Study On Signcryption Schemes Based On Self-certified Cryptography

In the self-certified cryptography, the user generates his own public key, the certificate authority calculates the partial private key of the user, then the user utilizes the partial private key to generate his own private key, so the inherent key escrow problem is overcome in identity-based signature schemes; a verifier can verify the validity of the signature and the authenticity of public key simultaneously in a single step; no certificate is required for verifying the authenticity of the public key.Signcryption can perform digital signature and encryption simultaneously in a reasonable logical single step; its computational costs and communication overheads are lower than the traditional signature-then-encryption approach. Signcryption provides a good approach to transmit messages when both confidentiality and authenticity are needed. Signcryption schemes with special properties may be constructed by applying the concept of self-certified public key to signcryption which has some peculiar characteristics.In this dissertation, we merge the technology of self-certified public key and signcryption, and study the construction and the provable security of the signcryption schemes based on self-certified cryptography. It includes the following four aspects.1. A new efficient signcryption scheme is proposed. We first give the formal model and then describe the proposed scheme. Finally, we prove its security in the random oracle model and analyze the performance. It is showed that our scheme is more efficient than existing schemes in terms of security and performance.2. We propose a self-certified proxy signcryption scheme by appling the concept of self-certified public key to proxy signcryption and prove its security in random oracle model. Performance analysis shows that our scheme is more efficient than the previously proposed scheme.3. Merging the concept of self-certified public key and blind signcryption, We propose a self-certified blind signcryption scheme. we prove its security in the random oracle model and analyze its performance. Analysis shows that the efficiency of our scheme is higher than the previously proposed scheme.4. We propose a multi-recipient signcryption scheme based on self-certified crytography by combining the thought of self-certified cryptography and multi-signcryption. We first describe the proposed scheme, then prove its security and analyze its performance. It is showed that our scheme is useful to broadcast a message to multiple users in a secure and authenticated manner.