In this paper we propose a very efficient two-round k-out-of-n oblivious transfer scheme, in which R sends O(k) messages to S, and S sends O(n) messages back to R. The computation cost of R and S is reasonable as R needs O(k) operations and S needs O(n) operations. The choices of R are unconditionally secure and the secrecy of unchosen messages is guaranteed as well if the decisional bilinear D...

We consider a key exchange procedure whose security is based on the difficulty of computing discrete logarithms in a group, and where exponentiation is hidden by a conjugation. We give a platform-dependent cryptanalysis of this protocol. Finally, to take full advantage of this procedure, we propose a group of matrices over a noncommutative ring as platform group.

A shared secret, conference key, must be established among members to securely communicate among them. The Diffie-Hellman is often used for the conference key establishment. In a heterogenous network, the participants have different resources. Therefore, different burden should be placed on different participants. However, most protocols did not address this problem. Wade Trappe et. al. address...

We propose a new class of key establishment schemes which are based on geometric generalizations of the classical Diffie-Hellman. The simplest of our schemes – based on the geometry of the unit circle – uses only multiplication of rational numbers by integers and addition of rational numbers in its key creation. Its first computer implementation works significantly faster than all known impleme...

The multiparty key exchange introduced in Steiner et al. and presented in more general form by the authors is known to be secure against passive attacks. In this paper, an active attack is presented assuming malicious control of the communications of the last two users for the duration of only the key exchange.

A fundamental building block of secure group communication is the establishment of a common group key. This can be divided into key agreement and key distribution. Common group key agreement protocols are based on the Diffie-Hellman (DH) key exchange and extend it to groups. Group key distribution protocols are centralized approaches which make use of one or more special key servers. In contras...

This paper studies the relationships between the traditional Diffie-Hellman key agreement protocol and the identity-based (ID-based) key agreement protocol from pairings. For the Sakai-Ohgishi-Kasahara (SOK) ID-based key construction, we show that identical to the Diffie-Hellman protocol, the SOK key agreement protocol also has three variants, namely ephemeral, semi-static and static versions. ...

This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Abstract This memo describes a key-exchange method for the Se...

Deniable authentication is a new protocol which not only enables a receiver to identify the source of a received message but also prevents a third party from identifying the source of the message. The proposed protocol in this paper makes use of bilinear pairings over elliptic curves, as well as the Diffie-Hellman key exchange protocol. Besides the security properties shared with previous authe...

The Weil and Tate pairings are a popular new gadget in cryptography and have found many applications, including identity-based cryptography. In particular, the pairings have been used for key exchange protocols. This paper studies the bit security of keys obtained using protocols based on pairings (that is, we show that obtaining certain bits of the common key is as hard as computing the entire...