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Although the objective of secure communication can be achieved by using cryptographic tools, the undeniability that results from cryptographic properties may create a potential threat to the sender of the message. Unfortunately, most existing deniable protocols only provide 1-out-of-2 deniability. When both parties (the sender and the receiver) are allowed to deny generating the message, a dispute might occur between these two parties. The 1-out-of-2 deniable protocol can result in an unfair resolution of the dispute. Therefore, we propose a new model of deniability, called 1-out-of-∞ deniability, that can provide full deniability. The 1-out-of-∞ deniability protocol allows the originator of the message to deny that he or she generated the message, since there are an infinite number of possible message generators; at the same time, all transmitted messages can be protected and authenticated between the sender and the intended receiver. Our design can be implemented by using any public-key cryptography technique. We also analyze the correctness of the proposed protocols based on logical rules, and two practical examples are given to illustrate our design. [ABSTRACT FROM AUTHOR]

Abstract: In 2008, Lee et al. proposed two multiple-key agreement protocols, first one based on elliptic curve cryptography (ECC) and the other one, based on bilinear pairings. Shortly after publication, Vo et al. showed that the Lee–Wu–Wang’s pairing-based protocol is vulnerable to impersonation attack then for removing the problem, they proposed an improved protocol. In this paper, first We show that the Lee–Wu–Wang’s ECC-based protocol is insecure against forgery attack and also, if long-term private keys of two entities and one key of the session keys are revealed, the other session keys are exposed too. Then, we demonstrate that the Vo–Lee–Yeun–Kim’s protocol is vulnerable to another kind of forgery attacks and a reflection attack. [Copyright &y& Elsevier]

Abstract: In this paper, we present a strongly secure identity-based (ID-based) two-party authenticated key agreement (AKA) protocol, which captures all basic desirable security properties including master key forward secrecy, ephemeral secrets reveal resistance and so on, and is provably secure in the extended Canetti–Krawczyk (eCK) model. The security of the protocol can be reduced to the standard Computational Bilinear Diffie–Hellman assumption in the random oracle model. Our scheme is secure as long as each party has at least one uncompromised secret. Also, we give a strongly secure variant of the protocol. The variant has a much lower computational overhead than the original scheme, while its security relies on the Gap Bilinear Diffie–Hellman assumption. Currently, there are few ID-based AKA protocols that are provably secure in the strong eCK model. Compared with previous ID-based AKA schemes, our protocols have advantages over them in security or efficiency. [Copyright &y& Elsevier]

Peer-to-peer (P2P) networks are vulnerable to peers who cheat, propagate malicious code, leech on the network, or simply do not cooperate. The traditional security techniques developed for the centralized distributed systems like client-server networks are insufficient for P2P networks by the virtue of their centralized nature. The absence of a central authority in a P2P network poses unique challenges for reputation management in the network. These challenges include identity management of the peers, secure reputation data management, Sybil attacks, and above all, availability of reputation data. In this paper, we present a cryptographic protocol for ensuring secure and timely availability of the reputation data of a peer to other peers at extremely low costs. The past behavior of the peer is encapsulated in its digital reputation, and is subsequently used to predict its future actions. As a result, a peer's reputation motivates it to cooperate and desist from malicious activities. The cryptographic protocol is coupled with self-certification and cryptographic mechanisms for identity management and countering Sybil attack. We illustrate the security and the efficiency of the system analytically and by means of simulations in a completely decentralized Gnutella-like P2P network. [ABSTRACT FROM AUTHOR]

Mobile Ad-hoc NETworks (MANETs) are expected to play an important role in tactical military networks by providing infrastructureless communication. However, maintaining secure and instant information sharing is a difficult task especially for highly dynamic military MANETs. To address this requirement, we propose a new multi-tier adaptive military MANET security protocol using hybrid cryptography and signcryption. In our protocol, we bring novelties to secure military MANET communication for three main points: Cryptographic methods used in MANETs, hybrid key management protocols and structural organization of the military MANETs. As a new approach, we use hybrid cryptography mechanisms and Elliptic Curve Pintsov-Vanstone Signature Scheme (ECPVS8) that provide security and performance advantages when compared to some traditional cryptographic methods. Furthermore, multi-leveled security approach of our protocol provides adaptive solutions according to the requirements of different military units in the MANET. We also use a hybrid key management technique that combines the benefits of both decentralized protocols with single point of failure resistivity and centralized protocols with low rekeying cost. Last, the proposed network structure facilitates certification and key management for the MANET by providing flexibility for Mobile Backbone Network (MBN) tiers. [ABSTRACT FROM AUTHOR]

Abstract: We show how cryptographic protocols using Diffie–Hellman primitives, i.e., modular exponentiation on a fixed generator, can be encoded in Horn clauses modulo associativity and commutativity. In order to obtain a sufficient criterion of security, we design a complete (but not sound in general) resolution procedure for a class of flattened clauses modulo simple equational theories, including associativity–commutativity. We report on a practical implementation of this algorithm in the MOP modular platform for automated proving; in particular, we obtain the first fully automated proof of security of the IKA.1 initial key agreement protocol in the so-called pure eavesdropper model. [Copyright &y& Elsevier]

Non‐interference has been advocated by various authors as a uniform framework for the formal specification of security properties in cryptographic protocols. Unfortunately, specifications based on non‐interference are often non‐effective, as they require protocol analyses in the presence of all possible intruders. This paper develops new characterizations of non‐interference that rely on a finitary representation of intruders. These characterizations draw on equivalence relations built on top of labelled transition systems in which the presence of intruders is accounted for, indirectly, in terms of their (the intruders') knowledge of the protocols' initial data. The new characterizations apply uniformly to trace and bisimulation non‐interference, yielding proof techniques for the analysis of various security properties. We demonstrate the effectiveness of such techniques in the analysis of different properties of a fair exchange protocol. [ABSTRACT FROM AUTHOR]

Abstract: The APSSNMP network management protocol was proposed as a secure alternative to the Simple Network Management Protocol (SNMP) used in the TCP/IP suite. The designers claimed that it resists meet-in-the-middle (MITM) attacks. In this paper, we present an advanced MITM attack on the APSSNMP and hence show that it fails to achieve its design objective of providing better security against MITM attacks. Since the APSSNMP has been presented in several journals, and IEEE and IASTED conferences, our result is important to highlight to network implementers and users of distributed systems that the APSSNMP is not secure for practical deployment. [Copyright &y& Elsevier]