Game-Theoretic Security for Bit Commitment

KEISUKE TANAKA, Kenji Yasunaga

Lu Qun Zhou, Xin Sun, Chunhua Su +2 more

Hao Cao, Wenping Ma, Liangdong Lü +3 more

Tsuyoshi Komatsubara, Yoshifumi Manabe

This paper considers game-theoretic security of bit commitment protocols under a realistic cost model. Higo et. al (IWSEC 2013) proved equivalence of game-theoretic security and cryptographic security of bit commitment protocols under an ideal cost model. Their model assumes that there is no cost for communication and computation. Under a realistic model that cost for communication and computation is non-negligible, this paper shows that conventional bit commitment protocols are not game-theoretically secure, and abort detection property is necessary for bit commitment protocols to achieve game-theoretic security.

Rémi Bricout, André Chailloux

In this paper, we study relativistic bit commitment, which uses timing and location constraints to achieve information theoretic security. Using those constraints, we consider a relativistic bit commitment scheme introduced by Lunghi et al. This protocol was shown secure against classical adversaries as long as the number of rounds performed in the protocol is not too large. In this work, we study classical attacks on this scheme. We use the correspondence between this protocol and the CHSHQ game—which is a variant of the CHSH game—to derive cheating strategies for this protocol. Our attack matches the existing security bound for some range of parameters and shows that the scaling of the security in the number of rounds is essentially optimal.

Haruna Higo, Keisuke Tanaka, Akihiro Yamada +1 more