An authorized group signature system and method

Abstract

The invention discloses an authorizable group signature system and method. The system includes a group administrator, a group user, and a user outside the group; The user key of the group member, and is responsible for the initialization of the public-private key pair of the group, the generation of the user key of the group member, and the revocation operation of the group member; the user key of the group member includes the signature key and the disclosure key. Key; group users are general users of the group. After joining the group, they will obtain their own user key through the group administrator, and can perform operations such as signing, verifying signatures, and revealing the signer; outside the group Users can verify messages and signatures through the public key disclosed by the group. The invention can realize the anonymity facing outside the group and the traceability facing inside the group.

Description

technical field [0001] The invention belongs to the technical field of cryptography, and relates to a group signature system and method, in particular to an authorizable group signature system and method. Background technique [0002] With the rapid development of applications related to group cooperation, people realize that signature mechanisms are needed to verify the legitimacy of identities and utilize their traceability and non-repudiation functions. Group members do not want the outside world of the group to be able to obtain the exact identity of the signer. This led to the birth of group signatures. The goal of group signature is to use the group to hide the signer's identity, and to get the real signer through the open operation when needed. [0003] The development of group signature (or anonymous signature mechanism based on group public key) can be roughly divided into four stages. The first stage is before 1999. Chaum and Heyst proposed the concept of group...

AI Technical Summary

Problems solved by technology

In 2001, Kim et al. proposed the first group signature scheme that can revoke group members, but the effect is not good

[0004] However, none of the existing group signature schemes can solve the following problems at the same time: 1) Group members cannot trace the identity of the signer when they are offline (without the assistance of an administrator), that is, offline traceability; 2) Update users after revoking them The key requires a secure channel; 3) It is not possible to further restrict the permissions of group members

[0005] It should be noted that although the group signature can make all group members have the ability to trace the identity of the signer by publicly opening the key in the group, this will make it difficult to track the betrayer in the group. In addition, when revoking, you need to Establish a secure channel between administrators and unrevoked users

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