In the original ElGamal signature scheme and it’s variants, two secret integers-private key and one-time secret key are required to produce a signature on a message, m. The private key of a system will be used throughout the life of the system whereas the one-time secret key only be used once and must be regenerated (different one-time secret key) when signing different message. This paper intr...

We argue the necessity of universally veriiable secret sharing for secrets as individual users' cryptographic keys, and propose protocols to realize such secret sharing for two most common public-key cryptosystems: discrete logarithm based and integer factorization based. The universal veriiabil-ity achieves sharing secret with multi third parties as shareholders using two-party protocols in wh...

Some chaos-based image encryption schemes using plain-images independent secret code streams have weak encryption security and are vulnerable to chosen plaintext and chosen cipher-text attacks. This paper proposed a two-level secret key image encryption scheme, where the first-level secret key is the private symmetric secret key, and the second-level secret key is derived from both the first-le...

A Key Distribution Center enables secure communications among groups of users in a network by providing common keys that can be used with a symmetric encryption algorithm to encrypt and decrypt messages the users wish to send to each other. A Distributed Key Distribution Center is a set of servers of a network that jointly realize a Key Distribution Center. In this paper we propose an unconditi...

Several unlinkable secret handshakes schemes have been proposed in recent years. As performing the successful secret handshakes is essentially equivalent to computing a common key between two interactive members of the same group. Therefore secret handshakes scheme is a key agreement protocol between two members of the same group. So it is necessary for a secret handshakes scheme to fulfill sec...

In order to hold secure electronic conference in Communication networks via insecure channels, a conference key distribution system should be constructed. The conference key distribution system (CKDS) is used for distributing a conference key shared among the participants of the conference and hence secure communications are achieved. In this paper, by using the secret sharing scheme based on t...

A semi-quantum key distribution (SQKD) protocol allows a quantum user and a limited “classical” user to establish a shared secret key secure against an allpowerful adversary. In this work, we present a new SQKD protocol where the quantum user is also limited in her measurement capabilities. We describe the protocol, prove its security, and show its noise tolerance is as high as “fully quantum” ...

We provide an analysis of the widely deployed SSH protocol’s key exchange mechanism. We exploit the design of the SSH key exchange to perform our analysis in a modular manner. First, a shared secret key is obtained via a Diffie-Hellman key exchange. Next, a transform is applied to obtain the application keys used by later stages of SSH. We define models, following well-established paradigms, th...

In wireless ad-hoc broadcast networks the pairing problem consists of establishing a (long-term) connection between two specific physical nodes in the network that do not yet know each other. We focus on the ephemeral version of this problem. Ephemeral pairings occur, for example, when electronic business cards are exchanged between two people that meet, or when one pays at a check-out using a ...

Group key transfer protocols depend on a mutually trusted key generation center (KGC) to transport the group key to all group members secretly. This approach requires that a trusted sever be set up, and it incurs communication overhead costs. In addition, the existing group key transfer protocols based on secret sharing all use threshold schemes that need to compute a -degree interpolating poly...