Study On The Sanitizable Digital Signature Scheme

Digital signature is an integral part of the Internet security processing technology, it isable to provide integrity, authentication and non-repudiation of information. It is an importantpart of public-key cryptosystem. Sanitizable digital signature, a special kind of digitalsignature, allows a semi-trusted sanitizer (or reviewer) to revise certain part of the originalinformation without interacting with the original signers and at the same time guarantees apublic verification of the revised information. Sanitizable digital signature deals with issuesabout how to conceal sensitive information in the process of the signature and therefore iswidely used in security issues of private files in government or military department and otherissues like the medical privacy data publishing and secure routing.Identity-Based Public Key Cryptography solved the problems which are prevalent intraditional public key cryptography, such as excessive use of resources and difficulty inmanagement of certificate preservation, revocation, releasing and verification. Standardmodel enables to deal with issues that can not be realized or constructed by the random oraclemodel, which takes the hash function as an ideal model.The thesis will focus on a systematic study on the cipher system and provable safety ofidentity-based sanitizable signature scheme in the standard model, It specifically contains:(1) Under the use of bilinear pairings, based on Waters signature and Li signature, anefficient provably secure identity-based sanitizable signature scheme in standard model isproposed. Firstly, given the identity-based purification signed formal definition and securitymodel of identity-based sanitizable signature and then a specific build, lastly to prove thesecurity of the scheme in the standard model based on the computational Diffie-Hellmanassumption. The analysis shows that the proposed scheme is able to meet the unforgeability,non-discriminative and immutability. And compared to the existing schemes, the bilinearpairings pre-op reduces the operation program in computing and index computation, improvesefficiency.(2) Combined with the idea of sanitizable signature and proxy signature, and based onthe Waters signature technology, an identity-based sanitizable proxy signature scheme in a standard model is proposed. Firstly, given formal definition and security model of sanitizableproxy signature, and then gives the specific build, and finally prove the security of the schemein the standard model based on the computational Diffie-Hellman assumption. Securityanalysis shows that the proposed scheme satisfies security requirements of the identity-basedsanitizable proxy signature, and is of strong practical value.