<?php
declare(strict_types=1);
if (class_exists('ParagonIE_Sodium_Core_ChaCha20_Ctx', false)) {
return;
}
/**
* Class ParagonIE_Sodium_Core_ChaCha20_Ctx
*
* @template-implements ArrayAccess<int>
* @psalm-suppress MissingTemplateParam
*/
class ParagonIE_Sodium_Core_ChaCha20_Ctx extends ParagonIE_Sodium_Core_Util implements ArrayAccess
{
/**
* @var SplFixedArray internally, <int, int>
*/
protected SplFixedArray $container;
/**
* ParagonIE_Sodium_Core_ChaCha20_Ctx constructor.
*
* @internal You should not use this directly from another application
*
* @param string $key ChaCha20 key.
* @param string $iv Initialization Vector (a.k.a. nonce).
* @param string $counter The initial counter value.
* Defaults to 8 0x00 bytes.
* @throws InvalidArgumentException
* @throws TypeError
*/
public function __construct(
#[SensitiveParameter]
string $key = '',
string $iv = '',
string $counter = ''
) {
if (self::strlen($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);
/* "expand 32-byte k" as per ChaCha20 spec */
$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));
}
/**
* @internal You should not use this directly from another application
*
* @param int $offset
* @param int $value
* @return void
*/
#[ReturnTypeWillChange]
public function offsetSet($offset, $value): void
{
$this->container[$offset] = $value;
}
/**
* @internal You should not use this directly from another application
*
* @param int $offset
* @return bool
*/
#[ReturnTypeWillChange]
public function offsetExists($offset)
{
return isset($this->container[$offset]);
}
/**
* @internal You should not use this directly from another application
*
* @param int $offset
* @return void
*/
#[ReturnTypeWillChange]
public function offsetUnset($offset): void
{
unset($this->container[$offset]);
}
/**
* @internal You should not use this directly from another application
*
* @param int $offset
* @return mixed|null
*/
#[ReturnTypeWillChange]
public function offsetGet($offset)
{
return isset($this->container[$offset])
? $this->container[$offset]
: null;
}
}
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