Upgrading my encryption library from Mcrypt to OpenSSL

Can I upgrade my encryption library from Mcrypt to OpenSSL? In OpenSSL, is it possible to decrypt data encrypted with Mcrypt? Two different posts provide conflicting information.

Question: Is it possible to upgrade my encryption library from Mcrypt to OpenSSL? If so, how?

Answer: Yes, it is possible to upgrade your encryption library from Mcrypt to OpenSSL.

Question: Can I decrypt data encrypted with Mcrypt using OpenSSL?

Answer: Yes, it is possible to decrypt data encrypted with Mcrypt using OpenSSL.

Here is a code example of how you can decrypt data encrypted with Mcrypt using OpenSSL:

public function decrypt($data, $key) {
    $salt = substr($data, 0, 128);
    $enc = substr($data, 128, -64);
    $mac = substr($data, -64);

    list ($cipherKey, $macKey, $iv) = $this->getKeys($salt, $key);

    if ($mac !== hash_hmac('sha512', $enc, $macKey, true)) {
        return false;
    }

    $dec = openssl_decrypt($enc, $this->cipher, $cipherKey, OPENSSL_RAW_DATA, $iv);

    return $dec;
}

Additional Notes:

• The openssl_decrypt() function requires the iv parameter to be the same length as the block size of the cipher being used.
• If the iv parameter is not the same length as the block size of the cipher being used, you will need to use the openssl_decrypt() function in CBC mode.

Test:

The following code can be used to test the decrypt() function:

$keys = [
    'this is a secret key.',
    'G906m70p(IhzA5T&5x7(w0%a631)u)%D6E79cIYJQ!iP2U(xT13q6)tJ6gZ3D2wi&0")7cP5',
    chr(6) . chr(200) . chr(16) . 'my key ' . chr(3) . chr(4) . chr(192) . chr(254) . ' zyx0987!!',
    'and finally one more key to test with here:',
];


$data = [
    'A',
    'This is a test',
    'now test encrypting something a little bit longer with 1234567890.',
    '$length = mcrypt_get_block_size(MCRYPT_BLOWFISH, MCRYPT_MODE_CBC); $last = ord($data[strlen($data) - 1]);',
    'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec sit amet pharetra urna. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Ut fringilla, quam sed eleifend eleifend, justo turpis consectetur tellus, quis tristique eros erat at nibh. Nunc dictum neque vel diam molestie fermentum. Pellentesque dignissim dui quis tortor eleifend, ut maximus elit egestas. Donec posuere odio et auctor porta. Quisque placerat condimentum maximus. Curabitur luctus dolor eget sem luctus, in dignissim tortor venenatis. Mauris eget nulla nisl.',
];

$failures = 0;

foreach ($data as $datum) {
    foreach ($keys as $key) {
        $enc = new Encryption(MCRYPT_BLOWFISH, MCRYPT_MODE_CBC);

        $encrypted = $enc->encrypt($datum, $key);

        $dec = new EncryptionOpenSsl('bf-cbc');

        $decrypted = $dec->decrypt($encrypted, $key);

        if (strcmp($datum, $decrypted) !== 0) {
            echo "Encryption with key '$key' of '$datum' failed.  '$decrypted' != '$datum'<br><br>\n\n";
            $failures++;
        }
    }
}

if ($failures) {
    echo "$failures tests failed.<br>\n";
} else {
    echo "ALL OKAY<br>\n";
}