A Rational Secret-Sharing Scheme Based on RSA-OAEP

Toshiyuki ISSHIKI  Koichiro WADA  Keisuke TANAKA  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E93-A   No.1   pp.42-49
Publication Date: 2010/01/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E93.A.42
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Public Key Cryptography
secret sharing,  game theory,  fairness,  RSA,  OAEP,  

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In this paper, we propose a rational m-out-of-n secret sharing scheme, a dealer wishes to entrust a secret with a group of n players such that any subset of m or more players can reconstruct the secret, but a subset of less than m players cannot learn anything about the secret. The reconstruction protocol of our scheme is fair and stable in the rational settings, allowing all players to obtain the designated secret. Our scheme is based on RSA-OAEP with the distributed decryption. The security of our scheme relies on a computational assumption and uses the random oracles. The size of each share in our scheme is independent of the utility function and the computation cost of the reconstruction protocol is constant. Moreover, our scheme prevents the attacks with at most m-1 coalitions.