Using audio noise for generating random key stream

Steam ciphers systems are widely used in cryptography applications due to low possibility of propagating errors, ease of implementation and high processing speed. A stream cipher is an encryption process where random binary stream keys combine with the plaintext to produce cipher text. The stream cipher systems encrypt bits of plaintext individually by adding bits from a key stream to plaintext bits. The security of a cipher text fully depends on the key stream. Therefore, generating a long unpredictable sequence of binary bits used as the encryption key is the main topic in stream cipher systems. This paper focuses on generating a stream of binary keys using audio noise and subjected the generated keys to several local randomness tests such as; frequency test, serial test, Poker test and Autocorrelation test. The randomness tests show that the generated keys contain good statistical characteristics and high security makes them suitable to be used in stream cipher systems.