IACR News item: 30 January 2024
Ehsan Ebrahimi
ePrint Report
We argue that there are some scenarios in which
plausible deniability might be desired for a digital signature
scheme. For instance, the non-repudiation property of conventional
signature schemes is problematic in designing an Instant
Messaging system (WPES 2004). In this paper, we formally
define a non-binding signature scheme in which the Signer
is able to disavow her own signature if she wants, but, the
Verifier is not able to dispute a signature generated by the
Signer. That is, the Signer is able to convince a third party
Judge that she is the owner of a signature without disclosing
her secret information. We propose a signature scheme that
is non-binding and unforgeable. Our signature scheme is post-quantum secure if the underlying cryptographic primitives are post-quantum secure. In addition, a modification to our nonbinding
signature scheme leads to an Instant Messaging system
that is of independent interest.
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