Salsa20 Algorithm

Salsa20 is a stream cipher designed by Daniel J. Bernstein and submitted in 2005 to the eSTREAM European Union cryptographic validation process. It generates a pseudorandom keystream from a key, nonce and counter using repeated rounds of addition, rotation and exclusive-or operations arranged in a 4x4 matrix of words, which is then combined with the plaintext to produce ciphertext. Its later variant, ChaCha, changed the round function to increase diffusion and improve performance on some hardware.