leigh/chacha20

Pure PHP implementation of the ChaCha20 encryption algorithm.

ChaCha20 in PHP

This library contains a pure PHP implementation of the ChaCha20 encryption algorithm., _(*1)

The library has been written to be high performance (relative to PHP), not pretty. It obviously doesn't perform anywhere close to a native implementation., _(*2)

Usage:

Remember that a nonce must not be used more than once for a particular key, _(*3)

$chacha20 = new ChaCha20\Cipher;
$encCtx = $chacha20->init($key, $nonce);
$decCtx = $chacha20->init($key, $nonce);

$cipherText = $chacha20->encrypt($encCtx, $message);
$plainText = $chacha20->decrypt($decCtx, $cipherText);

The Context object maintains the current state of the algorithm, so that it can be used in a streaming scenario. Therefore an application performing simultaneous encryption and decryption will need to main two contexts., _(*4)

The decrypt method is an alias of the encrypt method, and exists only to indicate intent., _(*5)

Seek operations can be performed on the keystream by calling the setCounter method, where the count is in 64-byte blocks., _(*6)