Ephemeral Keys Authenticated with Merkle Trees and Their Use in IoT Applications

Public key algorithms based on quasi-cyclic binary moderate-density parity-check codes (QC-MDPCs) and QC low-density parity-check codes (QC-LDPCs) codes for key encapsulation and encryption submitted to the NIST post-quantum competition (Bit Flipping Key Encapsulation (BIKE), QC-MDPC KEM, LEDA) are vulnerable against reaction attacks based on decoding failures. To protect algorithms, authors propose to limit the key usage, in the extreme (BIKE) to only use ephemeral public keys. In some authenticated protocols, we need to combine each key with a signature, which can lead to increased traffic overhead, especially given the large signature sizes of some of the proposed post-quantum signature schemes. We propose to combine ephemeral public keys with a simple Merkle tree to obtain a server authenticated key encapsulation/transport suitable for TLS-like handshake protocols. This allows a very simple public key verification on the client, leading to efficient protocols suitable for Internet of Things applications.

Comparative evaluation of quasi-delay-insensitive asynchronous adders corresponding to return-to-zero and return-to-one handshaking

This article makes a comparative evaluation of quasi-delay-insensitive (QDI) asynchronous adders, realized using the delay-insensitive dual-rail code, which adhere to 4-phase return-to-zero (RTZ) and 4-phase return-to-one (RTO) handshake protocols. The QDI adders realized correspond to the following adder architectures: i) ripple carry adder, ii) carry lookahead adder, and iii) carry select adder. The QDI adders correspond to three different timing regimes viz. strong-indication, weak-indication, and early output. They are physically implemented using a 32/28nm CMOS process. The comparative evaluation shows that, overall, QDI adders which correspond to the 4-phase RTO handshake protocol are better than the QDI adder counterparts which correspond to the 4-phase RTZ handshake protocol in terms of latency, area, and average power dissipation.