# Internet of Things and Blockchain Integration: Security, Privacy, Technical, and Design Challenges
## 2 Background and Related Work
### Blockchain Platforms
#### 2.2.1 Bitcoin Platform  
The first cryptocurrency, as well as the first BC platform, was Bitcoin. It provides a safe payment system that can be embedded into applications to conduct financial transactions quickly and reliably. Autonomous machines can use Bitcoin to make micropayments and act as wallets in the BIoT [51]. Due to the transaction costs charged, it is not financially advantageous to process small payments (i.e., less than $) using the current banking and credit systems. However, with Bitcoin, that is now ridiculously simple. However, due to a variety of factors, including scalability, fees, and block size, the BC platform design  
\begin{table}
\begin{tabular}{l l l l} \hline \hline
**Platform** & **Advantages** & \multicolumn{2}{c}{**Disadvantages**} \\ \hline \multirow{4}{*}{Bitcoin} & \(\bullet\) & Open-source & \(\bullet\) & Low scalability, low security, low privacy, low \\  & \(\bullet\) & P2P network, which allows rapid worldwide & \(\bullet\) & 51\% attack \\  & payments & \(\bullet\) & It is the most secure and widely used BC-based & \(\bullet\) & Loops and recursion are not supported by the \\  & & payment method & \(\bullet\) & Bitcoin script. \\  & & & \(\bullet\) & Limited decentralization \\ \hline \multirow{2}{*}{Ethereum} & \(\bullet\) & Open-source & \(\bullet\) & Medium scalability, low security, low privacy, low \\  & \(\bullet\) & Decentralized P2P network & \(\bullet\) & transaction rate \\ \hline \multirow{4}{*}{HLF} & \(\bullet\) & High privacy, high scalability, high transaction rate & \(\bullet\) & Medium security \\  & \(\bullet\) & Open-source cross-industry standardization & \(\bullet\) & 1/3 fault node attack \\  & \(\bullet\) & Sophisticated data queries and key-value pair data & \(\bullet\) & Complex architecture and lack of use cases \\  & & are supported & & \\ \hline \multirow{4}{*}{Multichain} & \(\bullet\) & Open-source, high security, high privacy, high & \multirow{4}{*}{\(\bullet\)} & Medium transaction rate \\  & \(\bullet\) & scalability & 1/3 fault node attack \\ \cline{1-1}  & \(\bullet\) & Low latency and high throughput & \(\bullet\) & No built-in support for smart contracts \\ \cline{1-1}  & \(\bullet\) & High query functionality and decentralization & \(\bullet\) & No built-in support for smart contracts \\ \hline \hline \end{tabular}
\end{table}
Table 3: Advantages and disadvantages of Bitcoin, Ethereum, HLF, and Multichain BCs’ platforms.  
is not practical for facilitating micropayments [52]. BC solutions should allow many micropayments to be made without the transactions being logged on the main BC [53]. Therefore, the new BC approach recommends grouping up multiple minor transactions into one larger transaction [54].  
When using BC for micropayments, applications are usually tied to the currency, which can be a disadvantage since inflation of the coin can have a detrimental impact on the application. When carrying out transactions, Bitcoin provides a scripting language that enables complex conditions to be set. However, as compared to other smart contract systems, the scripting is very limited [46]. To validate transactions, Bitcoin uses the PoW consensus protocol, which requires substantial resources and energy.