trivial oracle, for a searching space of size $2^{128}$  Required surface clock cycles per processor, as a function of the  number of processors ($\log_2$ scale) }
      	\label{fgr:minimal_grover_128_cycles}
        \includegraphics[width=0 429\textwidth]{figures/MinimalGrover128bits_time pdf}
      	\captionof{figure}{Running Grover's algorithm with a trivial oracle, for a searching space of size $2^{128}$  Required time per processor, as a function of the  number of processors ($\log_2$ scale) }
      	\label{fgr:minimal_grover_128_time}
        \includegraphics[width=0 429\textwidth]{figures/MinimalGrover128bits_phys pdf}
	\captionof{figure}{Running Grover's algorithm with a trivial oracle, for a searching space of size $2^{128}$  Physical footprint (physical qubits) per processor, as a function of the number of processors ($\log_2$ scale) }
      	\label{fgr:minimal_grover_128_phys}
        \includegraphics[width=0 429\textwidth]{figures/MinimalGrover128bits_phys_total pdf}
	\captionof{figure}{Running Grover's algorithm with a trivial oracle, for a searching space of size $2^{128}$  Total physical footprint (physical qubits), as a function of the number of processors ($\log_2$ scale)  Note that the qubits are not correlated across processors }
      	\label{fgr:minimal_grover_128_phys_total}


\subsection{Searching space of size $2^{256}$}

        \includegraphics[width=0 429\textwidth]{figures/MinimalGrover256bits_cycles pdf}
      	\captionof{figure}{Running Grover's algorithm with a trivial oracle, for a searching space of size $2^{256}$  Required surface clock cycles per processor, as a function of the  number of processors ($\log_2$ scale) }
      	\label{fgr:minimal_grover_256_cycles}
        \includegraphics[width=0 429\textwidth]{figures/MinimalGrover256bits_time pdf}
      	\caption{Running Grover's algorithm with a trivial oracle, for a searching space of size $2^{256}$  Required time per processor, as a function of the  number of processors ($\log_2$ scale) }
      	\label{fgr:minimal_grover_256_time}
        \includegraphics[width=0 429\textwidth]{figures/MinimalGrover256bits_phys pdf}
	\caption{Running Grover's algorithm with a trivial oracle, for a searching space of size $2^{256}$  Physical footprint (physical qubits) per processor, as a function of the number of processors ($\log_2$ scale) }
      	\label{fgr:minimal_grover_256_phys}
        \includegraphics[width=0 429\textwidth]{figures/MinimalGrover256bits_phys_total pdf}
	\caption{Running Grover's algorithm with a trivial oracle, for a searching space of size $2^{256}$  Total physical footprint (physical qubits), as a function of the number of processors ($\log_2$ scale)  Note that the qubits are not correlated across processors }
      	\label{fgr:minimal_grover_256_phys_total}


\section{RSA schemes\label{sct::rsa}}
In the following section we compute the space/time tradeoffs for attacking public-key cryptographic schemes based on factoring large numbers, 
namely RSA-1024, RSA-2048, RSA-3072, RSA-4096, RSA-7680 and RSA-15360 
For each scheme, we plot the space/time tradeoff points then fit it with a third degree polynomial, for $p_g=10^{-3}$ and $p_g=10^{-5}$, respectively 

\subsection{RSA-1024}

\includegraphics[width=0 475\textwidth]{figures/10minus3/RSA1024 png}
\captionof{figure}{RSA-1024 space/time tradeoffs with physical error rate per gate $p_g=10^{-3}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 3 01\times 10^7$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $3 01\times 10^{11}$, the corresponding number of logical qubits is 2050, and the total number of surface code cycles is $5 86\times 10^{13}$  The quantity $R^2$ represents the coefficient of determination (closer to 1, better the fitting)  The classical security parameter is approximately 80 bits }
\label{fgr:rsa1024a} 

\includegraphics[width=0 475\textwidth]{figures/10minus5/RSA1024 png}
\captionof{figure}{RSA-1024 space/time tradeoffs with physical error rate per gate $p_g=10^{-5}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 2 14\times 10^6$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $3 01\times 10^{11}$, the corresponding number of logical qubits is 2050, and the total number of surface code cycles is $2 93\times 10^{13}$  The classical security parameter is approximately 80 bits }
\label{fgr:rsa1024b}


\subsection{RSA-2048}

\includegraphics[width=0 475\textwidth]{figures/10minus3/RSA2048 png}
\captionof{figure}{RSA-2048 space/time tradeoffs with physical error rate per gate $p_g=10^{-3}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 1 72\times 10^8$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $2 41\times 10^{12}$, the corresponding number of logical qubits is 4098, and the total number of surface code cycles is $4 69\times 10^{14}$  The classical security parameter is approximately 112 bits }
\label{fgr:rsa2048a}



\includegraphics[width=0 475\textwidth]{figures/10minus5/RSA2048 png}
\captionof{figure}{RSA-2048 space/time tradeoffs with physical error rate per gate $p_g=10^{-5}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 9 78\times 10^6$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $2 41\times 10^{12}$, the corresponding number of logical qubits is 4098, and the total number of surface code cycles is $2 35\times 10^{14}$  The classical security parameter is approximately 112 bits }
\label{fgr:rsa2048b}


\subsection{RSA-3072}

\includegraphics[width=0 475\textwidth]{figures/10minus3/RSA3072 png}
\captionof{figure}{RSA-3072 space/time tradeoffs with physical error rate per gate $p_g=10^{-3}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 6 41\times 10^8$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $8 12\times 10^{12}$, the corresponding number of logical qubits is 6146, and the total number of surface code cycles is $1 58\times 10^{15}$  The classical security parameter is approximately 128 bits }
\label{fgr:rsa3072a}

\includegraphics[width=0 475\textwidth]{figures/10minus5/RSA3072 png}
\captionof{figure}{RSA-3072 space/time tradeoffs with physical error rate per gate $p_g=10^{-5}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 2 55\times 10^7$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $8 12\times 10^{12}$, the corresponding number of logical qubits is 6146, and the total number of surface code cycles is $7 91\times 10^{14}$  The classical security parameter is approximately 128 bits }
\label{fgr:rsa3072b}


\subsection{RSA-4096}

\includegraphics[width=0 475\textwidth]{figures/10minus3/RSA4096 png}
\captionof{figure}{RSA-4096 space/time tradeoffs with physical error rate per gate $p_g=10^{-3}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 1 18\times 10^9$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $1 92\times 10^{13}$, the corresponding number of logical qubits is 8194, and the total number of surface code cycles is $3 75\times 10^{15}$  The classical security parameter is approximatively approximately 156 bits }
\label{fgr:rsa4096a}

\includegraphics[width=0 475\textwidth]{figures/10minus5/RSA4096 png}
\captionof{figure}{RSA-4096 space/time tradeoffs with physical error rate per gate $p_g=10^{-5}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 5 70\times 10^7$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $1 92\times 10^{13}$, the corresponding number of logical qubits is 8194, and the total number of surface code cycles is $1 88\times 10^{15}$  The classical security parameter is approximatively approximately 156 bits }
\label{fgr:rsa4096b}


\subsection{RSA-7680}

\includegraphics[width=0 475\textwidth]{figures/10minus3/RSA7680 png}
\captionof{figure}{RSA-7680 space/time tradeoffs with physical error rate per gate $p_g=10^{-3}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 7 70\times 10^{10}$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $1 27\times 10^{14}$, the corresponding number of logical qubits is 15362, and the total number of surface code cycles is $2 64\times 10^{16}$  The classical security parameter is approximately 192 bits }
\label{fgr:rsa7680a}

\includegraphics[width=0 475\textwidth]{figures/10minus5/RSA7680 png}
\captionof{figure}{RSA-7680 space/time tradeoffs with physical error rate per gate $p_g=10^{-5}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 7 41\times 10^{9}$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $1 27\times 10^{14}$, the corresponding number of logical qubits is 15362, and the total number of surface code cycles is $2 47\times 10^{16}$  The classical security parameter is approximately 192 bits }
\label{fgr:rsa7680b}


\subsection{RSA-15360}

\includegraphics[width=0 475\textwidth]{figures/10minus3/RSA15360 png}
\captionof{figure}{RSA-15360 space/time tradeoffs with physical error rate per gate $p_g=10^{-3}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 4 85\times 10^{12}$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $1 01\times 10^{15}$, the corresponding number of logical qubits is 30722, and the total number of surface code cycles is $2 24\times 10^{17}$  The classical security parameter is approximately 256 bits }
\label{fgr:rsa15360a}

\includegraphics[width=0 475\textwidth]{figures/10minus5/RSA15360 png}
\captionof{figure}{RSA-15360 space/time tradeoffs with physical error rate per gate $p_g=10^{-5}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 7 64\times 10^{10}$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $1 01\times 10^{15}$, the corresponding number of logical qubits is 30722, and the total number of surface code cycles is $1 98\times 10^{17}$  The classical security parameter is approximately 256 bits }
\label{fgr:rsa15360b}


\section{Elliptic curve schemes\label{sct::ecc}}
In the following section we compute the space/time tradeoffs for attacking public-key cryptographic schemes based on solving the discrete logarithm 
problem in finite groups generated over elliptic curves, namely NIST P-160, NIST P-192, NIST P-224, NIST P-256, NIST P-384 and NIST P-521  For 
each scheme, we plot the space/time tradeoff points then fit it with a third degree polynomial, for $p_g=10^{-3}$ and $p_g=10^{-5}$, respectively  We 
used the logical circuits from~\cite{1706 06752} 

\subsection{NIST P-160}

\includegraphics[width=0 475\textwidth]{figures/10minus3/P160 png}
\captionof{figure}{NIST P-160 elliptic curve space/time tradeoffs with physical error rate per gate $p_g=10^{-3}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 1 81\times 10^7$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $2 08\times 10^{11}$, the corresponding number of logical qubits is 1466, and the total number of surface code cycles is $4 05\times 10^{13}$  The classical security parameter is 80 bits }
\label{fgr:p160a}

\includegraphics[width=0 475\textwidth]{figures/10minus5/P160 png}
\captionof{figure}{NIST P-160 elliptic curve space/time tradeoffs with physical error rate per gate $p_g=10^{-5}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 1 38\times 10^6$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $2 08\times 10^{11}$, the corresponding number of logical qubits is 1466, and the total number of surface code cycles is $2 03\times 10^{13}$  The classical security parameter is 80 bits }
\label{fgr:p160b}


\subsection{NIST P-192}

\includegraphics[width=0 475\textwidth]{figures/10minus3/P192 png}
\captionof{figure}{NIST P-192 space/time tradeoffs with physical error rate per gate $p_g=10^{-3}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 3 37\times 10^7$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $3 71\times 10^{11}$, the corresponding number of logical qubits is 1754, and the total number of surface code cycles is $7 23\times 10^{13}$  The classical security parameter is 96 bits }
\label{fgr:p192a}

\includegraphics[width=0 475\textwidth]{figures/10minus5/P192 png}
\captionof{figure}{NIST P-192 space/time tradeoffs with physical error rate per gate $p_g=10^{-5}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 2 18\times 10^6$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $3 71\times 10^{11}$, the corresponding number of logical qubits is 1754, and the total number of surface code cycles is $3 62\times 10^{13}$  The classical security parameter is 96 bits }
\label{fgr:p192b}


\subsection{NIST P-224}

\includegraphics[width=0 475\textwidth]{figures/10minus3/P224 png}
\captionof{figure}{NIST P-224 elliptic curve space/time tradeoffs with physical error rate per gate $p_g=10^{-3}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 4 91\times 10^7$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $5 90\times 10^{11}$, the corresponding number of logical qubits is 2042, and the total number of surface code cycles is $1 15\times 10^{14}$  The classical security parameter is 112 bits }
\label{fgr:p224a}

\includegraphics[width=0 475\textwidth]{figures/10minus5/P224 png}
\captionof{figure}{NIST P-224 elliptic curve space/time tradeoffs with physical error rate per gate $p_g=10^{-5}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 3 24\times 10^6$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $5 90\times 10^{11}$, the corresponding number of logical qubits is 2042, and the total number of surface code cycles is $5 75\times 10^{13}$  The classical security parameter is 112 bits }
\label{fgr:p224b}


\subsection{NIST P-256}

\includegraphics[width=0 475\textwidth]{figures/10minus3/P256 png}
\captionof{figure}{NIST P-256 elliptic curve space/time tradeoffs with physical error rate per gate $p_g=10^{-3}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 6 77\times 10^7$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $8 82\times 10^{11}$, the corresponding number of logical qubits is 2330, and the total number of surface code cycles is $1 72\times 10^{14}$  The classical security parameter is 128 bits }
\label{fgr:p256a}

\includegraphics[width=0 475\textwidth]{figures/10minus5/P256 png}
\captionof{figure}{NIST P-256 elliptic curve space/time tradeoffs with physical error rate per gate $p_g=10^{-5}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 4 64\times 10^6$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $8 82\times 10^{11}$, the corresponding number of logical qubits is 2330, and the total number of surface code cycles is $8 60\times 10^{13}$  The classical security parameter is 128 bits }
\label{fgr:p256b}


\subsection{NIST P-384}

\includegraphics[width=0 475\textwidth]{figures/10minus3/P384 png}
\captionof{figure}{NIST P-384 elliptic curve space/time tradeoffs with physical error rate per gate $p_g=10^{-3}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 2 27\times 10^8$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $3 16\times 10^{12}$, the corresponding number of logical qubits is 3484, and the total number of surface code cycles is $6 17\times 10^{14}$  The classical security parameter is 192 bits }
\label{fgr:p384a}

\includegraphics[width=0 475\textwidth]{figures/10minus5/P384 png}
\captionof{figure}{NIST P-384 elliptic curve space/time tradeoffs with physical error rate per gate $p_g=10^{-5}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 1 28\times 10^7$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $3 16\times 10^{12}$, the corresponding number of logical qubits is 3484, and the total number of surface code cycles is $3 08\times 10^{14}$  The classical security parameter is 192 bits }
\label{fgr:p384b}

\subsection{NIST P-521}

\includegraphics[width=0 475\textwidth]{figures/10minus3/P521 png}
\captionof{figure}{NIST P-521 elliptic curve space/time tradeoffs with physical error rate per gate $p_g=10^{-3}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 6 06\times 10^8$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $7 98\times 10^{12}$, the corresponding number of logical qubits is 4719, and the total number of surface code cycles is $1 56\times 10^{15}$  The classical security parameter is 256 bits }
\label{fgr:p521a}

\includegraphics[width=0 475\textwidth]{figures/10minus5/P521 png}
\captionof{figure}{NIST P-521 elliptic curve space/time tradeoffs with physical error rate per gate $p_g=10^{-5}$  The scale is logarithmic (base 2)  Approximately $y(16 3987) \approx 2 30\times 10^7$ physical qubits are required to break the scheme in one day (24 hours)  The number of T gates in the circuit is $7 98\times 10^{12}$, the corresponding number of logical qubits is 4719, and the total number of surface code cycles is $7 78\times 10^{14}$  The classical security parameter is 256 bits }
\label{fgr:p521b}




\section{Summary and conclusions}\label{sct::conclusion}
We analyzed the security of several widely used symmetric ciphers and hash functions against parallelized quantum adversaries  We computed the security parameter, wall-time and physical footprint for each cryptographic primitive  Our attack model was based on a brute force searching via a parallelized version of Grover's algorithm, assuming a surface-code fault-tolerant architecture based on defects and braiding techniques 

It is worth noting that throughout we are assuming that brute-force search where we treat the cryptographic function as a black-box is essentially the optimal attack against SHA and AES, which is currently believed to be the case 

Some symmetric key algorithms are susceptible in a model that permits ``superposition attacks''~\cite{quantph 1602 05973}  In most realistic instances, these attacks are not practical, however they do shed light on the limitations of certain security proof methods in a quantum context, and remind us that we shouldn't take for granted that non-trivial attacks on symmetric key cryptography may be possible 
For example, very recently, there have been several cryptanalysis results~\cite{1712 06239} and~\cite{1802 03856} that attempt to reduce breaking some symmetric algorithms to solving a system of non-linear equations   Solving these non-linear equations is then attacked using a modified version of the quantum linear equation solver algorithm~\cite{PhysRevLett 103 150502}  The results are heavily dependent on the condition number of the non-linear system, which turns to be hard to compute (it is not known for most ciphers and hash functions such as AES or SHA)  Provided the condition number is relatively small, then one may get an  advantage compared to brute-force Grover search  However at this time it is not clear whether this is indeed the case, and we do not have large-scale quantum computers to experiment with 

The quantum security parameter (based on our assumptions of using state-of-the-art algorithms and fault-tolerance methods) for symmetric and hash-based cryptographic schemes is summarized in Table~\ref{tbl1}  For more details about space/time tradeoffs achievable via parallelization of Grover's algorithm please see the corresponding Sec ~\ref{sct::ciphers}, Sec ~\ref{sct::hash} and Sec ~\ref{sct::bitcoin}, respectively 
\begin{table}[h!]
\begin{tabular}{ll}
\hline
Name    & qs  \\
\hline
AES-128 & 106 \\
AES-192 & 139 \\
AES-256 & 172 \\
\hline
SHA-256 & 166 \\
SHA3-256	 &167 \\
Bitcoin's PoW & 75\\
\hline
\end{tabular}
\caption{Quantum security parameter ($qs$) for the AES family of ciphers, SHA family of hash functions, and Bitcoin, assuming a conservative physical error rate per gate $p_g=10^{-4}$ }
\label{tbl1}
\end{table}

We also analyzed the security of asymmetric (public-key) cryptography, in particular RSA and ECC, in the light of new improvements in fault-tolerant 
quantum error correction based on surface code lattice surgery techniques  We computed the space/time tradeoff required to attack 
every scheme, using physical error rates of $10^{-3}$ and $10^{-5}$, respectively  We fitted the data with a third degree polynomial, which resulted in an analytical formula of the number of qubits required to break the 
scheme as a function of time 

The total number of physical qubits required to break the RSA schemes in 24 hours, together with the required number of $T$ gates, corresponding number of surface code cycles and corresponding classical security parameter is summarized in Table~\ref{tbl2}  For more details about possible space/time tradeoffs please see the corresponding Section~\ref{sct::rsa} of the manuscript 
\begin{table}[]
\begin{tabular}{lllll}
\hline
Name      & nq                    & Tc                    & scc           & s        \\
\hline
RSA-1024  & $3 01 \times 10^7$    & $3 01 \times 10^{11}$ & $5 86 \times 10^{13}$ & 80\\
RSA-2048  & $1 72 \times 10^8$    & $2 41 \times 10^{12}$ & $4 69 \times 10^{14}$ & 112\\
RSA-3072  & $6 41 \times 10^8$    & $8 12 \times 10^{12}$ & $1 58 \times 10^{15}$ & 128\\
RSA-4096  & $1 18 \times 10^9$    & $1 92 \times 10^{13}$ & $3 75 \times 10^{15}$ & 156\\
RSA-7680  & $7 70 \times 10^{10}$ & $1 27 \times 10^{14}$ & $2 64 \times 10^{16}$ & 192\\
RSA-15360 & $4 85 \times 10^{12}$ & $1 01 \times 10^{15}$ & $2 24 \times 10^{17}$ & 256\\
\hline
\end{tabular}
\caption{The total physical footprint ($nq$) required to break the RSA schemes in 24 hours, together with the required number of $T$ gates ($Tc$), the corresponding number of surface code cycles ($scc$), and the corresponding classical security parameter ($s$) 
We assume a very conservative physical error rate per gate $p_g=10^{-3}$, more likely to be achievable by the first generations of fault-tolerant quantum computers }
\label{tbl2}
\end{table}

The total number of physical qubits required to break the ECC schemes in 24 hours, together with the required number of $T$ gates, corresponding number of surface code cycles and corresponding classical security parameter is summarized in in Table~\ref{tbl3}  For more details about possible space/time tradeoffs please see the corresponding Section~\ref{sct::ecc} of the manuscript  As observed before in~\cite{1706 06752}, breaking RSA schemes demands more quantum resources in comparison with elliptic curve-based schemes, for the same level of classical security 
\begin{table}[]
\begin{tabular}{lllll}
\hline
Name  & nq                 & Tc                    & scc          & s          \\
\hline
P-160 & $1 81 \times 10^7$ & $2 08 \times 10^{11}$ & $4 05 \times 10^{13}$ & 80\\
P-192 & $3 37 \times 10^7$ & $3 71 \times 10^{11}$ & $7 23 \times 10^{13}$ & 96\\
P-224 & $4 91 \times 10^7$ & $5 90 \times 10^{11}$ & $1 15 \times 10^{14}$ & 112\\
P-256 & $6 77 \times 10^7$ & $8 82 \times 10^{11}$ & $1 72 \times 10^{14}$ & 128\\
P-384 & $2 27 \times 10^8$ & $3 16 \times 10^{12}$ & $6 17 \times 10^{14}$ & 192\\
P-521 & $6 06 \times 10^8$ & $7 92 \times 10^{12}$ & $1 56 \times 10^{15}$ & 260\\
\hline
\end{tabular}
\caption{The total physical footprint ($nq$) required to break the ECC schemes in 24 hours, together with the required number of $T$ gates ($Tc$), the corresponding number of surface code cycles ($scc$), and the corresponding classical security parameter ($s$)  We assume a very conservative physical error rate per gate $p_g=10^{-3}$, more likely to be achievable by the first generations of fault-tolerant quantum computers }
\label{tbl3}
\end{table}

Recent developments in the theory of fault-tolerant quantum error correction have great impact on evaluating the effective strength of cryptographic
schemes against quantum attacks, as the fault-tolerant layer of a quantum computation is the most resource-intensive part of running a quantum  
algorithm  Therefore, monitoring the advances in the theory of quantum error correction is of crucial importance when estimating the strength (or 
weakness) of a cryptographic scheme against a quantum adversary  This work serves as a benchmark against which the impact of future advances can be compared 

\begin{acknowledgments} 
Most of this work is based on research supported by the Global Risk Institute for its members 
We also acknowledge support from NSERC and CIFAR  IQC and the Perimeter Institute are supported in part by the 
Government of Canada and the Province of Ontario   Vlad Gheorghiu thanks Austin Fowler for helpful discussions 
and clarifications regarding lattice surgery methods 
\end{acknowledgments}

\bibliographystyle{aipnum4-1}


Context 2: Bare Acts Live
Himachal Pradesh Town and Country Planning Act, 1977
Himachal Pradesh Town And Country Planning Rules, 1978
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45  Remuneration of Chairman 
46  Leave of absence and appointment etc  of acting Chairman 
47  Meeting of Town and Country Development Authority 
48  Chief Executive Officer 
49  Other officers and servants 
50  Conditions of service of Chief Executive Officer and other officers and servants 
51  Town development schemes 
53  Power to revise the development schemes 
54  Power of State Government to give Directions 
55  Restriction on land use and development 
56  Lapse of scheme 
57  Town development scheme public purpose 
58  Acquisition of land for Town and Country Development Authority 
59  Developments 
60  Disposal of land, buildings and other development works 
61  Development charges 
63  Fund of Town and Country Development Authority 
64  Annual budget 
66  Constitution of special areas 
67  Special area Development Authority 
68  Incorporation of Special Area Development Authority



ground_truth: 172.

prompt_front: Now, answer the following question based on the text below, only give me the answer and do not output any other words.

Question: Who is responsible for carrying out the functions assigned under the act?

Read the following text and answer briefly.

Context 2: 
70  Functions 
71  Powers 
72  Fund of Special Area Development Authority 
73  Annual estimates 
74  Power of State Government of supervision and control 
76  Power of Government to review plans etc  for ensuring conformity 
78  Dissolution of authorities 
79  Right of entry 
80  Jurisdiction of Court 
82  Member and officers to be public servants 
83  Suit and other proceedings 
84  Vacancy not to invalidate proceedings 
85  Member to continue till successor enters upon office 
86  Interpretation of regional plan etc 
87  Powers to moke rules 
89  Power to lay the rules and regulations 
The Himachal Pradesh Town and Country Planning Act, 1977
(as amended by Amendment Act No  22 of 1983)
Amended by Act No  8 of 2009
Act published in the Rajpatra, Extraordinary, dated the 30th September, 1977 vide Law Department Notification No  LLR-D(6)5/77, dated the 22nd September, 1977 
An Act to make provision for planning and development and use of land; to make better provision for the preparation of development plans and sectoral plans with a view to ensuring that town planning schemes are made in a proper manner and their execution is made effective; to constitute the Town and Country and Development Authority for proper implementation of town and country development plan; to provide for the development and administration of special areas through the Special Area Development Authority; to make provision for the compulsory acquisition of land required for the purpose of the development plans and for purposes connected with the matters aforesaid 
Be it enacted by the Himachal Pradesh Legislative Assembly in the Twenty-eighth Year of the Republic of India as follows:-
1  Short title, extent, commencement and application  - (1) This Act may be called the Himachal Pradesh Town and Country Planning Act, 1977 
(3) It shall come into force on such date as the State Government may, by notification, appoint and different dates may be appointed for different areas and for different provisions of this Act 
(4) Nothing in this Act shall apply to-
(a) lands comprised within a cantonment under the Cantonments Act, 1924; (2 of 1924) 
(b) lands owned, hired or requisitioned by the Central Government for the purpose of naval, military and air force works;
(c) lands under the control of railway administration for the purpose of construction and maintenance of works under Chapter III of the Indian Railways Act, 1890; (9 of 1890) and
(d) lands owned by any department of the Central Government where operational constructions are going on 
(a) "agriculture" includes horticulture, farming, raising of annual or periodical crops, fruits, vegetables, flowers, grass, fodder, trees or any kind of cultivation of soil, the reserving of land for fodder, grazing or thatching areas, breeding and keeping of livestock including cattle, horses, donkeys, mules, pigs, breeding of fish and keeping of bees, and the use of land ancillary to the farming of land, but does not include-
(i) keeping of cattle purely for the purpose of milking and selling the milk and milk products,
(ii) a garden which is an appendage of buildings, and the expression "agricultural" shall be construed accordingly;
(b) "amenity" includes roads and streets, water and electric supply, open spaces, parks, recreational area, natural feature, playgrounds, street lighting, drainage, sewerage and other utilities, services and conveniences;
(c) "building" includes any structure or erection, or part of a structure or erection, which is intended to be used for residential, industrial, commercial or other purposes, whether in actual use or not;
(d) "building operation" includes-
(i) erection or re-erection of a building or any part thereof,
(ii) roofing or re-roofing of any part of building or an open space,
(iii) any material alteration or enlargement of a building,
(iv) any such alteration of a building as is likely to alter its drainage or sanitary arrangements, or materially affect its security,
(v) the construction of a door opening on any street or land not belonging to the owner;
(e) "commercial use" means the use of any land or building or part thereof for the purpose of carrying on any trade, business or profession, or sale or exchange of goods of any type whatsoever and includes running of with a view to make profit hospitals, nursing homes, infirmaries, educational institutions, hostels, restaurants and boarding houses not being attached to any educational institutions, sarais and also includes the use of any land or building for storage of goods or as buildings for storage of goods or as an office whether attached to an industry or otherwise;
(f) "court" means the principal civil court of original jurisdiction in the district;
(g) "development" with its grammatical variations means the carrying out of a building, engineering, mining or other operations in, on, over or under land, or the making of any material change in any building or land or in the use of either, and includes sub-division of any land;
(h) "development plan" means interim development plan or development plan prepared under this Act;
(i) "director" means the Director of Town and Country Planning appointed under this Act;
(j) "existing land use map� means a map indicating the use to which lands in any specified area are put at the time of preparing the map, and includes the register prepared, with the map giving details of land-use;
(k) "land" includes benefits to arise out of land and things attached to the earth or permanently fastened to anything attached to the earth;
(l) "member" means a member of a Town and Country Development Authority or a Special Area Development Authority, as the case may be, and includes a Chairman thereof;
(m) "occupier" includes-
(i) a tenant,
(ii) an owner in occupation of or otherwise using his land,
(iii) a rent free tenant,
(iv) a licensee, and
(v) any person liable to pay to the owner, damages for the use and occupation of the land;
(n) "owner" includes a mortgagee in possession, a person who for the time being is receiving or is entitled to receive, or has received, the rent or premium for any land whether on his own account or on behalf of or for the further benefit of any other person or as an agent, trustee, guardian or receiver for any other person or for religious or charitable institutions or who would receive the rent or be entitled to receive the rent or premium if the land were to be let and includes a head of a Government department, General Manager of a Railway and the Chief Executive Officer, by whatever name designated, or a local authority, statutory authority, company, corporation or undertaking in respect of properties under their control;
(o) "planning area" means any area declared to be planning area under this Act;
(p) "region" means any area established to be a region under this Act;
(q) "regional plan" means a plan for the region prepared under this Act and approved by the State Government;
(r) "sector" means any sector of a planning area for which, under the development plan, a detailed sectoral plan is prepared;
(s) "slum area" means any predominantly residential area, where the dwellings which by reason of dilapidation, over-crowding, faulty arrangement of design, lack of ventilation, light or sanitary facilities or any combination of these factors are detrimental to safety, health or moral and which is defined by a development plan as a slum area;
(t) "special area" means a special area designated as such under section 66;
(u) "Special Area Development Authority� means an authority constituted under section 67;
(v) "Town Development Scheme" means a scheme prepared for the implementation of the provisions of a development plan by the Town and Country Development Authority; and
(w) "Town and Country Development Authority" means an authority established under section 40 
Director of Town and Country Planning
3  Director and other officers  - (1) After the commencement of this Act the State Government shall, by notification in the Official Gazette, appoint an officer for the purpose of carrying out functions assigned to him under this Act, as the Director of Town and Country Planning for the State and may appoint such other categories of officers as it may deem fit 
(2) The Director shall exercise such powers and perform such duties as are conferred or imposed upon him by or under this Act and the officers appointed to assist the Director shall, within such area as the State Government may specify, exercise such powers and perform such duties conferred and imposed on the Director by or under this Act as the State Government may, by special or general order, direct 
(3) The officers appointed to assist the Director shall be subordinate to him and shall work under his guidance, supervision and control 
4  Establishment of regions  - (1) The State Government may, by notification,-
(a) declare any area in the State to be a region for the purposes of this Act;
(b) define the limits of such area; and
(c) specify the name by which such region shall be known 
(2) The State Government may, by notification, alter the name of any such region and on such alteration, any reference in any law or instrument or other document to the region shall be deemed to be a reference to the region as re-named unless expressly otherwise provided or the context so requires 
(3) The State Government may, by notification,-
(a) alter the limits of a region so as to include therein or exclude therefrom Such area as may be specified in the notification;
(b) amalgamate two or more regions so as to form one region;
(c) divide any region into two or more region; or
(d) declare that the whole or part of the area comprising a region shall cease to be a region or part thereof 
5  Director to prepare regional plan  - Subject to the provisions of this Act and the rules made thereunder, it shall be the duty of the Director-
(i) to carry out a survey of the regions;
(ii) to prepare an existing land use map; and
(iii) to prepare a regional plan 
6  Survey  - (1) The Director shall, with a view to prepare the existing land use map, and other maps as are necessary for the purpose of regional plan,-
(a) carry out such surveys as may be necessary;
(b) obtain from any department of Government and any local authority such maps, survey reports and land records as may be necessary for the purpose 
(2) It shall be the duty of every Government department and local authority to furnish, as soon as may be possible, maps, reports and record, as may be required by the Director 
7  Contents of regional plan  - The regional plan shall indicate the manner in which land in the region should be used, the phasing of development, the net work of communications and transport, the proposals for conservation and development of natural resources, and in particular-
(a) allocation of land to such purposes as residential, industrial; agricultural or as forests or for mineral exploitation;
(b) reservation of open spaces for recreational purposes, gardens, tree belts, and animal sanctuaries;
(c) access or development of transport and communication facilities such as roads, railways, water ways, and the allocation and development of airports;
(d) requirements and suggestions for development of public utilities such as water supply, drainage and electricity;
(e) allocation of areas to be developed as "Special Areas� wherein new towns, townships, large industrial estates or any other type of large development projects may be established;
(f) landscaping and the preservation of areas in their natural state,
(g) measures relating to the prevention of erosion, including rejuvenation of forest areas;
(h) proposals relating to irrigation, water supply or flood control works 
8  Preparation of regional plan  - (1) After preparation of the existing land use map, the Director shall cause to be prepared a draft regional plan and publish it by making a copy thereof available for inspection and publishing a notice in such form and manner as may be prescribed inviting objections and suggestions from any person with respect to the draft plan before such date as may be specified in the notice, such date not being earlier than sixty days from the publication of the notice  Such notice shall specify in regard to the draft plan the following particulars, namely-
(a) the existing land use map and the narrative report thereon;
(b) a narrative report supported by necessary map and charts explaining the provisions of the draft plan;
(c) a note indicating the priorities assigned to works included in the draft plan and the phasing of the programme of development as such;
(d) a notice on the role being assigned to different departments of Government, the Town and Country Development Authorities; the Special Area Development Authorities, and the Local Authorities in the enforcement and implementation of draft plan 
(2) The Director shall consider all the objections and suggestions received by him within the period specified in the notice under sub-section (1) and shall, after giving a reasonable opportunity to all persons affected thereby of being heard, prepare the regional plan containing such modifications, if any, as he considers necessary and submit it to the State Government for approval together with all connected documents, plans, maps and charts 
9  Finalisation of regional plan  - (1) The State Government may approve the draft regional plan submitted under section 8 with or without modification or reject or return the same to the Director for reconsideration 
(2) Immediately after the draft regional plan is approved under sub-section (1) the State Government shall publish in such manner, as may be prescribed, a notice stating that the regional plan has been approved and mentioning a place where a copy of the plan may be inspected at all reasonable hours and shall specify therein a date on which the regional plan shall come into operation:
Provided that where the State Government approves the draft regional plan with modifications, it shall not be published, unless the State Government having published such modifications in the Official Gazette along with a notice inviting objections and suggestions thereon, within a period of not less than thirty days from the date of publication of such notice have considered the objections and suggestions after giving a reasonable opportunity of being heard to persons affected thereby 
10  Restriction on use of land or development thereof  - (1) Notwithstanding anything contained in any other law for the time being in force, on or after the date of publication of the draft regional plan, no person, authority, department of Government or any other person shall change the use of land for any purpose other than agriculture, or carry out any development in respect of any land contrary to the provisions of the draft plan, without the prior approval of the Director or any officer next to him authorised by the Director, in this behalf 
(2) Notwithstanding anything contained in any law for the time being in force, the permission referred to in sub-section (1) shall not be granted otherwise than in conformity with the provision of the draft or final plan and no permission, if granted, shall be construed to confer any legal right whatsoever on the person seeking the permission 
(3) If any work is carried out in contravention of the provisions of this section, the Municipal Corporation or Municipal Committee within its local area, and the Collector in area outside such local areas, may cause such work to be removed or demolished at the cost of the defaulter, which shall be recovered from him in the same manner as an arrear of land revenue:
Provided that no action shall be taken under this sub-section unless the person concerned is given a reasonable opportunity of being heard and a notice calling upon him to remove or demolish the work within a time specified therein 
(4) Any person aggrieved by the order of the Municipal Corporation, Municipal Committee or Collector, as the case may be, calling upon to remove or demolish the work may prefer an appeal to the Director within fifteen days of the receipt of the notice under sub-section (3) and the order of the Director in such appeal shall be final 
11  Exclusion from claims of amount in certain cases  - Where the regional plan assigns a particular land use to a certain areas and any land situate therein is already put to such use, subject to substantially similar restrictions in force under any other law which was in force on the date on which restrictions were imposed by or under this Act and if amount in respect of such restrictions have already been paid under any such other law which was in force for the time being in respect of the property or any right or interest therein to the claimant, or any predecessor in interest of the claimant, the owner shall not be entitled to any further amount on account of injury or damage caused to his rights by reasons of the restrictions placed on the use of the land under the provisions of this Act 
12  Review of regional plan  - (1) The Director may, on his own motion or if so required by the State Government, at any time after a regional plan has come into operation, undertake the review and evaluation of the regional plan and make such modification in it as may be justified by the circumstances 
(2) The foregoing provisions of this Chapter shall, so far as they can be made applicable, apply to the modifications under sub-section (1) as these provisions apply in relation to the preparation, publication and approval of a regional plan 
Planning Area and Development Plans
13  Planning area  - (1) The State Government may, by notification, constitute planning areas for the purposes of this Act and define the limits thereof 
(2) The State Government may, by notification -
(a) alter the limits of a planning area so as to include therein or excluse therefrom such area as may be specified in the notification;
(b) amalgamate two or more planning areas so as to constitute one planning area;
(c) divide any planning area into two or more planning areas;
(d) declare that the whole or part of the area constituting the planning area shall cease to be a planning area or part thereof 
14  Director to prepare development plans  - Subject to the provisions of this Act and the rules made thereunder, the Director shall-
(a) prepare an existing land use map;
(b) prepare an interim development plan;
(c) prepare a development plan;
(d) prepare a sectoral plan;
(e) carry such surveys and inspections and obtain such pertinent reports from government departments, local authorities and public institutions as may be necessary for the preparation of the plans;
(f) perform such duties and functions as are supplemental, incidental, and consequential to any of the foregoing functions or as may be assigned by the State Government for the purpose of carrying out the provisions of this Act 
15  Existing land use maps  - (1 )The Director shall carryout the survey and prepare an existing land use map and, forthwith publish the same in such manner as may be prescribed together with public notice of the preparation of the map and of the place or places where the copies may be inspected, inviting objections and suggestions in writing from any person with respect thereto within thirty days from the date of publication of such notice 
(2) After the expiry of the period specified in the notice published under sub-section (1), the Director may, after allowing a reasonable opportunity of being heard to all such persons who have filed the objections or suggestions, make such modifications therein as may be considered desirable 
(3) As soon as may be after the map is adopted with or without modifications the Director shall publish a public notice of the adoption of the map and the place or places where the copies of the same may be inspected 
(4) A copy of the notice shall also be published in the Official Gazette and it shall be conclusive evidence of the fact that the map has been duly prepared and adopted 
16  Freezing of land use  - On the publication of the existing land use map under section 15-
(a) no person shall institute or change the use of any land or carry out any development of land for any purpose other than that indicated in the existing land use map without the permission in writing of the Director;
Provided that the Director shall not refuse permission if the change is for the purpose of agriculture;
(b) no local authority or any officer or other authority shall, not withstanding anything contained in any other law for the time being in force, grant permission for the change in use of land otherwise than as indicated in the existing land use map without the permission in writing of the Director;
[(c) no Registrar or the Sub-Registrar, appointed under the Indian Registration Act, 1908, shall, in any planning area constituted under section 13, register any deed or document of transfer of any sub-division of land by way of sale, gift, exchange, lease or mortgage with possession, unless the sub-division of land is duly approved by the Director, subject to such rules as may be framed in this behalf by the State Government:]
Provided that the Registrar or the Sub-Registrar may register any transfer,-
(i) where the land is owned by a person and the transfer is made without involving any further divisions;
(ii) where the partition/sub-division of land is made in a Joint Hindu Family;
(iii) where the lease is made in relation to a part or whole of a building;
(iv) where the mortgage is made for procuring the loans for construction or improvements over the land either from the Government or from any other financial institution constituted or established under any law for the time being in force or recognised by the State Government 
17  Interim development plans  - As soon as may be, after the declaration of a planning area, the Director shall, within such time as may be necessary, prepare, after consultation with local authorities concerned, if any, and submit to the State Government an interim development plan for the planning area or any of its parts and such other area or areas contiguous or adjacent to the planning areas as the State Government may direct to be included in the interim development plan 
(2) The interim development plan shall-
(a) indicate broadly the land use proposed in the planning area;
(b) allocate broadly areas or sector of land for-
(i) residential, industrial, commercial or agricultural purposes,
(ii) open spaces, parks and gardens, green belts, zoological gardens and play-grounds,
(iii) public institutions and offices,
(iv) such special purposes as the Director may deem fit;
(c) lay down the pattern of National and State Highways connecting the planning area with the rest of the region, ring roads, arterial roads and the major roads within the planning areas;
(d) provide for the location of airports, railway stations, bus termini and indicate the proposed extension and development of railways and canals;
(e) make proposals for general land scaping and preservation of natural areas;
(f) project the requirement of the planning area of such amenities and utilities as water, drainage, electricity and suggest their fulfilment;
(g) propose broad based regulations for sectoral development, by way of guide-lines, within each sector of the location, height, size of buildings and structures, open spaces, court-yards and the use to which such buildings and structures and land may be put;
(h) lay down the board-based traffic circulation patterns in a city;
(i) suggest architectural control features, elevation and frontage of buildings and structures;
(j) indicate measures for flood control, prevention of air and water pollution, disposal of garbage and general environmental control 
(3) Subject to provisions of the rules made under this Act for regulating the form and contents of the interim development plan any such plan shall include such maps and such descriptive matter as may be necessary to explain and illustrate the proposals in the interim development plan 
(4) As soon as may be, after the submission of the interim development plan, under sub-section (1) the State Government may either approve the interim development plan or may approve it with such modification as it may consider necessary 
(5) The State Government shall publish the interim development plan as approved under sub-section (4) in the Official Gazette  The interim development plan shall come into operation from the date of its publication in the Official Gazette and shall be binding on all local authorities functioning within the planning areas 
18  Development plan  - A development plan shall -
(a) indicate broadly the land use proposed in the planning areas;
(b) allocate broadly areas or sector of land for,-
(c) lay down the pattern of National and State Highways connecting the planning area with the rest of the region, ring roads, arterial roads, and the major roads within the planning area;
(d) provide for the location of airports, railway stations, bus termini and indicate the proposed extension and development of railways;
(g) propose broad-based regulations for sectoral development, by way of guide-line, within each sector of the location, height, size of buildings and structures, open spaces, court-yards and the use to which such buildings and structures and land may be put;
(h) lay down the broad-based traffic circulation patterns in a city;
19  Publication of draft development plan  - (1) The Director shall forthwith publish the draft development plan prepared under section 18 in such manner as may be prescribed together with a notice of the preparation of the draft development plan and the place or places where the copies may be inspected, inviting objections and suggestions in writing from any person with respect thereto, within thirty days from the date of publication of such notice Such notice shall specify in regard to the draff development plan the following particulars, namely:-
(i) the existing land use maps;
(ii) a narrative report, supported by maps and charts, explaining the provisions of the draft development plan;
(iii) the phasing of implementation of the draft development plan as suggested by the Director,
(iv) the provisions for enforcing the draft development plan and stating the manner in which permission to development may be obtained;
(v) an approximate estimate of the cost of land acquisition for public purposes and the cost of works involved in the implementation of the plan 
(2) The Director shall, not later than ninety days after the date of expiry of the notice period under sub-section (1), consider all the objections and suggestions as may be received within the period specified in the notice under sub-section (1)and shall, after giving reasonable opportunity to all persons affected thereby of being heard, make such modifications in the draft development plans as he may consider necessary, and submit, not later than six months after the publication of the draft development plan, the plan so modified, to the State Government for approval together with all connected documents, plans, maps and charts 
20  Sanction of development plans  - (1) As soon as may be after the submission of the development plan under section 19 the State Government may either approve the development plan or may approve it with such modifications as it may consider necessary or may return it to the Director to modify the same or to prepare a fresh plan in accordance with such directions as it may issue in this behalf 
(2) Where the State Government approves the development plan with modifications, the State Government shall, by a notice, published in the Official Gazette, invite objections and suggestions in respect of such modifications within a period of not less than thirty days from the date of publication of the notice in the Official Gazette 
(3) After considering objections and suggestions and after giving a hearing to the persons desirous of being heard the State Government may confirm the modification in the development plan 
(4) The State Government shall publish the development plan as approved, under the foregoing provisions in the Official Gazette and shall along with the plan publish a public notice, in such manner as may be prescribed, of the approval of the development plan and the place or places where the copies of the approved development plan may be inspected 
(5) The development plan shall come into operation from the date of publication thereof in the Official Gazette and as from such date shall be binding on all Development Authorities constituted under this Act and all local authorities functioning within the planning area 
(6) After the coming into operation of the development plan, the interim development plan shall stand modified or altered to the extent the proposals in the development plan are at variance with the interim development plan 
Sectoral Plan
21  Director to prepare sectoral plan  - The Director may, on his own motion, at any time after the publication of the development plan, or thereafter if so required by the State Government shall, within six months of such requisition, prepare a sectoral plan 
22  Contents of sectoral plan  - (1) The sectoral plan shall enlarge the details of land use as indicated in the development plan and shall -
(a) indicate the land liable to acquisition for public purpose or the purposes of the Union Government, the State Government, the Town and Country Development Authority, the Special Area Development Authority, the local authority or any other authority established by or under any enactment for the time being in force 
Provided that no land shall be so designated unless the acquisition proceedings are likely to be completed within ten years of the preparation of the plan;
(b) define in detail and provide for areas reserved for agriculture, public and semi-public open spaces, parks, playgrounds, gardens, recreational areas, green belts and natural reserves;
(c) allocate in detail areas or sectors for residential, commercial, industrial, agricultural and other purposes;
(d) define and provide for the complete road and street pattern for the present and in the future and indicate the traffic circulation;
(e) lay down in detail the projected road and street improvement;
(f) indicate and provide for areas reserved for public buildings, institutions and civic developments;
(g) assess, make projections for and provide for the future requirements of amenities, services and utilities such as municipal, transport, electricity, water and drainage;
(h) prescribe in detail the sectoral regulations for each sector, with a view to facilitating on individual layout and regulating the location, height, number of storeys and the size of buildings and other structures, the size of the court-yards, courts and other open spaces and the use of the buildings, structures and land;
(i) define areas which have been badly laid out or areas which have developed so as to form slums, and provide for their proper development and/or relocation;
(j) designate areas for future development and expansion;
(k) indicate the phasing of the programme of development 
(2) The sectoral plan may and if possible shall, indicate -
(a) control over architectural features; elevation and frontage of buildings and structures; and
(b) the details of development of specific areas for housing, shopping centres, industrial areas, educational and cultural institutions and civic centres 
23  Provisions of sections 19 and 20 to apply to sectoral plan  - The provisions of sections 19 and 20 shall apply for the preparation, publication, approval and operation of sectoral plan as they apply in respect of the development plan 
24  Review of development plan and sectoral plan  - The Director may on his own motion or if so required by the State Government shall, at any time after the sectoral plan has come into operation, undertake a review and evaluation of the development plan and sectoral plan 
(2) The foregoing provisions of sections 19, 20 and 23 shall, so far as may be apply to the modification under sub-section (1) as those provisions apply in relation to the preparation, publication and approval of a development plan or a sectoral plan 
Control of Development And Use of Land
25  Director to control land use  - The overall control of development and the use of land in the planning area shall, as from the date of publication in the Official Gazette of a notification by the State Government, vest in the Director 
26  Conformity with development plan  - (1) After coming into force of the development plan, the use and development of land shall conform to the provisions of the development plan:
Provided that the Director may, at his discretion, permit the continued use of land for the purpose for which it was being used at the time of the coming into Operation of the development plan 
Provided further that such permission shall not be granted for a period exceeding seven years from the date of coming into operation of the development plan 
27  Prohibition of development without permission  - After coming into operation of the development plan, no person shall change the use of any land or carry out any development of land without the permission in writing of the Director 
Provided that no such permission shall be necessary -
(a) for carrying out works for the maintenance, repair or alteration of any building which does not materially alter the external appearance of the building;
(b) for carrying out work for the improvement or maintenance of a highway, road or public street by the Union or State Government or an authority established under this Act or by a local authority having jurisdiction, provided that such maintenance or improvement does not change the road alignment contrary to the provisions of the development plan;
(c) for the purpose of inspecting, repairing or renewing any drain, sewers, mains, pipes, cables, telephone or other apparatus including the breaking open of any street or other land for that purpose;
(d) for the excavation or soil shaping in the interest of agriculture;
(e) for restoration of land to its normal use where land has been used temporarily for any other purposes 
(f) for use for any purpose incidental to the use of building for human habitation, or any other building or land attached to such buildings;
(g) for the construction of a road intended to give access to land solely for agricultural purposes
28  Development undertaken on behalf of Union or State Government  - (1) When the Union Government or the State Government intends to carry out development of any land for the purpose of its departments or offices or authorities, the officer-in-charge thereof shall inform in writing to the Director the intention of the Government to do so, giving full particulars thereof, accompanied by such documents and plans as may be prescribed at least thirty days before undertaking such development 
(2) Where the Director raises any objection to the proposed development on the ground that the development is not in conformity with the provisions of the development plan, the officer shall,-
(i) make necessary modification in the proposals for development to meet the objections raised by the Director, or
(ii) submit the proposal for development together with the objections raised by the Director to the State Government for decision:
Provided that where no modification is proposed by the Director within thirty days of the receipt of the proposed plan by the Government, the plan will be presumed to have been approved 
(3) The State Government, on receipt of the proposals for development together with the objections of the Director shall, approve the proposals with or without modifications or direct the officer to make such modifications in the proposals as it considers necessary in the circumstances 
(4) The decision of the State Government under sub-section (3) shall be final and binding 
29  Development by local authority or by any authority constituted under this Act  - Where a local authority or any authority specially constituted under this Act intends to carry out development on any land for the purpose of that authority, the procedure applicable to the Union or State Government, under section 28 shall, mutatis' mutandis, apply in respect of such authority 
30  Application for permission for development by others  - (1) Any person, not being the Union Government, State Government, a local authority or a special authority constituted under this Act intending to carry out any development on any land, shall make an application in writing to the Director for permission, in such form and containing such particulars and accompanied by such documents as may be prescribed 
(2) Such application shall also be accompanied by such fee as may be prescribed 
[30A  Exemption from development permission in rural areas falling within Planning or Special Area  - (1) Any person who owns land in rural areas, falling within Planning or Special Areas wherein neither Interim Development Plan nor Development Plan has been notified, shall be exempted from permission under this Act for the following development activities up to the limits as may be prescribed: -
(i) Residential activities such as farm-houses and residential houses up to three storeys, cattle shed, toilet, septic tank, kitchen, store, parking shed or garage and rain shelter;
(ii) Commercial activities such as basic commercial activities like shops of general merchandise, cobbler, barber, tailoring, fruit, vegetable, tea or sweet, eating places and dhabas, chemist and farm produce sale depot;
(iii) Service Industries such as cottage or house-hold, service industries like carpentry, knitting, weaving, blacksmith, goldsmith, atta-chakki with capacity up to five horse-power, water mill, agriculture equipments or machinery repair, electrical, electronic and house-hold appliances;
(iv) Public amenities such as public amenities like panchayat offices, schools, mahila mandals, yuvak mandals, community halls, post offices, dispensaries and clinics (including health, veterinary and Indian System of Medicines) information technology kiosks, patwar khanas, guard huts, anganwaries, electricity and telephone installations and connections, roads and paths, ropeways, water tanks, rain harvesting tanks, overhead or underground water tan 



ground_truth: The Director of Town and Country Planning is responsible for carrying out the functions assigned under the act.

prompt_front: Now, answer the following question based on the text below, only give me the answer and do not output any other words.

Question: Why is it important for the sides of the fuselage to be sloped (tumbled home)?

Read the following text and answer briefly.

Context 3: Probably one of the most frustrating things about building experimental aircraft, especially when starting with a minimum of pre-fabricated parts, is to start building and ending up with an unexpected result  Every builder starts a new project by wanting it to go "perfectly " So when things aren't going well, especially at the beginning, the frustration can lead to an unfinished airplane 
This is the first article in a series dedicated to helping builders of the Rand Robinson KR series planes build a straight and true fuselage -- the first part of the construction process  Borrowing from modern boatbuliding techniques, focus will be on the KR-2S, but the principles apply to the entire lineup of KR-1 & KR-2 series planes 
While building the KR-2(s) a common surprise is encountered by builders when the completed fuselage sides are laid into position to form the fuselage box section  With many hours spent building the sides flat, finding the once straight longerons that now bow up from the building surface, form a most dissatisfying "banana" shape  Especially when using the preformed fiberglass parts, this curve in the top longeron is not acceptable  The builder is left wondering what went wrong and no amount of clamping or brute force forming will solve the problem to any degree of satisfaction  The problem is not the builder's fault  The solution starts by understanding the three dimensional relationship of the assembled parts being built 
First understand that the plans show the finished form of the plane  They show the "projected" form as you would expect to see it if viewing an actual plane from the top, ends and from the side  Since the sides are sloped (flared) outward, looking from the side, the distances given by measuring the profile drawing are "foreshortened" and don't give the proper shape for building the fuselage with a flat top longeron  What needs to be done is to "develop" the "true" distances and shape of the flat panel so that when it is curved into position, the longerons lay flat 
Second, understand that the dimensions called for in the plans put a twist in the sides that tends to work the panel in two directions of curvature  This twist makes the panel "undevelopable" meaning that that shape cannot be unrolled into an equivalent flat shape  This is important when laying out the side and bottom panels onto flat plywood  To illustrate this, try forming a piece of paper around a soda can  The paper can be formed flat around the can either straight or at a diagonal to it's length  It has only one direction of curvature and is by definition "developable"  Now try to form the same piece of paper around a baseball  It won't lie flat on the surface without some deformation (folding, wrinkling or tearing) of the paper  The ball has curvature in more that one direction and is a "compounded" shape  Paper (or plywood) can only be readily formed in developable shapes as opposed to aluminum or other metal which can accept in plane deformation  A developable surface is needed to lay out a curved surface when the materials used can't be deformed with any degree of in-plane strain 
Initially, the fuselage sides are laid out flat with reference to the top longeron measured to a straight chalk line  The bowing problem starts when the side panels are bent and sloped to form the fuselage box section  If the sides were not sloped (tumbled home), the section formed would be cylindrical and the longerons would lie flat  Since the sides are tumbled home, the section formed is now conical  When a conical shape is cut with a plane (building surface) not perpendicular to it's axis, the shape formed is elliptical -- exactly what happens with the top longeron  When it's built flat, bent to form a cylindrical section, and sloped to form a conical section, it takes on an elliptical shape firewall to tailstock 
This method borrows heavily from proven techniques used in the marine trades  It should be stressed at this point that although the layout procedure is not complicated, it is important to take your time  If the layout is not going well initially, start over! Better to erase layout errors now than to have them built it and cause surprises later 
Layout to ensure a fair and true fuselage starts by drawing a reference line (baseline) on the building surface  Refer to figures 2 & 3 and use a wire guide to draw a very straight baseline  About 500 lbs  Of tension should be adequate  One could use a chalk line, but we're talking airplanes here, not house framing 
The main layout difference is that the baseline isn't used as a reference for the top longeron  The baseline references the mid point of the firewall for the developed (and true dimensioned) side panel  Although the baseline will still be the reference, the top and bottom longerons will be laid separately 
Layout differences don't end there  Each of the stations (vertical members) will be laid out with a calculated separation so that when the panels are formed into position, they land on the spacing called for in the plans  Another major difference is that the bottom & side panels are applied after forming the fuselage box section  This is mainly to obtain the ability to "fair" the side and bottom surfaces and insure a straight and true shape 
Refer to figure 1 for the layout of the new developed side panel  The firewall (station a) is layed out perpendicular to the baseline  Longitudinal (station) measurements are given along the length of the baseline from the firewall  Vertical dimensions are given to reference the angle and breadths of the station at the baseline 
Notice that the top longeron is bowed outward and that the stations are spaced slightly greater than called out in the plans  When the panels are formed into the box frame section ,they will work into the dimensions specified in the plans 
Strike a centerline, longer than is needed on the building surface using a wire guide  Draw off the firewall line perpendicular to the centerline at one end 
Using the distances listed in the balloons, mark them off on the centerline  Distances are measured to the nearest sixteenth of an inch  Take time to mark them off carefully  Don't mark off the distances in a cumulative fashion  Use the firewall as a common reference 
Using the angles listed at each station, mark off a station line longer than is needed  The angles are measured to the nearest hundredth of a degree  Take time to mark them off carefully 
At each station, start by marking off each short (bottom longeron) line distance from the centerline  Use your set of trammels or beam compass for doing this  Mark the intersection of the short line with the station line 
At each station, mark off each long (top longeron) line distance from the intersection of the short line distance and the station line  Again the trammels or beam compass is best for completing this step  Mark the intersection of the long line distance with the station line 
Using the longeron as a batten, trace out the inside and outside curves of the longeron  After the batten is secure, in between each station, fasten a keeper block inside and outside to preserve the shape of the longeron taking care to avoid potential future interference with the diagonal members to be installed later  The fairing blocks can be removed or left in place if they won't interfere with building  The vertical station members and their diagonals can now be measured and positioned  Remember to refer to the plans for the material thickness direction 
After vertical and diagonal members are cut and fitted, take time to draw their outlines on the building surface to cut down on time and confusion when laying out the opposite side 
Finishing the side panel is accomplished in a manner similar to that called for in the handbook with the exception that the side and bottom skin panels will be attached later 
The next article in the series will discuss jigging and building techniques to ensure alignment and straightness of the flat built side panels  Also covered will be building a "strongback" jig to assure alignment of the side panels when they are formed into their final shape 
Part 3 in the series will cover assembly of the side panels using the jigs  Some joint details will be discussed that will ensure a stronger and more fair fuselage assembly  Also covered will be the layout & attachment of the side and bottom ply skins 
U S  Mail: Densmore Associates, inc 
ANSI "D" size, computer generated plots of all the layout drawings in this series are available from the author for $30 plus postage & handling  Full (true size) scale plots may be made available depending on demand 
"Scarfing" is the practice of splicing plywood so that short pieces of plywood can be used to span long distances  On the KR, it is required on both the fuselage skins and spar webs  The angle of the splice should be 10 to 12 degrees to maintain strength across the joint  Also, joints should coincide with structural members, such as spar webs or fuselage truss members 
This scarfer is made by mating a regular plunge router (this one costs about $50) to a table saw  Obviously, you really only need a table saw to cut the chamfer, but it does make a nice heavy table for scarfing  You could just as easily use a large work table as the base First, set the table saw for a 5 5 degree cut (for a 1:12 joint, or 6 5 degree cut for a 10:1 joint), and run a 1 x 6 through on edge to chamfer a corner on the board  Then drill the board for three router mounting holes (two are countersunk) and connect the assembly to the table saw with two 1/4 inch bolts  Use a long (2-3 inch) straight cutting bit to do the cutting  Adjust the bit so it doesn't interfere with your table top, and go to town  Keep pressure on the plywood to ensure contact with the table while you're scarfing  Make sure you feed your material from the same end as you would if you were sawing, or the router will take your plywood away from you and put a big dent in your garage door 
In the late 60's Ken Rand and Stuart Robinson were working as flight system engineers for Douglas Avionics  Ken was working as an electrical engineer, having previously worked for Sperry as an autopilots project engineer, while Stu's degree was in aeronautical engineering from Northrop University  They were two of the guys at the end of the DC-8,9, and 10 assembly lines responsible for correcting some of the nits and picks in various systems before delivery to the customer 
They both wanted to build a fast, inexpensive airplane which was also economical to maintain  Several designs were considered, and plans were bought first for the Jeanie's Teenie and then the Taylor Monoplane  The Monoplane was more to their liking, but would require some modification to fit their needs  A cooperative redesign effort ensued, with virtually no dimensions left untouched  Only the basic fuselage structure, airfoil, and powerplant were retained  The tail shape was Stu's, and came directly from the big DC-8s parked on the ramp outside his office window  The landing gear was designed by Ken, after seeing the gear on a Dewey Bird at Santa Paula airport 
Ken was killed in his KR2 a short time later while flying over Cajon Pass in what was apparently a bad weather / low fuel accident  Ken's wife Jeanette became owner of RR overnight, and stepped up to keep the plans and parts coming  Much of the engineering needs are handled by Bill Marcy of Denver, who's been helping out since early '79 
To date, almost 6000 KR1, 9200 KR2, and 760 KR2S plan sets have been sold  1200 KR2s are estimated to be flying, with 5 KR2Ss now in the air  Much of the development work done on KR's is now done by the builders themselves  KR builders tend to be innovative, which leads to some interesting modifications  Some of the mods that work eventually creep into the plans  The KR2S is a case in point  Many builders who'd heard of the pitch sensitivity and tight cabin of the KR2 began to build an enlarged version, with the length determined by the most commonly available longeron material  The result is a KR2 that is stretched 2" between firewall and main spar, and 14" behind the main spar  Higher gross weights dictated more wing area, with the new standard becoming the Diehl wing skin  Those who plan to carry passengers commonly stretch the cabin width a few inches, although 1 5 inches is the limit if you still want to use RR's premolded parts 
Mike Stearns addresses the KR Forum crowd 
This year's KR Forum featured guest speakers Mike Stearns, Steve Trentman, and Bill Marcey  Mike Stearns spoke on several topics, including the many sources for KR and homebuilding information available on the Internet  He also mentioned KRNet, the list server devoted entirely to KR aircraft, as well as several notable World Wide Web home pages  He also brought a sample of the new Rand Robinson wing skins with him, and discussed their high temperature core prepreg construction  His KR2S will receive the first set, which is currently being installed at Hinson Composites 
Steve Trentman spoke on his turbine installation  It uses a turbine engine which saw duty as an A7 attack jet starter engine  Total weight is about 85 pounds, while putting out around 90 horsepower  There is a small stockpile of these engines available from government surplus  sources  This engine can only be throttled back to 52% power, which leads to some pretty interesting landings  One inflight failure has been logged so far, with very little damage to the aircraft  More on this exciting development in next month's issue of KROnline 
Les Palmer's KR2 N202LP won Best KR2, Best Engine Installation, and People's Choice awards at the 1995 KR Gathering at Columbia, TN  After researching the KR series, and reading Neil Bingham's "A Critical Analysis of the KR2" (Jan 88 Sport Aviation), Les decided to build his as a single seater, stretched 24" in the tail, while maintaining a stock width firewall  His fuselage is made from Douglas fir, which weighs in at 4 lbs heavier than if constructed from spruce  It is skinned with 1/8" birch plywood  Spars are covered with plywoood on both fore and aft sides, ala KR2S  Diehl wing skins provide the lift  Horizontal stabilizer and elevator were stretched 7" longer on each side, while the vertical stabilizer and rudder were stretched 8" taller    The fuselage to cowling junction was made more graceful by adding 1 5 inches to the height of the firewall end of the fuselage sides 
Les's canopy is a Dragonfly, using a four linkage system to swing forward when opening  The canopy frame fits snugly into a recess in the foward deck, providing an excellent wind and water seal  The fiberglass work is exemplary 
Seating is luxurious for one 
The cowling is also a work of art, and uses NACA ducts for efficiency  Female molds were made for all the fiberglass parts on Les's plane, so he could proabably be persuaded to make more, if demand dictates  Les also machines a multitude of KR aluminum and steel parts which he now offers for sale 
The firewall was reinforced with aluminum brackets and angles bolted between the longerons in anticipation of the 200 lb Subaru EA-81 engine installation  His 100 HP Asian version is outfitted with an American Holley 5200 caburetor and manifold  It uses a PSRU of Les's own design, featuring two spur gears with a 1 69:1 reduction ratio and a toothed belt  Other than tapping the crank for larger bolts to mount the redrive, no other engine modifications were required  Also, this is probably the only air conditioned KR2 on the planet  The prop is a 60/63 Hegy 
Originally built as a taildragger, the fixed gear is made from 4130 steel tubing  Custom cast 6 00x6 aluminum wheels and steel rotors are mated with 6" Cleveland calipers for braking  An early taxi test accident damaged the main gear, and prompted Les to change to tricycle gear  Again, he designed his own fiberglass main gear, and uses a Diehl nose wheel fork with a 4130 strut and 6" wheel up front 
Early tests revealed cooling problems, which prompted a radiator move from the firewall to a lower cowling location 
The first flight was almost a disaster, as test pilot Randy Smith lost power right after takeoff  He managed a 180 with a safe downwind landing with only minor nosewheel pant damage  The culprit proved to be a spark plug with too much reach, which was quickly remedied  Subsequent flights have shown water temp to be about 210 degrees, oil temp is 220-230, and airspeed is about 180 mph 
Shopping for the Partially Built KR 
This story starts about twenty years ago when I first started looking at the KR-2 as the plane I'd like to build  The only problem at that time was a lack of money, lack of knowledge, and a lack of job stability  I liked the design, except for the low ground clearance of the retractable gear and that a KR was going to be a tight fit for me to fly 
Over the past twenty years I've owned a number of planes, but still always wanted to build my own  I needed one that would fit me, my budget requirements, and have the speed and performance that I wanted  When "KITPLANES" published the article featuring Roy Marsh's new KR-2S, it was the first I had heard of any major modifications or improvements to the same old KR design  I believe that article and Roy Marsh's workmanship have probably been the greatest boon to Rand Robinson (RR) in the last twenty years  It certainly caught my eye! Here was the same design I had decided I wanted to build twenty years ago, with all of the improvements I wanted  It was sitting on fixed gear with some reasonable ground clearance  It had the capability to be built large enough to accommodate me  It has enough prefab parts available that it didn't have to be 100% scratch built if I decided to hurry the project along  And it had the speed I wanted  I knew that Roy's published speeds were probably not realistic expectations for the average KR, but after knocking around for the last three years in my Champ, anything over 90 mph seems pretty fast to me 
After purchasing the info kit and the sales video from Rand Robinson, the next step after deciding for sure to build this plane was to order the KR-2 plans and the KR-2S addendum  I finally got my plans and was putting together my first order to start the plane, when my partner in the Champ pointed out that there was a partially completed KR-2S for sale in Trade-a-plane  My initial answer was "No, I don't even want to look at it  I want to build my own from scratch " My partner insisted that for the advertised price and the fact that it wasn't too far away, I ought to at least give the guy a call and investigate it  "No, I don't think I want to buy someone else's problems," I persisted  That night I went home and crunched up some numbers on the calculator and finally came to the conclusion that for the sake of my budget for the next several years, I really should give this guy a call 
Three days later, I flew to his place about 400 miles away to take a look at his project  At this point I should probably mention that I consider myself to be fairly knowledgeable about airplane construction, although the vast majority of my experience is with tube and fabric  The rest of this article deals with what I looked for and more importantly what I missed and have had to repair in the last year since I purchased the project 
When we went to the seller's house, I found that the left wing was built using the Dan Diehl wing skins and the right wing skins were leaning against the wall inside the house  Also the canopy was in the house with the canopy covered with paper and tape  I wanted to inspect the fuselage first, so off we went to the shop 
There I found a fuselage sitting on it's gear painted in primer gray  The first step was to inspect the quality of workmanship of what could be seen as it sat  The interior of the fuselage looked as if it had been built with a great deal of care  The fit and finish of all of the interior wood was very nice  Even the gussets looked like they had been painstakingly perfectly fitted  The glass work on the turtle back also looked very precise and clean  It was evenly faired into the vertical and horizontal stabs  The tail also appeared to be well built with the exception of a depression directly over the front and rear spars in the horizontal stabs  He explained that when he moved recently, that he had shot the plane with gray primer to protect it from the weather since he wouldn't have ready access to a shop to put it in right away  It ended up sitting out in the hot south Texas summer sun for a few weeks before he got a shop rented to work in  That caused the glass (or possibly the foam inside the horizontal stab) to swell, except that it held onto the spar, so it was slightly ballooned in front of and behind the spars  His recommendation was to fill it back smooth with micro 
I also found a small linear crack in the lower left wing spar cap on the left wing stub  It appeared to be from over tightening the rear spar wing attach fitting bolts  His explanation was that the crack wasn't important because the rear spars only job is to keep the wings from folding back  I also noticed that the holes for attaching the outer wing to the wing stub were badly rounded out on the rear spar  He explained that the Diehl wing skins require the rear spar to be swept slightly more forward than the stock wings  This won't allow you to use the rear spar attach fittings from RR and that I would need to fabricate a new set of rear spar attach fittings 
I also found that the aileron bellcranks were not built or installed as per plans, but found that they looked professional  I couldn't check for function since the right bellcrank and sheeve wasn't installed, the left wing also wasn't installed, and the right wing didn't exist yet 
Next we pulled the inspection panels off of the fuselage and tail and looked at everything I could see with a good flashlight  I didn't find anything else that might be questionable about the fuselage except for a cracked elevator trim tab that was damaged when it fell off it's hanging place on the wall 
Next we spent some time going over his builders log and builders photo album  I still hadn't seen anything that would dissuade me from buying this project 
At this point it was starting to get late and my ride down needed to get airborne for the flight home  I needed to make a decision about whether I wanted this project or not, but I hadn't inspected the wings and canopy yet  I took a cursory look at the left wing and saw lots on micro built up on it and some bubbles in the leading edge, but nothing that looked seriously wrong to my amateur eye  The right wing was only a set of spars in the shop and the Diehl wing skins in the house, so there wasn't much to look at there  The canopy was wrapped in paper and tape, so there wasn't much to look at there either  I decided that even if there were serious problems in the wing that was built, I would be money ahead to go ahead and buy the project  For the advertised price, I could build a new set of wings and still be way ahead financially  We negotiated a final price, shook hands, took my ride to the airport, and started off in search of a U-haul to haul the project home 
Now, at this point, some of you are thinking about what I surely must have forgotten to inspect and why didn't I take a local A & P or EAA member along for the ride  First of all, I don't know any mechanics locally that have any experience with glass and our EAA chapter of which I am VP is woefully lacking in fiberglass knowledge  Secondly, as you will see, I missed plenty  Some by ignorance, some by just not looking close enough 
Now for a list of the problems that I found over the last year and a few of the fixes that I came up with 
I found that the lower set of rear spar attach fittings on the left rear spar were installed backwards with the longer spaced hole towards the fuselage  Since this is the same place that also had the cracked spar cap, it required a major change  Also in the same area he had drilled through the rear spar with a hole saw to create a place for the aileron cable to pass through and managed to cut out the second from the outside vertical brace in the spar  Then he chose to install the aileron bellcranks in front of the rear spar, and cut another hole through the rear spar for the aileron push rod  He also managed to cut out the outside vertical brace in the spar  Since the holes were already drilled through the spar, the choices were to either cut out that section of spar cap and scarf a new piece in, cut the whole rear spar carrythrough out of the fuselage including ruining the left lower wing skin, or do something else creative to reinforce the spar cap and install a custom built set of attach fittings 
I also found that after I built and installed the right side wing stub ribs and skin that the aileron bellcrank setup would not work as installed  The cable that crosses between the two bellcranks had a sharp uphill from the sheeve to the bellcrank in the last 12 inches on either side  This combined with the radius that the bellcranks turn caused the cross cable to pull up tight when the ailerons were pushed to either end of their travel, but allowed the cables to go very slack when the ailerons were centered  Also the Aileron pushrods needed to pass directly through the lower set of rear wing attach fittings to attach to the aileron  This whole rear spar and aileron bellcrank setup was going to either have to be redesigned or cut out and built to plans  The bottom line is that the problems I observed when I inspected this part were much more serious than expected when I had to fix it 
I decided that I had to remove the rear fittings from the left wing to be replaced with the new set that my neighborhood machinist was cutting out for me  When I put the wing on the work bench to start removing the rear fittings, I thought I had better take a closer look at the bubbles in the leading edge  I found that as I pushed on the leading edge, it delaminated between the glass lay-up on top and the upper and lower wing skin edges that were floxed together underneath  I concluded that that area had to come apart and took a belt sander to the leading edge  What I found was that the leading edge had been floxed together and glassed over, but the mold release had never been scrubbed off the leading edge of the wing  It peeled apart for rebuild quite easily 
When I got back to removing the rear spar attach fittings, I noticed that the woodwork inside the wing looked awfully dull  The reason was that the wing had been closed up without varnishing any of the woodwork  This was rectified with a small hole saw, a number of extensions and a modified undercoating sprayer 
I also found that the aluminum drain fitting in the bottom of the left wing tank had been glassed into place upside down  The tapered pipe threads were tapered the wrong way to install the draincock into the tank  Retapping the fitting the right direction seemed to be a good fix for that problem 
When I finally got around to attaching the wing to the fuselage, I found that the front spar attach fittings were badly misaligned  Although they could be forced into alignment, I didn't think I needed that kind of preload on the main spar fittings  This problem was fixed by calling on my local neighborhood machinist to build me an aligning fixture and reaming the attach holes to the next larger size and ordering the new sized bolts 
On the fuselage I found that although it had new Cleveland wheels and brakes on it, one of the brakes had a severe wobble to it  I must complement the manufacturers for taking care of that problem  One call to the Cleveland factory and they shipped me a new set of wheels and brakes even though the receipt for this set was over four years old and in the original builders name  Their only concern was that this set had never been placed in service yet 
I chose to sand the load of micro off the left wing to see what it was covering  When I got down to the glass, I found that there was no glass for the aft inch and a half of the underside of the wing in front of the aileron hinge  With the Diehl wing skins, you build the wings, then cut the ailerons out of trailing edge of the wing  He had mismeasured and cut too much material off the bottom side of the trailing edge in front of the aileron  It was filled by floxing a piece of spruce into the gap to fill the space between the back edge of the fiberglass and the aileron mount  I chose to wrap the trailing edge of that wing, and the other wing to match with a couple of lay-ups of glass 
When I sanded the primer off the aforementioned damaged trim tab, I found that the hinge was floxed to the leading edge of the foam insides of the tab, but not the glass  I also chose to wrap the front of the trim tab with a lay-up of glass 
I decided to pull the paper off the canopy and take a look at it before I'm ready to bolt it on and fly  The original builder had blown his own canopy and after some of the previous problems, I was beginning to have some concerns about not having looked it over closely enough  The canopy turned out to have been blow a little too large  It ended up with a little larger bubble for headroom, which I didn't object to  However, it had more headroom on the right side than the left  Yes, it was just a little bit lopsided  The main problem was that the canopy is stretched thin enough that it can be easily pushed in with one hand when the weather is warm   My fear was that this is just thin enough that it may decide to lay on my head or in my lap when flying on a warm day  It will have to be replaced 
I'm sure that many that are reading this could see several of the potential problems before I mentioned them, but some others may not have and I'm sure that there could have been many other problems that didn't but could have existed on this project  This is also not intended to be critical of the gentleman that started this project as many parts of it, especially the wood work are better than I could have done and much of his work is outstanding  I prefer to think that I'll end up with a better plane with his woodwork combined with my glasswork  This article is intended to feature some of the problems that you may run into in buying someone else's project 
The final question is, knowing what I have found over the past year, would I have still purchased this project  The answer is yes, but primarily because the price was right in that I am still money and work ahead of where I would be if I had started the project from scratch  There are a few things that I would have done differently, but nothing that I can't live with  Although I won't be able to say that I built it all from scratch, I have built and rebuild enough of the plane that I should have no problem qualifying under the 51% rule 
You can send comments directly to the author via e-mail at "jscott@LANL GOV" 
Here is an brief explanation of how I built my turtledecks  The jig was constructed from scrap plywood and a few 1x4s that I ripped into stringers  I made two temporary bulkheads from the plywood, one for each end  Remember the forward bulkhead needs to be shaped in a way that will closely match the aft end of your canopy frame  Make an aft bulkhead by placing a straight edge at the top of your forward bulkhead and the trailing edge of your horizontal stabilizer  This will give you an idea of how tall your aft bulkhead needs to be  As far as location, I placed my aft bulkhead just forward of the lower/front of my vertical fin  I constructed the jig on the fuselage, it is glued together with automotive bondo 
After the bulkheads were bondoed to the fuselage I used the stringers that I ripped from the 1x4s and bondoed them to the bulkheads  This gave me a male form to cover with thin plastic or posterboard  I stapled two layers of posterboard to the jig(thin plastic would work better)  The posterboard wraps down two inches onto the fuselage  After I was satisfied with the way it looked, I then covered the entire thing with duct tape (fiberglass will not stick to duct tape) On top of this I wetout one layer of tri-ply cloth (22oz) that I had left over from an earlier project, and one layer of 8oz  bid  Remember to mask off your fuselage so you don't get epoxy on it  If you are not familiar with composite lay-ups, you should plan on razor cutting your lay-ups 4 to 6 hours after wetout while the lay-up is still soft enough to cut with a razorblade 
After the lay-up cured (2 or 3 days) it was removed from the jig, and the jig was removed from the fuselage and discarded  (be careful, the bondo sticks very well to the spruce, you could splinter your wood during removal) I now have a fiberglass skin that tends to hold the shape of the jig but is still flexible enough to work with  I made two bulkheads out of 1/4 last-a-foam (AS&S) using the plywood formers from the jig as a guide  I covered these foam bulkheads with one 8oz layer of glass on each side, with a glass to glass edge on the bottom  After cure these bulkheads were bondoed into place (to the fuselage)and the fiberglass skin was pulled down tight and floxed to the bulkheads  When the flox cured the bondo joints were broken, again being careful not to harm the wood  The turtledeck was removed from the fuselage and 2 inch tapes added to the bulkheads inside and out 
At this point the turtledeck looked great and only weighed about 5lbs  but I noticed you could deform the skin by pushing hard on the outside  So I flipped the turtledeck over and from 1/4 inch last-a-foam, I cut two inch wide strips that would run the entire length, forward and aft inside the turtledeck  In effect these would act as composite stringers, I made enough of these two inch wide strips to make up three stringers  One down the center (sort of a backbone) and one on each side of the "backbone" half the distance to the edge of the turtledeck  I sanded the edge of the foam so that when covered with a layer of bid @ 45degrees there would be a nice transition from the turtledeck skin up onto the foam and then back onto the turtledeck I scuff sanded and glued the foam stringers in with micro  I covered the foam stringers with one layer of 8oz bid @ 45degrees 



ground_truth: The sides of the fuselage are sloped to create a conical section when the fuselage is formed.