Cryptographic algorithms for confidentiality and authentication play a major important role in nowadays information security Sen (2012) [1]. Encryption algorithms are becoming more necessary to ensure the securely transmitted data over insecure communication channels. A new stream cipher is proposed. The design is very simple and based on 16 shift registers, nonlinear and an output function. The proposed algorithm is characterized by a high performance in software with measured encryption/decryption on Pentium IV processor. We have performed detailed security analysis, in particular, and standard statistical randomness test of the produced ciphertext. Experimental results in terms of performance and resources are presented.Ó 2014 Production and hosting by Elsevier B.V. on behalf of Ain Shams University.

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Cryptographic hash functions are an important tool in cryptography for applications such as digital signature of messages, message authentication, and key derivation. This paper presents a new cryptographic keyed hash function design, named Concrete Hash function Algorithm, CHA-128, which has some difference from the popular hash function designs and used for ensuring integrity of messages to a higher degree to suit the fast growing network applications. The function structure is designed permit a wide variety of implementation tradeoffs. Also CHA is proposed as very smooth 128 bit hash function algorithm, which is designed according to permit a wide variety of computing implementation tradeoffs. By very smooth, it means that the smoothness bound is multiple fixed sequential functions. A valuable comparison between the software performance of CHA-128 design and some popular hash function algorithms designs is performed.

The Virtual Private Network (VPN) technology provides a way of protecting information being transmitted over unsecure network. VPN uses encryption to provide data confidentiality and data integrity but does not provide or enforce strong user authentication. This paper proposes a new symmetric encryption algorithm for special purpose VPN to secure the classified data. The proposed algorithm based non Feistel structure with well-designed substitution boxes (S-Box), permutation networks, and a serial-parallel construction functions, in addition to key derivation algorithm which used the input secret key to generate sub-keys input for proposed algorithm. The security analysis of the proposed was conducted and the National Institute of Standards and technology statistical tests have been applied to the output of the algorithm proving its secrecy and randomness properties. In addition, the performance of the proposed algorithm has measured per the execution time comparing with the standard algorithm.

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