International Association for Cryptologic Research

International Association
for Cryptologic Research

CryptoDB

Pierre Karpman

Publications

Year
Venue
Title
2021
EUROCRYPT
Fast verification of masking schemes in characteristic two
Nicolas Bordes Pierre Karpman
We revisit the matrix model for non-interference (NI) probing security of masking gadgets introduced by Belaïd et al. at CRYPTO 2017. This leads to two main results. 1) We generalise the theorems on which this model is based, so as to be able to apply them to masking schemes over any finite field --- in particular GF(2)--- and to be able to analyse the *strong* non-interference (SNI) security notion. We also follow Faust et al. (TCHES 2018) to additionally consider a *robust* probing model that takes hardware defects such as glitches into account. 2) We exploit this improved model to implement a very efficient verification algorithm that improves the performance of state-of-the-art software by three orders of magnitude. We show applications to variants of NI and SNI multiplication gadgets from Barthe et al. (EUROCRYPT~2017) which we verify to be secure up to order 11 after a significant parallel computation effort, whereas the previous largest proven order was 7; SNI refreshing gadgets (ibid.); and NI multiplication gadgets from Gross et al. (TIS@CCS 2016) secure in presence of glitches. We also reduce the randomness cost of some existing gadgets, notably for the implementation-friendly case of 8 shares, improving here the previous best results by 17% (resp. 19%) for SNI multiplication (resp. refreshing).
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