An Improvement of Linear Cipher Using Public Tables, Pairs of Moduli, and Periodic Keys

Sukanya Homwong, Thotsaphon Thongjunthug


In this paper, we propose an improvement of the linear cipher using a public table, which can be used for decryption only by the recipient, and a pair of moduli to prevent successful determination of the private keys by the opponent. Our scheme also uses a periodic key for encrypting each block of plaintext and decrypting each block of ciphertext. We find that our modified linear cipher is more secure against frequency analysis, a ciphertext-only attack, and a known-plaintext attack than the classical linear cipher.             


Keywords :  cryptography, linear cipher, periodic key, pair of moduli, public table

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