International Journal of Advanced Networking and Applications

Said F. El-Zoghdy ¹, Yasser A. Nada ², A. A. Abdo ³

Affiliations
1 Computer Science Dep., College of Computers & Information Technology, Taif University, SA
2 Computer Science Dep. College of Computers & Information Technology, Taif University, SA
3 Department of Mathematics & Computer Science, Menoufia University, EG

Abstract

Digital Images and video encryption plays an important role in today’s multimedia world. Many encryption schemes have been proposed to provide security for digital images. Usually the symmetric key ciphering algorithms are used in encrypting digital images because it is fast and use the techniques for block and stream ciphers. Data Encryption Standard is symmetric key encryption algorithm. In spite of the successful cracking of the data encryption standard by massive brute force attacks, data encryption standard algorithm is an entrenched technology and still useful for many purposes. In this paper, we use some of the image quality encryption measuring factors to study the effect of data encryption standard algorithm in image ciphering. The results show that the data encryption standard algorithm is fast and it achieves a good encryption rate for image ciphering using different modes of operation.

Keywords

Image Encryption, Key Ciphering Algorithms, DES.

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I. A. Ismail ¹, S. F. El-Zoghdy ², A. A. Abdo ²

Affiliations
1 Department of Information Technology, Zagazig University, Zagazig, EG
2 Department of Mathematics and Computer Science, Menoufia University, EG

Abstract

Digital signature scheme is an important research topic in cryptography. An ordinary digital signature scheme allows a signer to create signatures of documents and the generated signatures can be verified by any person. A proxy signature scheme, a variation of ordinary digital signature scheme, enables a proxy signer to sign messages on behalf of the original signer. To be used in different applications, many proxy signatures schemes were proposed. Among them, Soe and Lee nominative Proxy Signature scheme, and Jianhong Zhang, Jianhong Zou, and Yumin Wang nominative Proxy Signature scheme for mobile communication. The authors of these schemes argued that their schemes satisfies the following security requirements:user anonymity, authentication and non-repudiation. However, in this paper, we show that their schemes do not satisfy the non-repudiation among their security requirements. And then we propose a new nominative proxy signature scheme that solves the weakness of their schemes. Unlike their schemes, the proposed scheme provides a non-repudiation property and moreover it is more secure than their schemes.

Keywords

Nominative Signature, Proxy Signature, Digital Signature, Cryptanalysis.

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