In this paper presents the Linear Cryptanalysis on S-DES and Symmetric Block Ciphers Using Hill Cipher Method. As a vehicle of demonstration of this concept, choose simple yet representative block ciphers such as computationally tractable versions of S-DES, for the studies. The attack presented in this paper is applicable to block structure independently of the key scheduling. The attack needs distinct known plaintexts which are a more realistic attack model in comparison with impossible differential cryptanalysis which uses chosen plaintext pairs. Moreover, linear cryptanalysis on simplified data encryption standard performed simulations on a small variant block and present the experimental results on the theoretical model of the multidimensional linear cryptanalysis using Hill Cipher method. General TermsSimplified Data Encryption Standard, Symmetric Block Cipher.

Encryption is used to securely transmit data in open networks. Each type of data has its own features; therefore different techniques should be used to protect confidential image data from unauthorized access. In this paper we propose a novel concept of combined partial image encryption using phase manipulation and sign encryption. Entire encryption process involves two stages where image to be encrypted are applied to phase manipulation block. In first stage Fourier Transform (FT) is applied to get phase and magnitude of the input image. Phase of the image are scrambled to get modified image after applying Inverse Fourier Transform. In second stage the modified image is partially encrypted by using sign encryption. Sign Encryption finally gives resultant partially encrypted image by extracting the sign bits of modified image. Experiment is conducted for an image using MATLAB software. From the experiment we obtained partially encrypted image at the end of encryption process. Decryption process employs exactly reverse process of encryption which results in the reconstructed images.