How to Migrate from Mcrypt to OpenSSL for Data Encryption in PHP?

Implementing OpenSSL in Place of Mcrypt for Encryption

In the PHP application that currently utilizes Mcrypt for data encryption, there is a need to substitute Mcrypt with OpenSSL. The original implementation employed blowfish cipher in ECB mode, but replacing Mcrypt with OpenSSL poses a challenge due to different encryption outcomes and required IV lengths.

Understanding the Discrepancies

Both encryption functions, mcrypt_encrypt and openssl_encrypt, produce different results. Additionally, mcrypt requires a 56-byte IV for blowfish-ecb, while openssl uses a zero-length IV. These differences stem from the different padding algorithms used by Mcrypt (PKCS#5) and OpenSSL (PKCS#7).

Addressing Encryption Differences

To mitigate the encryption discrepancies, manual padding of data with PKCS#7 padding is necessary before encrypting with mcrypt. This ensures compatibility with the padding algorithm used by OpenSSL. The following example demonstrates this approach:

$key = "anotherpassword1";
$str = "does it work 12";

$enc = mcrypt_encrypt(MCRYPT_BLOWFISH, $key, $str."", MCRYPT_MODE_ECB);
$dec = mcrypt_decrypt(MCRYPT_BLOWFISH, $key, $enc, MCRYPT_MODE_ECB);
echo(bin2hex($enc).PHP_EOL); // Encrypted data
var_dump($dec); // Decrypted data

$enc = openssl_encrypt($str, 'bf-ecb', $key, true);
$dec = openssl_decrypt($enc, 'bf-ecb', $key, true);
echo(bin2hex($enc).PHP_EOL); // Encrypted data
var_dump($dec); // Decrypted data

Migration Considerations

Since decrypting data encrypted with Mcrypt using OpenSSL is impractical, the only solution is to re-encrypt the data. This poses a significant migration effort, as all previously encrypted data must be re-encrypted using OpenSSL.

The above is the detailed content of How to Migrate from Mcrypt to OpenSSL for Data Encryption in PHP?. For more information, please follow other related articles on the PHP Chinese website!