<?php
if (class_exists('ParagonIE_Sodium_Core_ChaCha20_IetfCtx', false)) {
return;
}
/**
* Class ParagonIE_Sodium_Core_ChaCha20_IetfCtx
*/
class ParagonIE_Sodium_Core_ChaCha20_IetfCtx extends ParagonIE_Sodium_Core_ChaCha20_Ctx
{
/**
* ParagonIE_Sodium_Core_ChaCha20_IetfCtx 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 $counter The initial counter value.
* Defaults to 4 0x00 bytes.
* @throws InvalidArgumentException
* @throws TypeError
*/
public function __construct($key = '', $iv = '', $counter = '')
{
if (self::strlen($iv) !== 12) {
throw new InvalidArgumentException('ChaCha20 expects a 96-bit nonce in IETF mode.');
}
parent::__construct($key, self::substr($iv, 0, 8), $counter);
if (!empty($counter)) {
$this->container[12] = self::load_4(self::substr($counter, 0, 4));
}
$this->container[13] = self::load_4(self::substr($iv, 0, 4));
$this->container[14] = self::load_4(self::substr($iv, 4, 4));
$this->container[15] = self::load_4(self::substr($iv, 8, 4));
}
}
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