Research On Security Analysis And Improvement Of The Group Signature

This dissertation mainly discusses the security analysis and improvement of the group signature. The firstly advanced parts are two improvement schemes of characteristic secret key renewing algorithm and a novel group signature member deletion scheme in regard to the group signature member deletion scheme based on the knowledge signature. Secondly, an improvement schemes based on uncommon modulus and a novel scheme immune to framing attack from the group center are proposed in regard to the security shortages of the group signature scheme based on Chinese remainder theorem. Thirdly, after researching on NTRU decryption failure compensation scheme, this dissertation puts forward a sort of group signature scheme based on NTRU. Finally, aiming at the secret generation and administration of the group signature scheme, the generation algorithm of the secret sequences, which satisfies the Strict Avalanche Criterion (SAC), is put forward and a key expansion scheme based on DNA coding technology is designed. The main topics of this dissertation are listed as follows:1. The member deletion scheme presented by Wang SP and his team is analyzed in detail and proved to be a failure to delete group members really. By changing the state of renewal operator of member addition and deletion from public to private and changing the renewal characteristic secret key's executor from members to group administrator, the two improvement schemes of characteristic secret key renewing algorithm are presented. Then, by further analysis and study, another novel scheme of group signature member deletion is advanced, and the secret characteristic keys of all legal group members are not needed to change when to add or delete a group member from the novel scheme.2. The dissertation proves that the group signature scheme based on Chinese remainder theorem presented by Chen ZW and his team can be breached by the attack from common modulus. Here an improvement scheme based on uncommon modulus is proposed, which is immune to common modulus attack with revocable property , unforgeability , coalition resistance and security against framing attack.Meanwhile, a novel group signature scheme which is immune to framing attack from the group center is also proposed by improving the generation algorithm of member secret keys and strengthening the mutual authentication between group members and the group center.3. The compensation scheme about the NTRU decryption failure presented by Yu WC and his team is proved false. Enlightened by the constructing principle of Chinese Remainder Theorem based on polynomial, the group signature scheme based on CRT and the design thought of NTRU-like signature algorithm, etc, a sort of novel group signature scheme which is based on NTRU and immune to all attacks for R-NSS and NTRUSign is presented.4. The secret key administration properties are analyzed in group signature. The generation algorithm of the secret sequences which satisfies the Strict Avalanche Criterion is put forward and analyzed by using the Strict Avalanche Criterion characteristic; furthermore, a key expansion algorithm based on DNA coding technology is designed and tested on randomization and Strict Avalanche Criterion characteristic. Moreover,some application technologies of the two secret sequence generation algorithms are dealt with in group signature.