Research On Two-Party Authenticated Key Agreement Protocols In Identity And Certificateless Based Public Key Cryptography

Security issues are key problems for the popularization and application of network technology. Cryptographic theory and techniques provide assurance for data transmission. Authenticated key agreement (AKA) protocol is a process whereby two or multi-parties exchange messages, authenticate each others and establish shared session keys for later secure communications in the public network environment. As one of the core elements of cryptography and network security, it is of great academic significance to study the design and security analysis of AKA protocol, as well as of pervasive and practical backgrounds in the secure network applications by integrating with communication technologies. However, the related research in the past years shows that it is not a trivial work for its complexity. In this thesis, we focus on the study of the two-party identity-based and certificateless-based AKA protocols, ranging from the establishment of security models, attacks to some of the published protocols, up to the design of new schemes and proofs.Security models based on computational complexity provide great support to the assurance of the security and efficiency for the AKA protocols. Proving security procedure under the proper security model gives the convincing evidence for trusting the protocols. Solution of proving security means such a process-Firstly the specification of the security model is provided and proper adversarial powers were described in such a model, and then the formal security definition of the protocol goals was figured out, a proof is laid out to clarify that the protocol meets its goals within such a model by stating the proper assumptions related to the computational complexity. The specification of the security model has direct bearing on the attack types which were covered, so it reflects the strength of the security model. With the emergence of certificateless-based cryptographic theory and certificateless-based AKA protocols, the research of security models in the certificateless settings is becoming an important issue. In this thesis, we investigated notions of various security models respect to the adversarial powers. Especially, a modified security model for the certificateless-based AKA protocol was presented.Some necessary security attributes should be satisfied by the AKA protocols, such as known session-key secrecy, unknown key-sharing secrecy, key-compromised impersonation secrecy, forward secrecy, know session-specific information secrecy etc. Various attacks require the proposed protocol should satisfy more rigorous security requirements. Identity-based cryptography and bilinear mapping (paring) function are key techniques to design AKA protocols. Some design ideas can be borrowed from the identity-based encryption schemes to construct efficient identity-based AKA protocols. Generally, identity-base encryption schemes adopt the plaintext-blinding technique by embedding randomness. The proper decrypter can recover the plaintext from the ciphertext after acquiring the random elements. Constructing identity-based AKA protocols with such idea will greatly reduce the computational costs and improve the efficiency of schemes compared to using encryption and signature scheme directly. In this thesis, several identity-based AKA protocols published recently were critically examined. It is found that they exhibit vulnerabilities of varying severity, such as the key-replicating attack, the key-compromised impersonation attack, and the known session-specific information attack etc. Several secure and efficient AKA schemes based on encryption schemes were proposed, which can be used in the key-escrow mode and the key-escrowless mode.Certificateless public key cryptography proposes a new paradigm which lies between in the identity-based public key cryptography and the traditional public key cryptography. It is regarded as the combination of these two ones. So far, the published AKA protocols in the literature are few in number, almost all of them are absence of formal security proof, as well as vulnerable to some types of attack. In this thesis, several published certificateless-based AKA protocols were analyzed to be vulnerable to several types of attack; Then a serial of certificateless-based AKA protocols were proposed based on some certificateless-based encryption schemes.The main contributions are summarized as below:1. An improved security model related to certificateless-based AKA protocol was proposed by strengthening the power of the adversary for querying intermediate secrets forming from all the local secret keys. Meanwhile, detailed analysis and comparisons were given to the classical security models in the literature.2. New identity-based schemes with stronger security were proposed in the key-escrowless and key-escrow mode. Security proof in the standard model of one scheme with key-escrow and perfect forward secure secrecy was given. Thus solves one open question posed by Wang et al.3. Different security attacks were demonstrated to some published certificateless-based two-party AKA schemes; A series of new schemes were proposed inspired on the certificateless-based encryption schemes. Analysis shows that they all meet the necessary security attributes. One of them captures the security requirements of the strongest security model at present, while it achieves better computational efficiency.