<?php
if (class_exists('ParagonIE_Sodium_Core_ChaCha20_Ctx', false)) {
return;
}
class ParagonIE_Sodium_Core_ChaCha20_Ctx extends ParagonIE_Sodium_Core_Util implements ArrayAccess
{
protected $container;
public function __construct($key = '', $iv = '', $counter = '')
{
if (self::strlen($key) !== 32) {
throw new InvalidArgumentException('ChaCha20 expects a 256-bit key.');
}
if (self::strlen($iv) !== 8) {
throw new InvalidArgumentException('ChaCha20 expects a 64-bit nonce.');
}
$this->container = new SplFixedArray(16);
$this->container[0] = 0x61707865;
$this->container[1] = 0x3320646e;
$this->container[2] = 0x79622d32;
$this->container[3] = 0x6b206574;
$this->container[4] = self::load_4(self::substr($key, 0, 4));
$this->container[5] = self::load_4(self::substr($key, 4, 4));
$this->container[6] = self::load_4(self::substr($key, 8, 4));
$this->container[7] = self::load_4(self::substr($key, 12, 4));
$this->container[8] = self::load_4(self::substr($key, 16, 4));
$this->container[9] = self::load_4(self::substr($key, 20, 4));
$this->container[10] = self::load_4(self::substr($key, 24, 4));
$this->container[11] = self::load_4(self::substr($key, 28, 4));
if (empty($counter)) {
$this->container[12] = 0;
$this->container[13] = 0;
} else {
$this->container[12] = self::load_4(self::substr($counter, 0, 4));
$this->container[13] = self::load_4(self::substr($counter, 4, 4));
}
$this->container[14] = self::load_4(self::substr($iv, 0, 4));
$this->container[15] = self::load_4(self::substr($iv, 4, 4));
}
public function offsetSet($offset, $value)
{
if (!is_int($offset)) {
throw new InvalidArgumentException('Expected an integer');
}
if (!is_int($value)) {
throw new InvalidArgumentException('Expected an integer');
}
$this->container[$offset] = $value;
}
public function offsetExists($offset)
{
return isset($this->container[$offset]);
}
public function offsetUnset($offset)
{
unset($this->container[$offset]);
}
public function offsetGet($offset)
{
return isset($this->container[$offset]) ? $this->container[$offset] : null;
}
}