src/AESGCM.php
private static function common($K, $key_length, $IV, $A)
    {
        $H = openssl_encrypt(str_repeat("\0", 16), 'aes-'.($key_length).'-ecb', $K, OPENSSL_NO_PADDING | OPENSSL_RAW_DATA); //---
        $iv_len = self::getLength($IV);

        if (96 === $iv_len) {
            $J0 = $IV.pack('H*', '00000001');
        } else {
            $s = self::calcVector($IV);
            Assertion::eq(($s + 64) % 8, 0, 'Unable to decrypt or to verify the tag.');

            $packed_iv_len = pack('N', $iv_len);
            $iv_len_padding = str_pad($packed_iv_len, 8, "\0", STR_PAD_LEFT);
            $hash_X = $IV.str_pad('', ($s + 64) / 8, "\0").$iv_len_padding;
            $J0 = self::getHash($H, $hash_X);
        }
        $v = self::calcVector($A);
        $a_len_padding = self::addPadding($A);

        return [$J0, $v, $a_len_padding, $H];
    }
private static function common($K, $key_length, $IV, $A)
    {
        $H = openssl_encrypt(str_repeat("\0", 16), 'aes-'.($key_length).'-ecb', $K, OPENSSL_NO_PADDING | OPENSSL_RAW_DATA); //---
        $iv_len = self::getLength($IV);

        if (96 === $iv_len) {
            $J0 = $IV.pack('H*', '00000001');
        } else {
            $s = self::calcVector($IV);
            Assertion::eq(($s + 64) % 8, 0, 'Unable to decrypt or to verify the tag.');

            $packed_iv_len = pack('N', $iv_len);
            $iv_len_padding = str_pad($packed_iv_len, 8, "\0", STR_PAD_LEFT);
            $hash_X = $IV.str_pad('', ($s + 64) / 8, "\0").$iv_len_padding;
            $J0 = self::getHash($H, $hash_X);
        }
        $v = self::calcVector($A);
        $a_len_padding = self::addPadding($A);

        return [$J0, $v, $a_len_padding, $H];
    }
@param $K
@param $key_length
@param $IV
@param $A

@return array