# A Survey of Internet of Things (IoT) Authentication Schemes +
## 7 Conclusions
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Ref\#** & **IoT Layer** & **Identity Context Credentials** & **Token Based?** & **Proc.** & **Arch.** & **HW.** & **Strength(+)/Weakness(–)** \\ \hline
[78] & N + P & Encryption/Asymmetric + Hashing & x & & 2 & C/F & I & \(-\)Increase the computation overhead although it is balanced between sender and receiver & \(-\)Storage cost is high & \(-\)The distribution of the public key via secure channel is done before the complete consumption of the hash chains. \\ \hline
[70] & N + P & Encryption/Symmetric + Asymmetric + Hashing & x & & 2 & C/F & I & \(+\)Efficient with respect to computation and communication overhead. \\  & & & & & & & \(-\)Most of the routing attacks are not considered. \\ \hline
[71] & N + P & Encryption/Asymmetric + Hashing & x & & 2 & C/F & I & \(+\)Computation and communication cost is efficient & \(+\)Fault tolerance Architecture. \\  & & & & & & & \(-\)Attacks and threats analysis is not considered. \\ \hline
[72] & N + P & Encryption/Asymmetric + Hashing & ✓(Node ID) & 3 & C/F & I & \(+\)Resistance to DoS, MITM, Brute force and Replay attacks & \(+\)Secure key management. \\  & & & & & & & \(+\)Computation and communication cost is efficient. & \(-\)Confidentiality and Integrity are not considered \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._ \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Ref\#** & **IoT Layer** &
\begin{tabular}{c} **Identity Context** \\ **Credentials** \\ \end{tabular} & **Token Based?** & **Proc.** & **Arch.** & **HW.** & **Strength(+)/Weakness(\(-\))** \\ \hline
[73] & N + P & \
\begin{tabular}{c} Encryption/Asymmetric + \\ Hashing \\ \end{tabular} & ✓ (Identity) & 2 & C/F & I &
\begin{tabular}{c} +Efficient with respect to the success rate \\ +Identity privacy is considered \\ +Message overhead is low \\ \(-\)Routing attacks are not considered \\ \(-\)Storage cost is not considered \\ \end{tabular} \\ \hline
[74] & N + P & \
\begin{tabular}{c} Encryption/symmetric + \\ Asymmetric + Hashing \\ \end{tabular} & x & 2 & C/F & I &
\begin{tabular}{c} +Resistance to Replay, collision, and \\ chosen-plain-text attacks. \\ \(-\)Location and Identity privacy is not considered \\ \end{tabular} \\ \hline
[75] & N + P & \begin{tabular}{c} Encryption/Asymmetric + \\ Hashing \\ \end{tabular} & \
\begin{tabular}{c} ✓ (Entity Id and \\ Serial number) \\ \end{tabular} & 2 & C/F & I &
\begin{tabular}{c} + Resistance to Impersonation, Brute force, \\ DoG, MITM, and Replay attacks \\ +Reducing management cost \\ \(-\)Storage cost is not considered \\ \end{tabular} \\ \hline
[116] & N + P & \begin{tabular}{c} Encryption/ \\ Asymmetric(chaotic map) + \\ Hashing \\ \end{tabular} & \
\begin{tabular}{c} ✓ (Identity id and \\ password) \\ \end{tabular} & 2 & C/H & I &
\begin{tabular}{c} + User is anonymous \\ +Identity privacy is considered \\ +Secure session key \\ +Computation, communication and \\ storage costs are considered \\ \(-\)Data integrity is not considered \\ \end{tabular} \\ \hline
[117] & A + N + P & \
\begin{tabular}{c} Encryption/symmetric + \\ Asymmetric + Hashing \\ \end{tabular} & ✓ (Identity) & 2 & D /H & I &
\begin{tabular}{c} +Resistance to Password guessing, \\ session-key attacks \\ +Computation cost is considered \\ \(-\)Location privacy and communication \\ cost are not considered \\ \end{tabular} \\ \hline
[117] & A + N + P & \
\begin{tabular}{c} Encryption/symmetric + \\ Asymmetric + Hashing \\ \end{tabular} & ✓ (Identity) & 2 & D /H & I &
\begin{tabular}{c} +Resistance to Password guessing, \\ session-key attacks \\ +Computation cost is considered \\ \(-\)Location privacy and communication \\ cost are not considered \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._