## 2 Related Work
Apart from the high overhead incurred being the same as the hybrid scheme, due to the use of Merkle tree nodes per page, it is also vulnerable to DoS attack, as an intruder can easily attack the dissemination protocol by halting the transmission of hash packets, which are sent _a priori_. [PERSON] _et al_. have proposed Seltage [12], where they have used a new, efficient pattern for constructing hash values out of the data packets. Figure 1 illustrates their protocol and describes the pattern this scheme uses. The hash value of each packet in page P is inserted to its corresponding packet in the previous page (P-1). This procedure takes place, until all the hash values of the packets from the last page to the first page are created and placed in their relative packets. Seltage proposes to attach all the hash values of page 1 sequentially to create \(HashValues=H(Pkt_{1,1})\cdots H(Pkt_{1,N})\), and then, these values will be split into \(M=2^{k}\) fragments, where K will be the minimum value that fits in Equation (1). Note that resulting M is the number of leaf nodes of the Merkle hash tree (Figure 2). \(|H(. )|\) is the block length of the hash algorithm in bytes. For example, 128-bit MD5 will be denoted as \(|H(. )|\)=16, and N is the number of packets in each page. \[\frac{(N\times|H(.)|)}{2^{K}}+K\times|H(.)|\leq MaximumPayloadSize \tag{1}\]Note that maximum payload size in IEEE 802.15.4 compliant radios is defined to be 102 bytes per packet. Figure 1: Authentication and integrity check of the code image in Seluge (adapted from [12]). Figure 2: The structure of the Merkle hash tree used in Seluge (adapted from [12]). \begin{table}
\begin{tabular}{l l l l l l l l l l l} \hline \hline
**Name** & **Privacy** & **Authentication** & **Integrity** & **DoS Resilience** & **Wormhole** & **Replay** & **Battery-Drain** & **Overhead** & **Comments** \\  & **/Confidentiality** & & & & & & & & & \\ \hline Deuge [23] & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & Efficient \\  & & & & & & & & & & & Reprogramming Scheme \\ Slice [11] & \(\times\) & \(\checkmark\) & \(\checkmark\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & L & - \\ \(\mu\)PKI [21] & \(\checkmark\) & \(\checkmark\) & \(\checkmark\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & VH & - \\ Chain-Based [22] & \(\times\) & \(\checkmark\) & \(\checkmark\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & L & Ordered Delivery of Packets \\ Hash-Tree [22] & \(\times\) & \(\checkmark\) & \(\checkmark\) & \(\times\) & \(\times\) & \(\times\) & VH & - \\ Hybrid [22] & \(\times\) & \(\checkmark\) & \(\checkmark\) & NVG & \(\times\) & \(\times\) & \(\times\) & VH & - \\ Seluge [12] & \(\times\) & \(\checkmark\) & \(\checkmark\) & \(\Lambda\) & \(\checkmark\) & \(\checkmark\) & \(\times\) & VH & Limited Support \\  & & & & & & & & & & for Hash Algorithms \\ Das and & \(\times\) & \(\checkmark\) & \(\checkmark\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & L &
\begin{tabular}{l} Implementation Attack [24] \\ \end{tabular} \\ Joshi Scheme [20] & & & & & & & & & & & \\ \hline \hline \end{tabular}  
* A, acceptable; NVG, not very good; VH, very high; L, low; X, not considered in the design; \(\checkmark\), full preservation.  
\end{table} 
Table 1: A summary of the existing security models for the the over-the-air programming (OTAP) schemes. Seluge also suffers from a security limitation and a high overhead, which will be discussed later in Sections 3 and 8. Existing security models for OTAP schemes are summarized in Table 1. Note that Deluge in the first row of Table 1 is not a security model and is the basic infrastructure used in all the discussed security models. The authors of Deluge have not considered any security principles while designing Deluge; therefore, this OTAP scheme has posed high security risks and is vulnerable to all types of attacks. This fact in Table 1 is shown by adding a cross for all cells of Deluge's row.