Key-tree based private authentication has been proposed by Molnar and Wagner as a neat way to efficiently solve the problem of privacy preserving authentication based on symmetric key cryptography. However, in the key-tree based approach, the level of privacy provided by the system to its members may decrease considerably if some members are compromised. In this paper, we analyze this problem, ...

The “PYRAMIDS” Block Cipher is a symmetric encryption algorithm of a 64, 128, 256-bit plaintext block, that accepts a variable key length of 128, 192, 256 bits. The algorithm is an iterated cipher consisting of repeated applications of simple round transformations with different operations and different sequences in each round.

One of the most basic requirements concerning Boolean functions used in cryptosystems is that they must have high algebraic degrees. This simple criterion is not always well adapted to the concrete situation in which Boolean functions are used in symmetric cryptography, since changing one or several output bits of a Boolean function considerably changes its algebraic degree while it may not cha...

During the last few years considerable effort has been devoted to research related to chaotic encryption. In this paper a new symmetric key cryptosystem that exploits the idea of nonlinear mappings and their fixed points to encrypt information is presented. Furthermore, a measure of the quality of the keys used is introduced. The experimental results indicate that the proposed cryptosystem is e...

7.1 Cryptography . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 7.1.1 Overview of Cryptography . . . . . . . . . . . 130 7.1.2 Symmetric-Key Cryptography . . . . . . . . 130 7.1.3 Substitution and Transposition Techniques . . . . . . . . . . . . . . . . . . . . . . . . . 131 7.1.4 Data Encryption Standard (DES) . . . . . 133 7.1.5 Advanced Encryption Standard (AES) . 134 7.1.6 Public...

The problem of (stateless, symmetric-key) broadcast encryption, in which a central authority sends encrypted content that can be decrypted only by a designated subset of potential receivers, has been the focus of a significant amount of attention. Here, we consider a generalization of this problem in which all members of the group may act as both sender and receiver. The parameters of interest ...

A R T I C L E I N F O A B S T R A C T Article history: Received: 14 March, 2017 Accepted: 20 April, 2017 Online: 13 June, 2017 Classical cryptography is a way of disguising the news done by the people when there was no computer. The goal is to protect information by way of encoding. This paper describes a modification of classical algorithms to make cryptanalis difficult to steal undisclosed me...

We report a break for a recently proposed class of cryptosystems. The cryptosystem uses constant points of a periodic secret orbit to encrypt the plaintext. In order to break the system, it suffices to sort the constant points and find the initial fixed point. We also report breaks for the modified versions of the cryptosystem. Besides, we discuss some efficiency issues of the the cryptosystem.

In this paper we apply the cryptographic finite state machine approach as introduced in [1] to the design of symmetric key block ciphers.

The challenge-response technique is widely adapted for authentication of portable communication systems. For authentication the user can prove his/her identity via a secret shared key. However, this implies that the server requires secure storage and organization of a bulky database for the shared keys of all users. Evidently, such a sensitive and large database increases both maintenance loadi...