Cryptology ePrint Archive: Report 2007/080

Weakly only Unforgeable Signature and Its Application in Group Signature

Sujing Zhou, Dongdai Lin

Abstract: If a signature scheme is secure in the sense that no forgery on any new message (i.e., a message that has never been signed) is available for any computation restricted adversary, it is said weakly unforgeable (wUF), in contrast to strongly unforgeable (sUF) meaning no new signature on any old message (i.e., a valid signature on the message is already known) is available to such adversaries. sUF signatures are generally considered advantageous over wUF ones because of preference for high level security. But the case may be different when they are employed to construct group signatures.

wUF but not sUF signatures, called WoUF signatures in this paper, are investigated in this paper. It is found that by applying a generic construction to WoUF signatures with indirectly-signability and perfectly-unlinkability (also defined in this paper), we can regenerate many efficient group signatures in literature.

We also propose improvements to the group signature schemes of CL04, NSN04, KY05, in line with our generic construction.

Category / Keywords: Digital Signature, Group Signature, Weakly Unforgeable Signature, Strongly Unforgeable Signature.

Date: received 1 Mar 2007, withdrawn 30 Mar 2007

Contact author: zhousujing at is iscas ac cn

Available format(s): (-- withdrawn --)

Note: Welcome for any comments.

Version: 20070330:070712 (All versions of this report)

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