Commutative encryption is a useful but rather strict notion in cryptography. In this paper, we define a loose variation of commutative encryption-commutative-like encryption and give an example: the generalization of ElGamal scheme. The application of the new variation is also discussed.

A critique of the proposed encryption scheme based on the DLP γ = αβ is provided. It is described how a plaintext can be obtained from a valid ciphertext by computing a single traditional discrete logarithm in a cyclic group. Furthermore, it is shown that the proposed encryption scheme is in fact equivalent to the ElGamal encryption scheme.

In this work, a new digital signature based on elliptic curves is presented. We established its efficiency and security. The method, derived from a variant of ElGamal signature scheme, can be seen as a secure alternative protocol if known systems are completely broken.

| This paper presents a group-oriented (t;n) threshold cryptosystem in which the sender determines the threshold parameter t and selects the group of intended receivers. The proposed scheme is practical, eecient and non-interactive. It does not need any trusted clerks or trusted key distribution centers. The security of the scheme is equivalent to the security of the original ElGamal cryptosystem.

We consider the general relay channel. For this setup, the best achievability result was derived by Cover and ElGamal, in theorem 6 of their paper from 1979. In this work we apply simultaneous decoding of both source and relay messages at the receiver and obtain a set of rates that contains those of Cover and El-Gamal.

The concept of Semigroup Action Problem (SAP) was introduced by C. Monico in 2002. He defined Diffie-Hellman key exchange and ElGamal cryptosystem taking SAP as an underlying problem. The aim of this paper is to define the application of SAP in designing a zero knowledge undeniable signature scheme. We also discuss the security analysis of the proposed scheme.

In this paper, we investigate how threshold cryptography can be conducted with the Asmuth-Bloom secret sharing scheme and present three novel function sharing schemes for RSA, ElGamal and Paillier cryptosystems. To the best of our knowledge, these are the first provably secure threshold cryptosystems realized using the Asmuth-Bloom secret sharing. Proposed schemes are comparable in performance ...

We describe an elliptic curve encryption scheme, PSEC (provably secure elliptic curve encryption scheme), which has two versions: PSEC-1 and PSEC-2. PSEC-1 is a public-key encryption system that uses the elliptic curve ElGamal trapdoor function and a random function (hash function). PSEC-2 is a public-key encryption system that uses the elliptic curve ElGamal trapdoor function, two random funct...

In this work, we study the cryptographic primitive: signcryption, which combines the functionalities of digital signatures and public-key encryption. We first propose two generic transforms from meta-ElGamal signature schemes to signcryption schemes. These constructions can be thought of as generalisations of the signcryption schemes by Zheng and Gamage et al. Our results show that a large clas...