A New Dynamic Code-Based Group Signature Scheme

摘要

Group signature is a cryptographic primitive where a user can anonymously sign a message on behalf of group users. The dynamic case in group signature is more interesting than the static one. The general idea of this scheme consists in finding a collision between two cipher-texts using two different Quasi-cyclic Moderate Density Parity-Check (QC-MDPC) matrices in McEliece cryptosystem. We use a variation of AGS Zero-Knowledge protocol to prove the possession of the secret key and then we use the Fiat Shamir transformation to turn it into a signature. The public key and signature sizes are constants and independent of group users size and are shorter than those presented in the literature for 80 bits security level. Furthermore the proposed group signature scheme presents several advantages: it is a dynamic group signature based on error correcting code assumptions which are supposed resistant to quantum computing.