salsa20

Documentation

Overview

Package salsa20 implements the Salsa20 stream cipher as specified in https://cr.yp.to/snuffle/spec.pdf.

Salsa20 differs from many other stream ciphers in that it is message orientated rather than byte orientated. Keystream blocks are not preserved between calls, therefore each side must encrypt/decrypt data with the same segmentation.

Another aspect of this difference is that part of the counter is exposed as a nonce in each call. Encrypting two different messages with the same (key, nonce) pair leads to trivial plaintext recovery. This is analogous to encrypting two different messages with the same key with a traditional stream cipher.

This package also implements XSalsa20: a version of Salsa20 with a 24-byte nonce as specified in https://cr.yp.to/snuffle/xsalsa-20081128.pdf. Simply passing a 24-byte slice as the nonce triggers XSalsa20.

Index

• func XORKeyStream(out, in []byte, nonce []byte, key *[32]byte)

Functions

func XORKeyStream

func XORKeyStream(out, in []byte, nonce []byte, key *[32]byte)

XORKeyStream crypts bytes from in to out using the given key and nonce. In and out may be the same slice but otherwise should not overlap. Nonce must be either 8 or 24 bytes long.