Abstract-In mobile ad hoc networks, due to unreliable wireless media, host mobility and lack of infrastructure, providing secure communications is a big challenge in this unique network environment. Usually cryptography techniques are used for secure communications in wired and wireless networks. The asymmetric cryptography is widely used because of its versatileness (authentication, integrity, and confidentiality) and simplicity for key distribution. However, this approach relies on a centralized framework of public key infrastructure (PKI). The symmetric approach has computation efficiency, yet it suffers from potential attacks on key agreement or key distribution. In fact, any cryptographic means is ineffective if the key management is weak. Key management is a central aspect for security in mobile ad hoc networks. In mobile ad hoc networks, the computational load and complexity for key management is strongly subject to restriction of the node's available resources and the dynamic nature of network topology. In this paper, we propose a secure and efficient key management framework (SEKM) for mobile ad hoc networks. SEKM builds PKI by applying a secret sharing scheme and an underlying multicast server group. In SEKM, the server group creates a view of the certification authority (CA) and provides certificate update service for all nodes, including the servers themselves. A ticket scheme is introduced for efficient certificate service. In addition, an efficient server group updating scheme is proposed.
We present a new approach to designing public-key cryptosystems based on covers and logarithmic signatures of non-abelian finite groups. Initially, we describe a generic version of the system for a large class of groups. We then propose a class of 2-groups and argue heuristically about the system's security. The system is scalable, and the proposed underlying group, represented as a matrix group, affords significant space and time efficiency.
A recently proposed Chaotic-Key Based Algorithm (CKBA) has been shown to be unavoidably susceptible to chosen/known-plaintext attacks and ciphertext-only attacks. In this paper we enhance the CKBA algorithm three-fold: 1) we change the 1-D chaotic Logistic map to a piecewise linear chaotic map (PWLCM) to improve the balance property, 2) we increase the key size to 128 bits, and 3) we add two more cryptographic primitives and extend the scheme to operate on multiple rounds so that the chosen/knownplaintext attacks are no longer possible. The new cipher has much stronger security and its performance characteristics remain very good.
Abstract. In the late 1970s Magliveras invented a private-key cryptographic system called Permutation Group Mappings (PGM). PGM is based on the prolific existence of certain kinds of factorization sets, called logarithmic signatures, for finite permutation groups. PGM is an endomorphic system with message space ~1 for a given finite permutation group G. In this paper we prove several algebraic properties of PGM. We show that the set of PGM transformations ~q'o is not closed under functional composition and hence not a group. This set is 2-transitive on Elo I if the underlying group G is not hamiltonian and not abelian. Moreover, if the order of G is not a power of 2, then the set of transformations contains an odd permutation. An important consequence of these results is that the group generated by the set of transformations is nearly always the symmetric group ~. Thus, allowing multiple encryption, any permutation of the message space is attainable. This property is one of the strongest security conditions that can be offered by a private-key encryption system.
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