# Recursive cheating strategies for the relativistic $\mathbb F_Q$ bit commitment protocol

Abstract : In this paper, we study relativistic bit commitment, which uses timing and location constraints to achieve information theoretic security. We consider the FQ multi-round bit commitment scheme introduced by Lunghi et al. [LKB + 15]. This protocol was shown secure against classical adversaries as long as the number of rounds m is small compared to √ Q where Q is the size of the used field in the protocol [CCL15, FF16]. In this work, we study classical attacks on this scheme. We use classical strategies for the CHSHQ game described in [BS15] to derive cheating strategies for this protocol. In particular, our cheating strategy shows that if Q is an even power of any prime, then the protocol is not secure when the number of rounds m is of the order of √ Q. For those values of Q, this means that the upper bound of [CCL15, FF16] is essentially optimal.
Type de document :
Article dans une revue
MDPI - Cryptography, 2017, 〈10.3390/cryptography1020014〉
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https://hal.inria.fr/hal-01409563
Contributeur : André Chailloux <>
Soumis le : mardi 6 décembre 2016 - 13:30:51
Dernière modification le : samedi 23 décembre 2017 - 01:17:37
Document(s) archivé(s) le : mardi 21 mars 2017 - 09:08:20

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Rémi Bricout, André Chailloux. Recursive cheating strategies for the relativistic $\mathbb F_Q$ bit commitment protocol. MDPI - Cryptography, 2017, 〈10.3390/cryptography1020014〉. 〈hal-01409563〉

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