Research On Confirmer Digital Signatures

Digital signatures, one of the most important components of cryptography, are the basic theory for protecting the integrity and authenticity of information. With various application backgrounds in electronic commence, a research on digital signatures having different features is not only necessary but also important. Both confirmer signatures and key insulated signatures are studied in this paper and the main work are as follows:Firstly, the overview of confirmer signatures is presented and the protocols, arithmetics as well as security definitions in different formal confirmer signatures models are analyzed respectively. Secondly, the generic constructions based on different models for designing secure and efficient confirmer signatures are analyzed. Finally, A new threshold and confirmer signature scheme for group or organization is proposed by using the multiplicative secret sharing and RSA public key cryptosystem, whose confirming and denying protocols are constructed by using the idea of zero-knowledge proof. The new scheme can be applied to justice-subscribe of electronic contract.The key-insulated signatures and public-key cryptosystems whose core ideais key-evolution mechanism are studied. Both systems are used to decrease the damages due to the compromise of secret key. A new strong (t, N)-key-insulated public-key encryption scheme based on the CDH assumption is proposed according to the (t, N)-key-insulated public-key encryption model and security definition presented by Yevgeniy-Jonathan-Moti. The new scheme has been proved against chosen-cipertext attack in random oracle.