Problem
According to the comment provided here, the mcrypt-extension is deprecated and will be deleted in PHP 7.2. As a result, I’m looking for a different technique to encrypt passwords.
I’m currently utilizing something similar to
mcrypt_encrypt(MCRYPT_RIJNDAEL_128, md5($key, true), $string, MCRYPT_MODE_CBC, $iv)
I’d want to hear your thoughts on the best/strongest technique to encrypt passwords. The encrypted password should, of course, be supported by PHP 7.xx and should also be decryptable, because my clients want to be able to’recover’ their passwords without having to generate a new one.
Asked by Piet
Solution #1
It’s best to hash passwords so that they can’t be decrypted. For attackers who may have acquired access to your database or files, this makes things slightly more difficult.
A guide on secure encryption/decryption is provided at https://paragonie.com/white-paper/2015-secure-php-data-encryption if you need to encrypt and decrypt your data. To summarize the following link:
Answered by Phil
Solution #2
You can use the openssl encrypt/openssl decrypt PHP functions instead, as suggested by @rqLizard, which is a far superior way to implement AES (Advanced Encryption Standard), often known as Rijndael encryption.
Scott’s comment on php.net is as follows:
Further reading:
<?php
//$key should have been previously generated in a cryptographically safe way, like openssl_random_pseudo_bytes
$plaintext = "message to be encrypted";
$cipher = "aes-128-gcm";
if (in_array($cipher, openssl_get_cipher_methods()))
{
$ivlen = openssl_cipher_iv_length($cipher);
$iv = openssl_random_pseudo_bytes($ivlen);
$ciphertext = openssl_encrypt($plaintext, $cipher, $key, $options=0, $iv, $tag);
//store $cipher, $iv, and $tag for decryption later
$original_plaintext = openssl_decrypt($ciphertext, $cipher, $key, $options=0, $iv, $tag);
echo $original_plaintext."\n";
}
?>
<?php
//$key previously generated safely, ie: openssl_random_pseudo_bytes
$plaintext = "message to be encrypted";
$ivlen = openssl_cipher_iv_length($cipher="AES-128-CBC");
$iv = openssl_random_pseudo_bytes($ivlen);
$ciphertext_raw = openssl_encrypt($plaintext, $cipher, $key, $options=OPENSSL_RAW_DATA, $iv);
$hmac = hash_hmac('sha256', $ciphertext_raw, $key, $as_binary=true);
$ciphertext = base64_encode( $iv.$hmac.$ciphertext_raw );
//decrypt later....
$c = base64_decode($ciphertext);
$ivlen = openssl_cipher_iv_length($cipher="AES-128-CBC");
$iv = substr($c, 0, $ivlen);
$hmac = substr($c, $ivlen, $sha2len=32);
$ciphertext_raw = substr($c, $ivlen+$sha2len);
$original_plaintext = openssl_decrypt($ciphertext_raw, $cipher, $key, $options=OPENSSL_RAW_DATA, $iv);
$calcmac = hash_hmac('sha256', $ciphertext_raw, $key, $as_binary=true);
if (hash_equals($hmac, $calcmac))//PHP 5.6+ timing attack safe comparison
{
echo $original_plaintext."\n";
}
?>
Based on the preceding examples, I’ve modified the following code to encrypt the user’s session id:
class Session {
/**
* Encrypts the session ID and returns it as a base 64 encoded string.
*
* @param $session_id
* @return string
*/
public function encrypt($session_id) {
// Get the MD5 hash salt as a key.
$key = $this->_getSalt();
// For an easy iv, MD5 the salt again.
$iv = $this->_getIv();
// Encrypt the session ID.
$encrypt = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $key, $session_id, MCRYPT_MODE_CBC, $iv);
// Base 64 encode the encrypted session ID.
$encryptedSessionId = base64_encode($encrypt);
// Return it.
return $encryptedSessionId;
}
/**
* Decrypts a base 64 encoded encrypted session ID back to its original form.
*
* @param $encryptedSessionId
* @return string
*/
public function decrypt($encryptedSessionId) {
// Get the MD5 hash salt as a key.
$key = $this->_getSalt();
// For an easy iv, MD5 the salt again.
$iv = $this->_getIv();
// Decode the encrypted session ID from base 64.
$decoded = base64_decode($encryptedSessionId);
// Decrypt the string.
$decryptedSessionId = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key, $decoded, MCRYPT_MODE_CBC, $iv);
// Trim the whitespace from the end.
$session_id = rtrim($decryptedSessionId, "\0");
// Return it.
return $session_id;
}
public function _getIv() {
return md5($this->_getSalt());
}
public function _getSalt() {
return md5($this->drupal->drupalGetHashSalt());
}
}
into:
class Session {
const SESS_CIPHER = 'aes-128-cbc';
/**
* Encrypts the session ID and returns it as a base 64 encoded string.
*
* @param $session_id
* @return string
*/
public function encrypt($session_id) {
// Get the MD5 hash salt as a key.
$key = $this->_getSalt();
// For an easy iv, MD5 the salt again.
$iv = $this->_getIv();
// Encrypt the session ID.
$ciphertext = openssl_encrypt($session_id, self::SESS_CIPHER, $key, $options=OPENSSL_RAW_DATA, $iv);
// Base 64 encode the encrypted session ID.
$encryptedSessionId = base64_encode($ciphertext);
// Return it.
return $encryptedSessionId;
}
/**
* Decrypts a base 64 encoded encrypted session ID back to its original form.
*
* @param $encryptedSessionId
* @return string
*/
public function decrypt($encryptedSessionId) {
// Get the Drupal hash salt as a key.
$key = $this->_getSalt();
// Get the iv.
$iv = $this->_getIv();
// Decode the encrypted session ID from base 64.
$decoded = base64_decode($encryptedSessionId, TRUE);
// Decrypt the string.
$decryptedSessionId = openssl_decrypt($decoded, self::SESS_CIPHER, $key, $options=OPENSSL_RAW_DATA, $iv);
// Trim the whitespace from the end.
$session_id = rtrim($decryptedSessionId, '\0');
// Return it.
return $session_id;
}
public function _getIv() {
$ivlen = openssl_cipher_iv_length(self::SESS_CIPHER);
return substr(md5($this->_getSalt()), 0, $ivlen);
}
public function _getSalt() {
return $this->drupal->drupalGetHashSalt();
}
}
To be clear, the above transformation is not a real conversion because the two encryptions use different block sizes and encrypted data. MCRYPT RIJNDAEL only supports non-standard null padding, therefore the default padding is different. @zaph
Additional observations (taken from @zaph’s comments):
Answered by kenorb
Solution #3
The best approach I found is to use OpenSSL, as mentioned by previous responses here. There is no need for an additional library because it is incorporated within PHP. Here are some straightforward examples:
To encrypt:
function encrypt($key, $payload) {
$iv = openssl_random_pseudo_bytes(openssl_cipher_iv_length('aes-256-cbc'));
$encrypted = openssl_encrypt($payload, 'aes-256-cbc', $key, 0, $iv);
return base64_encode($encrypted . '::' . $iv);
}
To decrypt:
function decrypt($key, $garble) {
list($encrypted_data, $iv) = explode('::', base64_decode($garble), 2);
return openssl_decrypt($encrypted_data, 'aes-256-cbc', $key, 0, $iv);
}
Reference link: https://www.shift8web.ca/2017/04/how-to-encrypt-and-execute-your-php-code-with-mcrypt/
Answered by Ariston Cordeiro
Solution #4
Rijndael has a pure-PHP implementation, phpseclib, which is accessible as a composer package and runs on PHP 7.3. (tested by me).
On the phpseclib docs, there’s a page that creates sample code when you enter the fundamental variables (cipher, mode, key size, bit size). For Rijndael, ECB, 256, 256, it produces the following:
a code generated by mycrypt
$decoded = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, ENCRYPT_KEY, $term, MCRYPT_MODE_ECB);
works with the library in this manner
$rijndael = new \phpseclib\Crypt\Rijndael(\phpseclib\Crypt\Rijndael::MODE_ECB);
$rijndael->setKey(ENCRYPT_KEY);
$rijndael->setKeyLength(256);
$rijndael->disablePadding();
$rijndael->setBlockLength(256);
$decoded = $rijndael->decrypt($term);
* $term was decoded in base64.
Answered by Pentium10
Solution #5
The phpseclib pollyfill package can be used. With rijndael 256, you can’t use open ssl or libsodium to encrypt or decrypt. Another issue is that no code needs to be replaced.
Answered by Ahmet Erkan ÇELİK
Post is based on https://stackoverflow.com/questions/41272257/mcrypt-is-deprecated-what-is-the-alternative