ParagonIE_Sodium_Core32_ChaCha20_IetfCtx::__construct( string $key = '', string $iv = '', string $counter = '' )

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    }