In order to ensure authenticity of the information for conference key negotiation, the information which each party sends should be authenticated. Digital signature and share secret are two methods for authentication. Identity-based public key cryptosystems from the Weil pairing on elliptic curve are introduced. Two authenticated conference key agreement protocols are designed using identitybased signature scheme and identity-based Diffie-Hellman shared key. The protocols are secure and efficient. They can be applied to all kinds of environment in which multi-parties negotiate session keys.
In order to ensure authenticity of the information for conference key negotiation, the information which each party sends should be authenticated. Digital signature and share secret are two methods for authentication. Identity-based public key cryptosystems from the Weil pairing on elliptic curve are introduced. Two authenticated conference key agreement protocols are designed using identitybased signature scheme and identity-based Diffie-Hellman shared key. The protocols are secure and efficient. They can be applied to all kinds of environment in which multi-parties negotiate session keys.
Through the group key agreement, all group members could negotiate a common session key which is used in later secure communication.While simple GKA cannot provide enough security to resist the adversary's attack, and the malicious damage during the agreement makes the authenticated key agreement particularly important.In identity-based authentication, user's unique identity information is used as the public key, which makes it exempt from a series of management of the certification in public-key infrastructure.Thereby, the identity-based key agreement can simplify the key management procedures and reduce the risk of failure at the certification authority.Recently, several identity-based group key agreement protocols have been proposed, however most of them are either vulnerable to impersonation and replay attack or inefficient and unscalable.This paper proposes a novel authenticated group key agreement protocol which is based on bilinear pairings.It needs two rounds to negotiate the session key, and the low computational complexity makes the protocol efficient and scalable.Meanwhile, our protocol also ensures the forward and backward secrecy and the key independence.Under the Decisional Diffie-Hellman assumption, our protocol is proved to be secure against the adversary. 1.
Abstract. In identity-based public-key cryptography, an entity’s public key can be easily derived from its identity. The direct derivation of public keys in identity-based public-key cryptography eliminates the need for certificates and solves certain public key management problems in traditional public-key cryptosystems. Recently, the notion of asymmetric group key agreement was introduced, in which the group members merely negotiate a common encryption key which is accessible to any entity, but they hold respective secret decryption keys. In this paper, we first propose a security model for identity-based authenticated asymmetric group key agreement (IB-AAGKA) protocols. We then propose an IB-AAGKA protocol which is proven secure under the Bilinear Diffie-Hellman Exponent assumption. Our protocol is also efficient, and readily adaptable to provide broadcast encryption.
In this paper, we present a new efficient authenticated key agreement protocol. Compared with other cross-domain protocols which are all in the same cryptosystem, our protocol is innovatively designed to shift between the Public Key Infrastructure (PKI) and the Identity-based Cryptosystem (IBC). This protocol combined with heterogeneous signcryption method is proved to satisfy confidentiality and unforgeability on the basis of the assumptions of Computational Diffie-Hellman problem (CDHP) and Bilinear Diffie-Hellman problem (BDHP) in the authentication phases, and it simultaneously guarantees the ciphertext anonymity. In addition, it can efficiently resist kinds of active attacks such as known-session key attack, key forge attack, and known-temporary secret key attack. Compared with other two-party authenticated key agreement protocols, the newly proposed key agreement protocol has better security, practicability and efficiency.
Authenticated key agreement protocol is designed to provide pair of parties communicating over an insecure network with a secure session key.However,most of the existing authenticated key agreement protocols are not designed for protecting privacy.We emphasize user's privacy properties in network services,in particular we stress anonymity and deniability.We specify the desired security properties of privacy-enhancing authentication key agreement protocols,i.e.mutual authentication,key control,key confirmation,session-key confidentiality,known-key security,forward secrecy,anonymity of user,forward anonymity of user,unlinkability,deniability.Based on elliptic curve cryptosystem we also propose a protocol which satisfies all the desired security properties.
Key agreement and digital signature are two significant and most useful contributions of modern cryptography. Such protocols and schemes allow two or more parties to establish a common session key securely in the presence of a malicious adversary and provide means of ensuring data origin authentication, data integrity and non-repudiation. Thus, secure key agreement protocols and signature schemes are fundamental building blocks for constructing complex higher-level protocols.
In this thesis, we deal with security analysis of existing key agreement protocols and digital signature schemes. We examine ten authenticated key agreement protocols without key confirmation, out of which half are two-party and the other half are three-party, and one deterministic identity-based aggregate signature scheme. By giving concrete attacks, we show that these protocols and the scheme do not possess the desirable security attributes or security attributes claimed by their authors. We also present a secure deterministic identity-based signature scheme that supports partial aggregation.
First, we show that Okamoto's and Chen et al.’s protocol cannot withstand the key-compromise impersonation attack and that Tan et al.’s, Lim et al.’s and two protocols of Holbl et al. are insecure against the impersonation attack and the man-in-the-middle attack. Next, we prove that one protocol of Holbl et al. is vulnerable to the insider attack, one to the unknown key-share attack, one protocol allows an adversary to compute the private key of any user and one protocol allows her to compute the shared session key. We also show that Selvi et. al.'s deterministic identity-based aggregate signature scheme is universally forgeable, i.e., anyone is able to easily generate valid signatures on any messages of his choice having on average twelve genuine digital signatures.
In the end, we introduce a new deterministic identity-based signature scheme and formally prove its security in the random oracle model. The scheme is a major improvement of the signature scheme proposed by Selvi et. al. and offers the same tight security reduction to the underlying gap Diffie-Hellman problem. Because the newly proposed scheme is deterministic it allows partial aggregation, i.e., all the signatures from the same signer can be aggregated into one single short signature.
In this paper, the tripartite identity-based key agreement is investigated. Inspired by designated verifier signature schemes, a tripartite identity-based key agreement protocol with explicit authentication is proposed with the good authentication of signatures. The new protocol can achieve remarkable security properties, such as perfect forward secrecy and unknown key share. More theoretically, the security proving of the protocol is given in the random oracle model under the Bilinear Diffie-Hellman assumption. The efficiency of the protocol is lying on that three parties can establish an agreed session key after only one round of message exchange. Detailed efficiency analysis compared with other protocols is also made.