Upgrading my encryption library from Mcrypt to OpenSSL

Question

I am using the below commonly referenced library for encryption. I want to upgrade it to OpenSSL from Mcrypt so that I am no longer using a deprecated library.

I'm trying to find out if this is even possible. I've done some research on this, but I've found conflicting information:

This post says that it is impossible to decrypt data using OpenSSL that was encrypted with Mcrypt. https://stackoverflow.com/a/19748494/5834657

However, this post says that it is possible using padding. It appears that my function uses padding. Is this the right type of padding needed to make this work? https://stackoverflow.com/a/31614770/5834657

<?php   namespace Utilities\Encryption;  /** * A class to handle secure encryption and decryption of arbitrary data * * Note that this is not just straight encryption.  It also has a few other * features in it to make the encrypted data far more secure.  Note that any * other implementations used to decrypt data will have to do the same exact *  operations.   * * Security Benefits: * * - Uses Key stretching * - Hides the Initialization Vector * - Does HMAC verification of source data * */  class Encryption {  /**  * @var string $cipher The mcrypt cipher to use for this instance  */ protected $cipher = '';  /**  * @var int $mode The mcrypt cipher mode to use  */ protected $mode = '';  /**  * @var int $rounds The number of rounds to feed into PBKDF2 for key generation  */ protected $rounds = 100;  /**  * Constructor!  *  * @param string $cipher The MCRYPT_* cypher to use for this instance  * @param int    $mode   The MCRYPT_MODE_* mode to use for this instance  * @param int    $rounds The number of PBKDF2 rounds to do on the key  */ public function __construct($cipher, $mode, $rounds = 100) {     $this->cipher = $cipher;     $this->mode = $mode;     $this->rounds = (int) $rounds; }  /**  * Decrypt the data with the provided key  *  * @param string $data The encrypted datat to decrypt  * @param string $key  The key to use for decryption  *   * @returns string|false The returned string if decryption is successful  *                           false if it is not  */ public function decrypt($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;     }      $dec = mcrypt_decrypt($this->cipher, $cipherKey, $enc, $this->mode, $iv);      $data = $this->unpad($dec);      return $data; }  /**  * Encrypt the supplied data using the supplied key  *   * @param string $data The data to encrypt  * @param string $key  The key to encrypt with  *  * @returns string The encrypted data  */ public function encrypt($data, $key) {     $salt = mcrypt_create_iv(128, MCRYPT_DEV_URANDOM);     list ($cipherKey, $macKey, $iv) = $this->getKeys($salt, $key);      $data = $this->pad($data);      $enc = mcrypt_encrypt($this->cipher, $cipherKey, $data, $this->mode, $iv);      $mac = hash_hmac('sha512', $enc, $macKey, true);     return $salt . $enc . $mac; }  /**  * Generates a set of keys given a random salt and a master key  *  * @param string $salt A random string to change the keys each encryption  * @param string $key  The supplied key to encrypt with  *  * @returns array An array of keys (a cipher key, a mac key, and a IV)  */ protected function getKeys($salt, $key) {     $ivSize = mcrypt_get_iv_size($this->cipher, $this->mode);     $keySize = mcrypt_get_key_size($this->cipher, $this->mode);     $length = 2 * $keySize + $ivSize;      $key = $this->pbkdf2('sha512', $key, $salt, $this->rounds, $length);      $cipherKey = substr($key, 0, $keySize);     $macKey = substr($key, $keySize, $keySize);     $iv = substr($key, 2 * $keySize);     return array($cipherKey, $macKey, $iv); }  /**  * Stretch the key using the PBKDF2 algorithm  *  * @see http://en.wikipedia.org/wiki/PBKDF2  *  * @param string $algo   The algorithm to use  * @param string $key    The key to stretch  * @param string $salt   A random salt  * @param int    $rounds The number of rounds to derive  * @param int    $length The length of the output key  *  * @returns string The derived key.  */ protected function pbkdf2($algo, $key, $salt, $rounds, $length) {     $size   = strlen(hash($algo, '', true));     $len    = ceil($length / $size);     $result = '';     for ($i = 1; $i <= $len; $i++) {         $tmp = hash_hmac($algo, $salt . pack('N', $i), $key, true);         $res = $tmp;         for ($j = 1; $j < $rounds; $j++) {              $tmp  = hash_hmac($algo, $tmp, $key, true);              $res ^= $tmp;         }         $result .= $res;     }     return substr($result, 0, $length); }  protected function pad($data) {     $length = mcrypt_get_block_size($this->cipher, $this->mode);     $padAmount = $length - strlen($data) % $length;     if ($padAmount == 0) {         $padAmount = $length;     }     return $data . str_repeat(chr($padAmount), $padAmount); }  protected function unpad($data) {     $length = mcrypt_get_block_size($this->cipher, $this->mode);     $last = ord($data[strlen($data) - 1]);     if ($last > $length) return false;     if (substr($data, -1 * $last) !== str_repeat(chr($last), $last)) {         return false;     }     return substr($data, 0, -1 * $last);  } } 

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Update: I have been trying to decrypt a string encrypted with Mcrypt using OpenSSL by converting the library to OpenSSL.

Then, I'm encrypting a string using a key using the above code, and trying to decrypt that value using the below code and the same key. However I'm just getting a blank response. If I comment out:

$data = $this->unpad($dec)

in the decrypt function I get a string but it is just jumbled up characters (Much like it looks when it's first encrypted.)

<?php   namespace Utilities\Encryption;  /** * A class to handle secure encryption and decryption of arbitrary data * * Note that this is not just straight encryption.  It also has a few other *  features in it to make the encrypted data far more secure.  Note that any *  other implementations used to decrypt data will have to do the same exact *  operations.   * * Security Benefits: * * - Uses Key stretching * - Hides the Initialization Vector * - Does HMAC verification of source data * */ class EncryptionOpenSsl {  /**  * @var string $cipher The mcrypt cipher to use for this instance  */ protected $cipher = '';  /**  * @var int $mode The mcrypt cipher mode to use  */ protected $mode = '';  /**  * @var int $rounds The number of rounds to feed into PBKDF2 for key generation  */ protected $rounds = 100;  /**  * Constructor!  *  * @param string $cipher The MCRYPT_* cypher to use for this instance  * @param int    $mode   The MCRYPT_MODE_* mode to use for this instance  * @param int    $rounds The number of PBKDF2 rounds to do on the key  */ public function __construct($cipher, $rounds = 100) {     $this->cipher = $cipher;     // $this->mode = MCRYPT_MODE_CBC;     $this->rounds = (int) $rounds; }  /**  * Decrypt the data with the provided key  *  * @param string $data The encrypted datat to decrypt  * @param string $key  The key to use for decryption  *   * @returns string|false The returned string if decryption is successful  *                           false if it is not  */ public function decrypt($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, $key, OPENSSL_RAW_DATA, $iv);     // $dec = mcrypt_decrypt($this->cipher, $cipherKey, $enc, $this->mode, $iv);      $data = $this->unpad($dec);      return $data; }  /**  * Encrypt the supplied data using the supplied key  *   * @param string $data The data to encrypt  * @param string $key  The key to encrypt with  *  * @returns string The encrypted data  */ public function encrypt($data, $key) {     $salt = mcrypt_create_iv(128, MCRYPT_DEV_URANDOM);     list ($cipherKey, $macKey, $iv) = $this->getKeys($salt, $key);      $data = $this->pad($data);      $enc = mcrypt_encrypt($this->cipher, $cipherKey, $data, $this->mode, $iv);      $mac = hash_hmac('sha512', $enc, $macKey, true);     return $salt . $enc . $mac; }  /**  * Generates a set of keys given a random salt and a master key  *  * @param string $salt A random string to change the keys each encryption  * @param string $key  The supplied key to encrypt with  *  * @returns array An array of keys (a cipher key, a mac key, and a IV)  */ protected function getKeys($salt, $key) {     $ivSize = mcrypt_get_iv_size(MCRYPT_BLOWFISH, MCRYPT_MODE_CBC);     $keySize = mcrypt_get_key_size(MCRYPT_BLOWFISH, MCRYPT_MODE_CBC);     $length = 2 * $keySize + $ivSize;      $key = $this->pbkdf2('sha512', $key, $salt, $this->rounds, $length);      $cipherKey = substr($key, 0, $keySize);     $macKey = substr($key, $keySize, $keySize);     $iv = substr($key, 2 * $keySize);     return array($cipherKey, $macKey, $iv); }  /**  * Stretch the key using the PBKDF2 algorithm  *  * @see http://en.wikipedia.org/wiki/PBKDF2  *  * @param string $algo   The algorithm to use  * @param string $key    The key to stretch  * @param string $salt   A random salt  * @param int    $rounds The number of rounds to derive  * @param int    $length The length of the output key  *  * @returns string The derived key.  */ protected function pbkdf2($algo, $key, $salt, $rounds, $length) {     $size   = strlen(hash($algo, '', true));     $len    = ceil($length / $size);     $result = '';     for ($i = 1; $i <= $len; $i++) {         $tmp = hash_hmac($algo, $salt . pack('N', $i), $key, true);         $res = $tmp;         for ($j = 1; $j < $rounds; $j++) {              $tmp  = hash_hmac($algo, $tmp, $key, true);              $res ^= $tmp;         }         $result .= $res;     }     return substr($result, 0, $length); }  protected function pad($data) {     $length = mcrypt_get_block_size(MCRYPT_BLOWFISH, MCRYPT_MODE_CBC);     $padAmount = $length - strlen($data) % $length;     if ($padAmount == 0) {         $padAmount = $length;     }     return $data . str_repeat(chr($padAmount), $padAmount); }  protected function unpad($data) {     $length = mcrypt_get_block_size(MCRYPT_BLOWFISH, MCRYPT_MODE_CBC);     $last = ord($data[strlen($data) - 1]);     if ($last > $length) return false;     if (substr($data, -1 * $last) !== str_repeat(chr($last), $last)) {         return false;     }     return substr($data, 0, -1 * $last);  } } 

Answer 1

This code for your decryption routine works for me:

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; } 

Test:

$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"; } 

If you can confirm it works for you as well I can tidy up the answer and add final working code.