A Group Signature Scheme with Efficient Membership Revocation for Middle-Scale Groups

This paper proposes a group signature scheme with efficient membership revocation. Though group signature schemes with efficient membership revocation based on a dynamic accumulator were proposed, the previous schemes force a member to change his secret key whenever he makes a signature. Furthermore, for the modification, the member has to obtain a public membership information of O( nN) bits, where n is the length of the RSA modulus and N is the total number of joining members and removed members. In our scheme, the signer needs no modification of his secret, and the public membership information has only K bits, where K is the maximal number of members. Then, for middle-scale groups with the size that is comparable to the RSA modulus size (e.g., up to about 1000 members for 1024 bit RSA modulus), the public membership information is a single small value only, while the signing/verification also remains efficient. key words: group signature, membership revocation, strong RSA assumption