Cryptology ePrint Archive: Report 2021/170

Fully Anonymous Group Signature with Verifier-Local Revocation

Ai Kitagawa and Yusuke Sakai and Keita Emura and Goichiro Hanaoka and Keisuke Tanaka

Abstract: Group signature with verifier-local revocation (VLR-GS) is a special type of revocable group sig- nature which enables a user to sign messages without referring to information regarding revoked users. Although there have been several proposals of VLR-GS schemes since the first scheme proposed by Boneh and Shacham [CCS 2004], all of these schemes only achieve a security notion called selfless anonymity, which is strictly weaker than the de facto standard security notion, full anonymity. Thus, for more than a decade, it has been an open problem whether a fully anonymous VLR-GS scheme can be achieved. In this paper, we give an affirmative answer to this problem. Concretely, we show the construction of a fully anonymous VLR-GS scheme from a digital signature scheme, a key-private public key encryption scheme, and a non-interactive zero-knowledge proof system. Also, we show that backward unlinkability, which ensures that even after a user is revoked, signatures produced by the user before the revocation remain anonymous, can be realized without additional building blocks. Although the size of group public key and signing key depend on the number of time periods, finally, we show that the size of these keys can be reduced by employing an identity-based encryption scheme.

Category / Keywords: public-key cryptography / Group Signature, Verifier-Local Revocation, Full Anonymity, Backward Unlinkability

Original Publication (with major differences): SCN 2018

Date: received 16 Feb 2021

Contact author: a kitagawa at aist go jp

Available format(s): PDF | BibTeX Citation

Version: 20210217:125552 (All versions of this report)

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