Study On Content Extraction Signature System

Information security is one of the most important problems in modern information society and becomes a new important subject in the information science. Digital signature, which can provide authentication, integrity and non-repudiation, is one of the key techniques of information security and plays a very important role in E-commerce and E-governance. As the deepening of digital signature research and the rapid development of E-commerce and E-governance, the standard cryptology system can not still meet the need in practice, thus need to study more convenient, faster and more efficiently cryptology system.Content Extraction Signature is a new digital signature system. It enables the user to extract selectively verifiable content from signed document and is unnecessary for the user to contact with the signer. We compare Content Extraction Signature with standard digital signature, and analyze the applied advantage of Content Extraction Signatures in E-commerce and E-governance. Based on the Bilinear Pairings, combine Identity-based Cryptography and Group Signature, an ID-based Content Extraction Group Signature is proposed. It enables the user to extract signature efficiently and is unnecessary for the user to contact with the signer, and analyzes its efficiency and security.In threshold Signature system, several users share the private key with threshold mode and can cooperate with each other to generate a valid group signature. It could enhance security of the system and solve the problem of high concentrated rights. An ID-based Content Extraction threshold Signature based on the Bilinear Pairing is proposed. Effective threshold signature generation and signature extraction of the proposed signature scheme can be realized without more interaction with the signer. The proposed signature scheme ensures efficiency and robustness, and is showed secure against existential forgeable on adaptively chosen message and ID attack in the random oracle model.As compared with standard public key cryptosystems, self-certified public key system does not need public key certificate, a verifier can verify both certificate and signature together. So it reduces the space storage and computational efforts, and saves communication costs. Based on the Discrete Logarithm problem, combine Self-certified public key and Content Extraction Signature, a Self-certified Content Extraction Signature is proposed, and analyzes its security.