Text Encryption Algorithms based on Pseudo Random Number Generator

This paper presents algorithms for encryption and decryption developed using pseudo random number generator (PRNG) and non-Linear functions. PRNG used in the work are matlab random number generator (RNG) and Linear congruential generator (LCG). The developed algorithms are named according to PRNG used in it. State of PRNG is considered as secret key of the cipher. The encryption schemes have been cryptanalyzed for four different methods to test its strength like key space analysis, plaintext and key sensitive test. Known plaintext attack is also performed by taking into consideration a small string of plaintext and the complete cipher text for small text. The analysis is performed on different keys selected randomly from key space for various texts and files. Key sensitivity up to 50 % and plaintext sensitivity ranging from 3% to 50 % have been obtained in the developed ciphers. It is concluded that proposed encryption algorithms have strength against linear, differential and statistical attacks.