A New Guess-and-Determine Method for Cryptanalysis of the GSM Encryption

Cryptanalysis is the process of finding flaws or oversights in an encryption algorithm. Nearly, all algorithms are carefully examined through cryptanalysis to determine security system which algorithm has been employed. A5/1 a well-known inbuilt mobile phone for securing GSM communication, and therefore, this also important. consists three linear feedback registers lengths 23, 22, 19 bits. Due nonlinear clocking mechanism A5/1, cryptanalytic attacks guess-and-determine (GD) nature efficient more successful. In paper, we propose new low keystream GD attack on A5/1. The basic idea guessing some portion determining remaining via relationship between register’s state known intercepted keystream. guessed determined validated by running cipher forward from that state. If matches generated keystream, accept it. Otherwise, discard try again. computational complexity success rate proposed O 2 52 96.6%, respectively.