International Association for Cryptologic Research

International Association
for Cryptologic Research

CryptoDB

Pierre Karpman

Affiliation: Université Grenoble Alpes, France

Publications

Year
Venue
Title
2018
TOSC
Short Non-Malleable Codes from Related-Key Secure Block Ciphers
Serge Fehr Pierre Karpman Bart Mennink
A non-malleable code is an unkeyed randomized encoding scheme that offers the strong guarantee that decoding a tampered codeword either results in the original message, or in an unrelated message. We consider the simplest possible construction in the computational split-state model, which simply encodes a message m as k||Ek(m) for a uniformly random key k, where E is a block cipher. This construction is comparable to, but greatly simplifies over, the one of Kiayias et al. (ACM CCS 2016), who eschewed this simple scheme in fear of related-key attacks on E. In this work, we prove this construction to be a strong non-malleable code as long as E is (i) a pseudorandom permutation under leakage and (ii) related-key secure with respect to an arbitrary but fixed key relation. Both properties are believed to hold for “good” block ciphers, such as AES-128, making this non-malleable code very efficient with short codewords of length |m|+2τ (where τ is the security parameter, e.g., 128 bits), without significant security penalty.
2018
JOFC
2018
ASIACRYPT
New Instantiations of the CRYPTO 2017 Masking Schemes
Pierre Karpman Daniel S. Roche
At CRYPTO 2017, Belaïd et al. presented two new private multiplication algorithms over finite fields, to be used in secure masking schemes. To date, these algorithms have the lowest known complexity in terms of bilinear multiplication and random masks respectively, both being linear in the number of shares $$d+1$$ . Yet, a practical drawback of both algorithms is that their safe instantiation relies on finding matrices satisfying certain conditions. In their work, Belaïd et al. only address these up to $$d=2$$ and 3 for the first and second algorithm respectively, limiting so far the practical usefulness of their constructions.In this paper, we use in turn an algebraic, heuristic, and experimental approach to find many more safe instances of Belaïd et al.’s algorithms. This results in explicit instantiations up to order $$d = 6$$ over large fields, and up to $$d = 4$$ over practically relevant fields such as $$\mathbb {F}_{2^8}$$ .
2017
CRYPTO
2016
EUROCRYPT
2016
ASIACRYPT
2015
EPRINT
2015
EPRINT
2015
EPRINT
2015
EPRINT
2015
EPRINT
2015
CRYPTO
2015
CRYPTO
2015
ASIACRYPT
2014
EPRINT

Program Committees

FSE 2020
FSE 2019
FSE 2018