ParagonIE_Sodium_Core_ChaCha20_IetfCtx::__construct( string $key = '', string $iv = '', string $counter = '' )

24    public function __construct($key = '', $iv = '', $counter = '')25    {26        if (self::strlen($iv) !== 12) {27            throw new InvalidArgumentException('ChaCha20 expects a 96-bit nonce in IETF mode.');28        }29        $counter = $this->initCounter($counter);30        parent::__construct($key, self::substr($iv, 0, 8), $counter);31        $this->container[12] = self::load_4(self::substr($counter, 0, 4));32        $this->container[13] = self::load_4(self::substr($iv, 0, 4));33        $this->container[14] = self::load_4(self::substr($iv, 4, 4));34        $this->container[15] = self::load_4(self::substr($iv, 8, 4));35    }