This paper provides an exposition of methods by which a trusted authority can distribute keys and/or broadcast a message over a network , so that each member of a privileged subset of users can compute a speciied key or decrypt the broadcast message. Moreover, this is done in such a way that no coalition is able to recover any information on a key or broadcast message they are not supposed to k...

The conference-key agreement protocol is a mechanism for generating a common session key among the authorized conference members. The common session key is used to encrypt communication messages transmitted over an open network. Inspired by traditional key agreement protocols and threshold cryptosystems, we have proposed a novel threshold conference-key agreement protocol in this paper. In the ...

identifier based cryptography, multiple trusted authority, pairings We investigate a number of issues related to a key generation service in identifier based cryptographic technology. In particular, we focus on how to make this service more trustworthy. Our solution is the use of multiple trusted authorities in identifier based cryptography (MTAIBC), where these trusted authorities work togethe...

Sometimes two parties who share a weak secret k such as a password wish to share a strong secret s such as a session key without revealing information about k to an active attacker. We assume that both parties can generate strong random numbers and forget secrets, and present three protocols for secure strong secret sharing, based on RSA, Diffie-Hellman, and El-Gamal. As well as being simpler a...

In the traditional scenario in cryptography there is one sender, one receiver and an active or passive eavesdropper who is an opponent. Depending from the application the sender or the receiver (or both) need to use a secret key. Often we are not dealing with an individual sender/receiver, but the sender/receiver is an organization. The goal of threshold cryptography is to present practical sch...

Anonymous communication is usually achieved by using overlay networks and public-key cryptography. Besides well-established protocols, based on onion routing, various competing solutions have been proposed in the literature. In this work we extend the Crowds system by providing sender and adjustable receiver anonymity. Our solution is robust against a coalition of passive adversaries having int...

Identity-Based cryptography has been proposed in mobile ad-hoc networks (MANETs) to provide security. However, the figure of the Private Key Generator (PKG) is not adequate in the MANET setting, since it may not be reachable by all nodes, can fail during the life-time of the protocol or can even be attacked, compromising the whole system. Previous works distribute the task of the PKG among a se...

The basic idea in secret sharing is to divide the secret key into pieces, also called as ‘shares’ and distribute the pieces to different persons so that certain subsets of the persons can get together to recover the key. In the outline of threshold schemes, we wanted k out of n participants to be able to determine the key. In practice, it is often needed that only certain specified subsets of t...

One of the basic problems in cryptography is the generation of a common secret key between two parties, for instance in order to communicate privately. In this paper we consider information-theoretically secure key agreement. Wyner and subsequently Csiszár and Körner described and analyzed settings for secret-key agreement based on noisy communication channels. Maurer as well as Ahlswede and Cs...

When sensor networks deployed in unattended and hostile environments, for securing communication between sensors, secret keys must be established between them. Many key establishment schemes have been proposed for large scale sensor networks. In these schemes, each sensor shares a secret key with its neighbors via preinstalled keys. But it may occur that two end nodes which do not share a key w...