Paper 2021/992 Original: eprint.iacr.org/2021/992 ↗

Faster Public-key Compression of SIDH with Less Memory

Abstract

In recent years, the isogeny-based protocol, namely supersingular isogeny Diffe-Hellman (SIDH) has become highly attractive for its small public key size. In addition, public-key compression makes supersingular isogeny key encapsulation scheme (SIKE) more competitive in the NIST post-quantum cryptography standardization effort. However, compared to other post-quantum protocols, the computational cost of SIDH is relatively high, and so is public-key compression. On the other hand, the storage for pairing computation and discrete logarithms to speed up the current implementation of the key compression is somewhat large. In this paper, we mainly improve the performance of public-key compression of SIDH, especially the effciency and the storage of pairing computation involved. Our experimental results show that the memory requirement for pairing computation is reduced by a factor of about $1.5$, and meanwhile, the instantiation of key generation of SIDH is $4.06\% ∼ 7.23\%$ faster than the current state-of-the-art.