Research On Identity-based Signature And Multi-signcryption

Traditional public key cryptography highly depends on certificate authority. The owner of public key needs to make the public key match the identity information in the certificate authority, and the sender authenticate the publisher through certificate authority before using the public key, but the computing power and memory property certificate authority faces a huge test, center system is so high at work. For this purpose, Shamir proposes identity-based cryptography, the main idea is based on the user’s identity information as a public key, so the management of public key and identity information is simplified, and private key generator which is recognized reliable generates the private key and sends to user safely. The private key generator is only responsible for generating the corresponding private key, the management of public key and identity information is in addition to responsibility.Based on researching identity-based cryptography, deep analysis of the problems which is identity based encryption, strong designated verifier signature, undeniable signature, undeniable signature and signcryption multi-signcryption is carried on, and the corresponding algorithm is analyzed and improved from the safety and efficiency. In terms of research ideas, firstly improve the delegatability of strong designated verifier signature and carry on theoretical proof and data analysis through security proof and efficiency analysis. Then improve the efficiency of identity-based multi-signcryption in the standard model, optimize the performance of the algorithm based on ensuring the security of the algorithm, so the calculation of consumption of the system is reduced, fully reflect the necessary of balancing security and efficiency of algorithms.The main contributions are as follows.1. The paper presents a thorough study of identity-based cryptography and classic identity-based strong designated verifier signature, find the defect of some schemes and the problem of efficiency. Faced with these problems, a new efficient identity-based strong de-signated verifier signature scheme is proposed. Through corresponding security proof and efficiency analysis, the results show that the new scheme could satisfy the security require-ments of non-transferability, unforgetability, non-delegatability and the new scheme is more efficient.2. Through studying identity-based signcryption, find the unsafety of most schemes in the random oracle model and cost a large amount of calculation. At the same time, to adapt multi-signers settings, proposes an efficient and secure identity-based multi-signcryption scheme, then prove secure against adaptive chosen ciphertext attacks and adaptive chosen message attacks under decisional bilinear Diffie-Hellman assumption. Compared with the known schemes, the scheme enjoys shorter multi-signature length and less operation.