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...

Design a Secure Authenticated Key Exchange (AKE) protocol is a wide research area. Many works have been done in this field and remain few open problems. Design an AKE-secure without NAXOS approach is remaining as an open problem. NAXOS approach [18] is used to hide the ephemeral secret key from an adversary even if the adversary in somehow may obtain the ephemeral secret key. Using NAXOS approa...

Group key establishment is an important mechanism to construct a common session key for group communications. Conventional group key establishment protocols use an on-line trusted key generation center (KGC) to transfer the group key for each participant in each session. However, this approach requires that a trusted server be set up, and it incurs communication overhead costs. In this article,...

A profiling adversary is an adversary which aims to classify messages into pre-defined profiles and thus gain useful information regarding the sender or receiver of such messages. Usual chosen-plaintext secure encryption schemes are capable of securing information from profilers, but these schemes provide more security than required for this purpose. In this paper we study the requirements for ...

83.2 Key Management Myths .................................................... 1070 Myth 1: A Key Qualifies as “Randomly Generated” If One or More Persons Create the Key Components from Their Imagination † Myth 2: An “Authorized” Person Can Create or Enter Cryptographic Keys without Compromising a Key † Myth 3: Requiring a Second Person to Supervise or Observe the Key Entry Process Is Dual Cont...

Until now no distributed discrete-logarithm key generation (DKG) protocol is known to be universally composable. We extend Feldman’s verifiable secret sharing scheme to construct such a protocol. Our result holds for static adversaries corrupting a minority of the parties under the Decision Diffie-Hellman assumption in a weak common random string model in which the simulator does not choose the...

Among the various computer security techniques practice today, cryptography has been identified as one of the most important solutions in the integrated digital security system. Cryptographic techniques such as encryption can provide very long passwords that are not required to be remembered but are in turn protected by simple password, hence defecting their purpose. In this paper, we proposed ...

By adopting a non-interactive information-theoretic secure verifiable secret sharing scheme in an unorthodox way, a verifiable fingerprint vault scheme is presented in this paper. Fuzzy vault scheme is a novel cryptographic construct which can increase the security of the biometric template in a biometric authentication system. It can be also used to bind the cryptographic key and the user in a...

Security is an increasingly important attribute for multimedia applications that require prevention of unauthorized access to copyrighted data. Two approaches have been used to protect scalable video content in distribution: Partial encryption and progressive encryption. Partial encryption provides protection for only selected portions of the video. Progressive encryption allows transcoding wit...