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2016 | OriginalPaper | Chapter

Legally Fair Contract Signing Without Keystones

Authors : Houda Ferradi, Rémi Géraud, Diana Maimuț, David Naccache, David Pointcheval

Published in: Applied Cryptography and Network Security

Publisher: Springer International Publishing

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Abstract

In two-party computation, achieving both fairness and guaranteed output delivery is well known to be impossible. Despite this limitation, many approaches provide solutions of practical interest by weakening somewhat the fairness requirement. Such approaches fall roughly in three categories: “gradual release” schemes assume that the aggrieved party can eventually reconstruct the missing information; “optimistic schemes” assume a trusted third party arbitrator that can restore fairness in case of litigation; and “concurrent” or “legally fair” schemes in which a breach of fairness is compensated by the aggrieved party having a digitally signed cheque from the other party (called the keystone).

In this paper we describe and analyse a new contract signing paradigm that doesn’t require keystones to achieve legal fairness, and give a concrete construction based on Schnorr signatures which is compatible with standard Schnorr signatures and provably secure.

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See [17] for a very specific case where completely fair two-party computation can be achieved.

In a number of cases, e.g. DSA, the formulae of s do not lend themselves to security proofs.

The algorithm \(\mathsf {KeyGen}\) being public, \(\mathcal A\) can compute \(\mathsf {KeyGen}(k)\) for any k of her choosing.

Note that with this information and using KeyGen queries, \(\mathcal A\) can obtain concurrent signatures for any message and any user pair.

In a number of cases, e.g. DSA, the formulae of s do not lend themselves to security proofs.

The key \(y_U^{(2)}\) may be derived from \(y_U^{(1)}\) in some way, so that the storage needs of \(\mathcal D\) are the same as for classical Schnorr.

In particular, the question of whether Bob “intended” to sign is outside the scope of this security model.

If Bob transmits a wrong or incorrect \(s_B\), this will be immediately detected by Alice as \(r_B \ne g^{s_B} y_B^e\). Naturally, in such a case, Bob never sent any information binding him to the contract anyway.

Abe, M., Ohkubo, M., Suzuki, K.: 1-out-of-n signatures from a variety of keys. In: Zheng, Y. (ed.) ASIACRYPT 2002. LNCS, vol. 2501, pp. 415–432. Springer, Heidelberg (2002)CrossRef

Asokan, N., Schunter, M., Waidner, M.: Optimistic protocols for fair exchange. In: ACM CCS 1997: 4th Conference on Computer and Communications Security, pp. 7–17. ACM Press, Zurich 1–4 April 1997

Baum-Waidner, B., Waidner, M.: Round-optimal and abuse-free optimistic multi-party contract signing. In: Welzl, E., Montanari, U., Rolim, J.D.P. (eds.) ICALP 2000. LNCS, vol. 1853, pp. 524–535. Springer, Heidelberg (2000)CrossRef

Ben-Or, M., Goldwasser, S., Wigderson, A.: Completeness theorems for non-cryptographic fault-tolerant distributed computation (extended abstract). In: 20th Annual ACM Symposium on Theory of Computing, pp. 1–10. ACM Press, Chicago 2–4 May 1988

Cachin, C., Camenisch, J.L.: Optimistic fair secure computation. In: Bellare, M. (ed.) CRYPTO 2000. LNCS, vol. 1880, pp. 93–111. Springer, Heidelberg (2000)CrossRef

Chaum, D., Crépeau, C., Damgård, I.: Multiparty unconditionally secure protocols (extended abstract). In: 20th Annual ACM Symposium on Theory of Computing, pp. 11–19. ACM Press, Chicago 2–4 May 1988

Chen, L., Kudla, C., Paterson, K.G.: Concurrent signatures. In: Cachin, C., Camenisch, J.L. (eds.) EUROCRYPT 2004. LNCS, vol. 3027, pp. 287–305. Springer, Heidelberg (2004)CrossRef

Cleve, R.: Limits on the security of coin flips when half the processors are faulty (extended abstract). In: Hartmanis, J. (ed.) Proceedings of the 18th Annual ACM Symposium on Theory of Computing, May 28–30, Berkeley, California, USA, pp. 364–369. ACM (1986)

El Gamal, T.: A public key cryptosystem and a signature scheme based on discrete logarithms. In: Blakely, G.R., Chaum, D. (eds.) CRYPTO 1984. LNCS, vol. 196, pp. 10–18. Springer, Heidelberg (1985)CrossRef

10.

Garay, J.A., Jakobsson, M., MacKenzie, P.D.: Abuse-free optimistic contract signing. In: Wiener, M. (ed.) CRYPTO 1999. LNCS, vol. 1666, pp. 449–466. Springer, Heidelberg (1999)

11.

Garay, J.A., MacKenzie, P.D., Prabhakaran, M., Yang, K.: Resource fairness and composability of cryptographic protocols. In: Halevi, S., Rabin, T. (eds.) TCC 2006. LNCS, vol. 3876, pp. 404–428. Springer, Heidelberg (2006)CrossRef

12.

Girault, M., Poupard, G., Stern, J.: On the fly authentication and signature schemes based on groups of unknown order. J. Cryptology 19(4), 463–487 (2006)MathSciNetCrossRefMATH

13.

Goldreich, O.: A simple protocol for signing contracts. In: Chaum, D. (ed.) CRYPTO 1983, pp. 133–136. Plenum Press, New York (1983)

14.

Goldreich, O.: Foundations of Cryptography: Basic Applications, vol. 2. Cambridge University Press, Cambridge (2004)CrossRefMATH

15.

Goldreich, O., Micali, S., Wigderson, A.: How to play any mental game or a completeness theorem for protocols with honest majority. In: Aho, A. (ed.) 19th Annual ACM Symposium on Theory of Computing, pp. 218–229. ACM Press, New York 25–27 May 1987

16.

Goldwasser, S., Levin, L.A.: Fair computation of general functions in presence of immoral majority. In: Menezes, A., Vanstone, S.A. (eds.) CRYPTO 1990. LNCS, vol. 537, pp. 77–93. Springer, Heidelberg (1991)

17.

Gordon, S.D., Hazay, C., Katz, J., Lindell, Y.: Complete fairness in secure two-party computation. In: Ladner, R.E., Dwork, C. (eds.) 40th Annual ACM Symposium on Theory of Computing, pp. 413–422. ACM Press, Victoria 17–20 May 2008

18.

Horster, P., Petersen, H., Michels, M.: Meta-El-Gamal signature schemes. In: ACM CCS 94: 2nd Conference on Computer and Communications Security, pp. 96–107. ACM Press, Fairfax (1994)

19.

Jakobsson, M., Sako, K., Impagliazzo, R.: Designated verifier proofs and their applications. In: Maurer, U.M. (ed.) EUROCRYPT 1996. LNCS, vol. 1070, pp. 143–154. Springer, Heidelberg (1996)

20.

Lindell, A.Y.: Legally-enforceable fairness in secure two-party computation. In: Malkin, T. (ed.) CT-RSA 2008. LNCS, vol. 4964, pp. 121–137. Springer, Heidelberg (2008)CrossRef

21.

Micali, S.: Simple and fast optimistic protocols for fair electronic exchange. In: Borowsky, E., Rajsbaum, S. (eds.) 22nd ACM Symposium Annual on Principles of Distributed Computing, pp. 12–19. Association for Computing Machinery, Boston 13–16 July 2003

22.

Pinkas, B.: Fair secure two-party computation. In: Biham, E. (ed.) EUROCRYPT 2003. LNCS, vol. 2656, pp. 87–105. Springer, Heidelberg (2003)CrossRef

23.

Rivest, R.L., Shamir, A., Tauman, Y.: How to leak a secret. In: Boyd, C. (ed.) ASIACRYPT 2001. LNCS, vol. 2248, pp. 552–565. Springer, Heidelberg (2001)CrossRef

24.

Yao, A.C.C.: How to generate and exchange secrets (extended abstract). In: 27th Annual Symposium on Foundations of Computer Science, pp. 162–167. IEEE Computer Society Press, Toronto 27–29 October 1986

Title: Legally Fair Contract Signing Without Keystones
Authors: Houda Ferradi
Rémi Géraud
Diana Maimuț
David Naccache
David Pointcheval
Publisher: Springer International Publishing
Book: Applied Cryptography and Network Security
Print ISBN: 978-3-319-39554-8

Electronic ISBN: 978-3-319-39555-5

Copyright Year: 2016
DOI: https://doi.org/10.1007/978-3-319-39555-5_10

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