Scalable Revocable IdentityBased Signature Scheme with Signing Key Exposure Resistance from Lattices In 2014, a new security definition of a revocable identitybased signature (RIBS) with signing key exposure resistance was introduced. Based on this new definition, many scalable RIBS schemes with signing key exposure resistance were proposed. However, the security of these schemes is based on traditional complexity assumption, which is not secure against attacks in the quantum era. Latticebased cryptography has many attractive features, and it is believed to be secure against quantum computing attacks. We reviewed existing latticebased RIBS schemes and found that all these schemes are vulnerable to signing key exposure. Hence, in this paper, we propose the first latticebased RIBS scheme with signing key exposure resistance by using the leftright lattices and delegation technology. In addition, we employ a complete subtree revocation method to ensure our construction meeting scalability. Finally, we prove that our RIBS scheme is selectiveID existentially unforgeable against chosen message attacks (EUFsIDCMA) under the standard short integer solutions (SIS) assumption in the random oracle model.

Loop abort Faults on LatticeBased FiatShamir & Hashn Sign signatures As the advent of generalpurpose quantum computers appears to be drawing closer, agencies and advisory bodies have started recommending that we prepare the transition away from factoring and discrete logarithmbased cryptography, and towards postquantum secure constructions, such as latticebased schemes. Almost all primitives of classical cryptography (and more!) can be realized with lattices, and the efficiency of primitives like encryption and signatures has gradually improved to the point that key sizes are competitive with RSA at similar security levels, and fast performance can be achieved both in software and hardware. However, little research has been conducted on physical attacks targeting concrete implementations of postquantum cryptography in general and latticebased schemes in particular , and such research is essential if lattices are going to replace RSA and elliptic curves in our devices and smart cards. In this paper, we look in particular at fault attacks against some instances of the FiatShamir family of signature scheme on lattices (BLISS, GLP, TESLA and PASSSign) and on the GPV scheme, member of the Hashu0027n Sign family. Some of these schemes have achieved recordsetting efficiency in software and hardware. We present several possible fault attacks, one of which allows a full key recovery with as little as a single faulty signature, and discuss possible countermeasures to mitigate these attacks.