1<?php
  2
  3if (class_exists('ParagonIE_Sodium_Core_ChaCha20_IetfCtx', false)) {
  4    return;
  5}
  6
  7/**
  8 * Class ParagonIE_Sodium_Core32_ChaCha20_IetfCtx
  9 */
 10class ParagonIE_Sodium_Core32_ChaCha20_IetfCtx extends ParagonIE_Sodium_Core32_ChaCha20_Ctx
 11{
 12    /**
 13     * ParagonIE_Sodium_Core_ChaCha20_IetfCtx constructor.
 14     *
 15     * @internal You should not use this directly from another application
 16     *
 17     * @param string $key     ChaCha20 key.
 18     * @param string $iv      Initialization Vector (a.k.a. nonce).
 19     * @param string $counter The initial counter value.
 20     *                        Defaults to 4 0x00 bytes.
 21     * @throws InvalidArgumentException
 22     * @throws SodiumException
 23     * @throws TypeError
 24     */
 25    public function __construct($key = '', $iv = '', $counter = '')
 26    {
 27        if (self::strlen($iv) !== 12) {
 28            throw new InvalidArgumentException('ChaCha20 expects a 96-bit nonce in IETF mode.');
 29        }
 30        parent::__construct($key, self::substr($iv, 0, 8), $counter);
 31
 32        if (!empty($counter)) {
 33            $this->container[12] = ParagonIE_Sodium_Core32_Int32::fromReverseString(self::substr($counter, 0, 4));
 34        }
 35        $this->container[13] = ParagonIE_Sodium_Core32_Int32::fromReverseString(self::substr($iv, 0, 4));
 36        $this->container[14] = ParagonIE_Sodium_Core32_Int32::fromReverseString(self::substr($iv, 4, 4));
 37        $this->container[15] = ParagonIE_Sodium_Core32_Int32::fromReverseString(self::substr($iv, 8, 4));
 38    }
 39}
 40