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(2005 / vol.8 / no.1)
Accountable Signatures
Jung Hee Cheon, Woo-Hwan Kim, Hyojin Yoon
Pages. 29-43     



We propose a new notion of {em accountable signatures} in which
related signatures form a signature chain consisting of a root
signature and subsequent signatures.
In a signature chain, each subsequent signature is indexed and if
distinct messages are signed along with the same index, the
signer's secret key is revealed. Accountable signature is an
extension of emph{$k$-times signatures} in which a signer is
enforced not to generate signatures more than $k$ and the
signature and the certificate size and the verification cost is
constant with respect to $k$. We give an instance of accountable
signatures based on a Gap Diffie-Hellman group and prove its
security against adaptive chosen-[index, root signature, and
message] attack in the random oracle model under the
Diffie-Hellman assumption. Further, we show that our accountable
signature admits secure batch verification of many signatures
almost at one verification cost with small security loss.



1. Introduction
2. Formal Definitions
3. An Accountable Signature Scheme
4. Batch Verification of a Signature Chain
5. Conclusion and Further Studies