Modular Security Proofs for Key Agreement Protocols

S WANG, Zhenfu Cao, Kim‐Kwang Raymond Choo +1 more

Shengbao Wang, Zhenfu Cao, Zhaohui Cheng +1 more

Abstract. There are several essential features in key agreement protocols such as key escrow (essential when confidentiality, audit trail and legal interception are required) and perfect forward secrecy (i.e., the security of a session key established between two or more entities is guaranteed even when the private keys of the entities are compromised). Majority of the existing escrowable identity-based key agreement protocols, however, only provide partial forward secrecy. Therefore, such protocols are unsuitable for real-word applications that require a stronger sense of forward secrecy — perfect forward secrecy. In this paper, we propose an efficient perfect forward secure identity-based key agreement protocol in the escrow mode. We prove the security of our protocol in the random oracle model, assuming the intractability of the Gap Bilinear Diffie-Hellman (GBDH) problem. Security proofs are invaluable tools in assuring protocol implementers about the security properties of protocols. We note, however, that many existing security proofs of previously published identity-based protocols entail lengthy and complicated mathematical proofs. In this paper, our proof adopts a modular approach and, hence, simpler to follow.

Soohyun Oh, Jin Kwak, Seungwoo Lee +1 more

Yafei Wang

Most Identity-based Authenticated Key Agreement(ID-AKA) protocols have poor performance on security and the efficiency.To solve this problem,this paper presents an improved ID-AKA protocol.Security proof with the modular approach in the mBR model is provided,which means the new protocol satisfies perfect forward security,PKG forward security,resistant to key-compromise impersonation.Furthermore,the new protocol can satisfy resistance to leakage of ephemeral secrets.Compared with previous ID-AKA protocols which can satisfy the same security properties,the new protocol has higher efficiency.

Simon Blake-Wilson⋆⋆, Don B. Johnson, Alfred Menezes

Manman Geng, Futai Zhang

Key agreement is one of the fundamental cryptographic primitives in public key cryptography. So far several certificateless two-party authenticated key agreement (CL-T-AKA) protocols have been proposed. However, all these protocols are based on bilinear map and most of them are without formal security proof. In this paper, we present a new formal security model of CL-T-AKA protocols and bring forward the first two-party key agreement protocol without the computation of expensive bilinear map. Our protocol is secure under the security model assuming the Gap-DH problem is intractable. With respect to efficiency, our protocol requires a single round of communication in which each party sends only one group element, and needs only five modular exponentiation computations. In addition, we point out that an existing certificateless two-party key agreement protocol cannot resist man-in-the-middle attack.