ParagonIE_Sodium_Core32_ChaCha20_IetfCtx

10class ParagonIE_Sodium_Core32_ChaCha20_IetfCtx extends ParagonIE_Sodium_Core32_ChaCha20_Ctx11{12    /**13     * ParagonIE_Sodium_Core_ChaCha20_IetfCtx constructor.14     *15     * @internal You should not use this directly from another application16     *17     * @param string $key     ChaCha20 key.18     * @param string $iv      Initialization Vector (a.k.a. nonce).19     * @param string $counter The initial counter value.20     *                        Defaults to 4 0x00 bytes.21     * @throws InvalidArgumentException22     * @throws SodiumException23     * @throws TypeError24     */25    public function __construct($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}