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Threshold Cryptography Secure Against the Adaptive Adversary, Concurrently
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| Abstract: | A threshold cryptosystem or signature scheme is a system with $n$ participants where an honest majority can successfully decrypt a message or issue a signature, but where the security and functionality properties of the system are retained even as the adversary corrupts up to $t$ players. We present the novel technique of a committed proof, which is a new general tool that enables security of threshold cryptosystems in the presence of the adaptive adversary. We also put forward a new measure of security for threshold schemes secure in the adaptive adversary model: security under concurrent composition. Using committed proofs, we construct concurrently and adaptively secure threshold protocols for a variety of cryptographic applications. In particular, based on the recent scheme by Cramer-Shoup, we construct adaptively secure threshold cryptosystems secure against adaptive chosen ciphertext attack under the DDH intractability assumption. |
BibTeX
@misc{eprint-2000-11363,
title={Threshold Cryptography Secure Against the Adaptive Adversary, Concurrently},
booktitle={IACR Eprint archive},
keywords={cryptographic protocols / threshold cryptography; adaptive adversary},
url={http://eprint.iacr.org/2000/019},
note={Part of this paper will appear in Eurocrypt2000 anna@theory.lcs.mit.edu 11090 received 12 May 2000},
author={Anna Lysyanskaya},
year=2000
}