Encrypt with Crypto.JS and decrypt with PHP 7.3 - php

I'm upgrading my code from PHP 5.6 to 7.3 which is a Woocommerce Plugin for my Ionic app. In the meantime I noted that mcrypt_decrypt is deprecated in PHP 7. I tried to figured out how to change my code, but it still does not return the same string. Here is my encryption code in the app:
var password = this.password;
if (this.appConfig.App_Secret != '') {
var key = CryptoJS.enc.Utf8.parse(CryptoJS.MD5(this.appConfig.App_Secret).toString());
var iv = CryptoJS.enc.Utf8.parse(CryptoJS.MD5(this.appConfig.App_Secret).toString().substr(0, 16));
password = CryptoJS.AES.encrypt(password, key, { iv: iv }).toString();
}
And this is my old decryption code in PHP:
$iv=substr(md5(get_option('sow_rest_api_secret')),0,16);
$key = md5(get_option('sow_rest_api_secret'));
$data = base64_decode($decrypt_str);
$result = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key, $data, MCRYPT_MODE_CBC, $iv);
return rtrim($result,"\0");
I change the line with the $result variable from
$result = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key, $data, MCRYPT_MODE_CBC, $iv);
to
$result = openssl_decrypt($data, 'aes-128-gcm', $key, $options=OPENSSL_RAW_DATA, $iv);
Can you give support?

Quoting this php.net comment:
Also, MCRYPT_RIJNDAEL_256 is not AES-256, it's a different variant of the Rijndael block cipher. If you want AES-256 in mcrypt, you have to use MCRYPT_RIJNDAEL_128 with a 32-byte key. OpenSSL makes it more obvious which mode you are using (i.e. 'aes-128-cbc' vs 'aes-256-ctr').
This means that you've been using AES-256 before, and not AES-128.
Furthermore, CryptoJS uses CBC mode by default, as correctly noted by #Topaco.
Putting this together:
$result = openssl_decrypt($data, 'aes-256-cbc', $key, $options=OPENSSL_RAW_DATA, $iv);
should give the same result, as your previous mcrypt_decrypt solution.

Related

Decode encoded data in PHP 7.2

I was using "mcrypt-*" for decoding the response in previous PHP 5.6 version but now in PHP 7.2 version as it is deprecated I am using openSSL method. But it is not working properly hopefully I am missing something.
$value="###lllljG5ZOibDGtlL gcQLAtTQUnCJ/bE2glWsL1WKVPdC22c9GtGe/Npx9Uv9IYaszOAVXB4T9s7Hsss/2XpZ9oisx5M4jeV7RK2S/JrBt2E4GEcDGwuJs6NhkKV8hdOcU tmkJLxO3OJ OgVbqrT6a4v5RE7w eP zvQwZyAR5cYCKUYomou9mL/pvfLbe RrBe5ZnMQmUrD6cwUxEE/inikMvIb4K7HI fVPid N B3iPnIYQna6/v9W5A0kslBj6BBDjVXJabwmCSDVxbArm0GDNseWoQAEa4BMxYitqP6cVTxL5Kri8xbAKCW5/unnYnudkHQjNJWW7LuiwDxsBqwQv8D/R/Ff/joFW6q0 muI16/CfIoFnYAyAJWNlKCX9";
$value = urldecode($value);
$value = str_replace(" ", "+", $value);
$abc = triple_decrypt($value);
print_r($abc);
PHP 5.6 working fine
function triple_decrypt($input){
$key = "thisis87658748639testkey";
$input = base64_decode($input);
$td = mcrypt_module_open(MCRYPT_TripleDES, "", MCRYPT_MODE_ECB, "");
$iv = mcrypt_create_iv(mcrypt_enc_get_iv_size ($td), MCRYPT_RAND);
mcrypt_generic_init($td, $key, $iv);
$pwd = trim(mdecrypt_generic($td, $input), "\x00..\x0F");
mcrypt_generic_end($td);
return $pwd;
}
PHP 7.2
function triple_decrypt($input){
$key = "thisis87658748639testkey";
$cipher = "des-ede3";
$ivlen = openssl_cipher_iv_length($cipher);
$iv = openssl_random_pseudo_bytes($ivlen);
$pwd = openssl_decrypt($input, $cipher, $key, $options=0, $iv);
return $pwd;
}
openssl uses PKCS7-padding and mcrypt Zero-padding [0][1][2]. To decrypt the ciphertext with openssl, openssl's padding must be disabled and mcrypt's Zero-padding bytes must be removed:
function triple_decrypt($input){
$key = "thisis87658748639testkey";
$cipher = "des-ede3";
$decrypted = openssl_decrypt($input, $cipher, $key, $options=OPENSSL_ZERO_PADDING); // Disable openssl's PKCS7-padding
$unpadded = trim($decrypted, "\x00..\x0F"); // Remove mcrypt's Zero-padding bytes
return $unpadded;
}
However, note the following with regard to a reimplementation of encryption and decryption: ECB is an insecure mode [3]. Instead, CBC or even better GCM should be used [4][5]. Instead of Triple-DES the modern and faster todays standard AES is recommended [6]. Zero-padding is unreliable, PKCS7-padding should be applied instead.
Furthermore, the mcrypt code is to some extent inconsistent:
The ECB mode doesn't use an IV (this is also the reason why openssl_cipher_iv_length returns 0 in the openssl code [7]). mcrypt_generic_init ignores the IV in case of the ECB mode [8], so it's not used in the mcrypt code and therefore not needed in the openssl code.
And if a mode would be used that requires an IV, then the following would have to be considered: The IV is always needed for encryption and decryption. Therefore, a random IV is generated (and used) during encryption and then passed on to the recipient together with the ciphertext, where it's used for decryption. Since the IV isn't secret, it's usually prefixed to the ciphertext. The generation of a random IV during decryption therefore makes no sense.
You can do using openssl()
function encryptIt($q) {
$cryptKey = 'YourProjectname'; //any string
$encryptionMethod = "AES-256-CBC";
$secretHash = "25c6c7rr35b9979b151f0205cd13b0vv"; // any hash
//To encrypt
$qEncoded = openssl_encrypt($q, $encryptionMethod, $secretHash);
return $qEncoded;
}
function decryptIt($q) {
$cryptKey = 'YourProjectname'; //any string
$encryptionMethod = "AES-256-CBC";
$secretHash = "25c6c7rr35b9979b151f0205cd13b0vv"; // any hash
//To Decrypt
$qDecoded = openssl_decrypt($q, $encryptionMethod, $secretHash);
return $qDecoded;
}
$encryptedstring = encryptIt('TEST');
echo "<br/>";
echo decryptIt($encryptedstring);

Decrypt string that is encrypted by MCRYPT_RIJNDAEL_128

I used following codes to encrypt and decrypt the strings in php. I recently upgraded my server and now i can see that the codes i use is depreciated. Encryption code is hardcoded on my app so i need to decrypt on the server. Please provide the alternative to both encrypt and decrypt
Code for encryption.
function encrypt($data = '', $key = 'chiperbase65enus')
{
$encrypted = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $key, $data, MCRYPT_MODE_CBC, 'chiperbase65enus');
return base64_encode($encrypted);
}
And for decryption is below. I dont actually need encryption anymore but decryption is the must.
function decrypt($data = '', $key = 'chiperbase65enus')
{
$decrypted = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key, base64_decode($data), MCRYPT_MODE_CBC,'chiperbase65enus');
return rtrim($decrypted, "\0");
}
$decrypted = openssl_decrypt(base64_decode($encrypted_string), "AES-128-CBC", "chiperbase65enus",OPENSSL_RAW_DATA | OPENSSL_ZERO_PADDING, "chiperbase65enus");
I found the solution...

m_crypt() is deprecated in PHP 7.2 [duplicate]

The mcrypt-extension is deprecated will be removed in PHP 7.2 according to the comment posted here. So I am looking for an alternative way to encrypt passwords.
Right now I am using something like
mcrypt_encrypt(MCRYPT_RIJNDAEL_128, md5($key, true), $string, MCRYPT_MODE_CBC, $iv)
I need your opinion for the best/strongest way to encrypt passwords, the encrypted password should of course supported by PHP 7.xx and should also be decryptable because my customers do want to have an option to 'recover' their passwords without generating a new one.
It's best practice to hash passwords so they are not decryptable. This makes things slightly more difficult for attackers that may have gained access to your database or files.
If you must encrypt your data and have it decryptable, a guide to secure encryption/decryption is available at https://paragonie.com/white-paper/2015-secure-php-data-encryption. To summarize that link:
Use Libsodium - A PHP extension
If you can't use Libsodium, use defuse/php-encryption - Straight PHP code
If you can't use Libsodium or defuse/php-encryption, use OpenSSL - A lot of servers will already have this installed. If not, it can be compiled with --with-openssl[=DIR]
As suggested by #rqLizard, you can use openssl_encrypt/openssl_decrypt PHP functions instead which provides a much
better alternative to implement AES (The Advanced Encryption Standard) also known as Rijndael encryption.
As per the following Scott's comment at php.net:
If you're writing code to encrypt/encrypt data in 2015, you should use openssl_encrypt() and openssl_decrypt(). The underlying library (libmcrypt) has been abandoned since 2007, and performs far worse than OpenSSL (which leverages AES-NI on modern processors and is cache-timing safe).
Also, MCRYPT_RIJNDAEL_256 is not AES-256, it's a different variant of the Rijndael block cipher. If you want AES-256 in mcrypt, you have to use MCRYPT_RIJNDAEL_128 with a 32-byte key. OpenSSL makes it more obvious which mode you are using (i.e. aes-128-cbc vs aes-256-ctr).
OpenSSL also uses PKCS7 padding with CBC mode rather than mcrypt's NULL byte padding. Thus, mcrypt is more likely to make your code vulnerable to padding oracle attacks than OpenSSL.
Finally, if you are not authenticating your ciphertexts (Encrypt Then MAC), you're doing it wrong.
Further reading:
Using Encryption and Authentication Correctly (for PHP developers).
If You're Typing the Word MCRYPT Into Your PHP Code, You're Doing It Wrong.
Code examples
Example #1
AES Authenticated Encryption in GCM mode example for PHP 7.1+
<?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 $original_plaintext."\n";
}
?>
Example #2
AES Authenticated Encryption example for PHP 5.6+
<?php
//$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";
}
?>
Example #3
Based on above examples, I've changed the following code which aims at encrypting 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 $this->drupal->drupalGetHashSalt();
}
}
To clarify, above change is not a true conversion since the two encryption uses a different block size and a different encrypted data. Additionally, the default padding is different, MCRYPT_RIJNDAEL only supports non-standard null padding. #zaph
Additional notes (from the #zaph's comments):
Rijndael 128 (MCRYPT_RIJNDAEL_128) is equivalent to AES, however Rijndael 256 (MCRYPT_RIJNDAEL_256) is not AES-256 as the 256 specifies a block size of 256-bits, whereas AES has only one block size: 128-bits. So basically Rijndael with a block size of 256-bits (MCRYPT_RIJNDAEL_256) has been mistakenly named due to the choices by the mcrypt developers. #zaph
Rijndael with a block size of 256 may be less secure than with a block size of 128-bits because the latter has had much more reviews and uses. Secondly, interoperability is hindered in that while AES is generally available, where Rijndael with a block size of 256-bits is not.
Encryption with different block sizes for Rijndael produces different encrypted data.
For example, MCRYPT_RIJNDAEL_256 (not equivalent to AES-256) defines a different variant of the Rijndael block cipher with size of 256-bits and a key size based on the passed in key, where aes-256-cbc is Rijndael with a block size of 128-bits with a key size of 256-bits. Therefore they're using different block sizes which produces entirely different encrypted data as mcrypt uses the number to specify the block size, where OpenSSL used the number to specify the key size (AES only has one block size of 128-bits). So basically AES is Rijndael with a block size of 128-bits and key sizes of 128, 192 and 256 bits. Therefore it's better to use AES, which is called Rijndael 128 in OpenSSL.
As detailed by other answers here, the best solution I found is using OpenSSL. It is built into PHP and you don't need any external library. Here are simple examples:
To encrypt:
function encrypt($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/
Pure-PHP implementation of Rijndael exists with phpseclib available as composer package and works on PHP 7.3 (tested by me).
There's a page on the phpseclib docs, which generates sample code after you input the basic variables (cipher, mode, key size, bit size). It outputs the following for Rijndael, ECB, 256, 256:
a code with mycrypt
$decoded = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, ENCRYPT_KEY, $term, MCRYPT_MODE_ECB);
works like this with the library
$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);
* $term was base64_decoded
You can use phpseclib pollyfill package. You can not use open ssl or libsodium for encrypt/decrypt with rijndael 256.
Another issue, you don't need replacement any code.
You should use OpenSSL over mcrypt as it's actively developed and maintained. It provides better security, maintainability and portability. Secondly it performs AES encryption/decryption much faster. It uses PKCS7 padding by default, but you can specify OPENSSL_ZERO_PADDING if you need it. To use with a 32-byte binary key, you can specify aes-256-cbc which is much obvious than MCRYPT_RIJNDAEL_128.
Here is the code example using Mcrypt:
Unauthenticated AES-256-CBC encryption library written in Mcrypt with PKCS7 padding.
/**
* This library is unsafe because it does not MAC after encrypting
*/
class UnsafeMcryptAES
{
const CIPHER = MCRYPT_RIJNDAEL_128;
public static function encrypt($message, $key)
{
if (mb_strlen($key, '8bit') !== 32) {
throw new Exception("Needs a 256-bit key!");
}
$ivsize = mcrypt_get_iv_size(self::CIPHER);
$iv = mcrypt_create_iv($ivsize, MCRYPT_DEV_URANDOM);
// Add PKCS7 Padding
$block = mcrypt_get_block_size(self::CIPHER);
$pad = $block - (mb_strlen($message, '8bit') % $block, '8bit');
$message .= str_repeat(chr($pad), $pad);
$ciphertext = mcrypt_encrypt(
MCRYPT_RIJNDAEL_128,
$key,
$message,
MCRYPT_MODE_CBC,
$iv
);
return $iv . $ciphertext;
}
public static function decrypt($message, $key)
{
if (mb_strlen($key, '8bit') !== 32) {
throw new Exception("Needs a 256-bit key!");
}
$ivsize = mcrypt_get_iv_size(self::CIPHER);
$iv = mb_substr($message, 0, $ivsize, '8bit');
$ciphertext = mb_substr($message, $ivsize, null, '8bit');
$plaintext = mcrypt_decrypt(
MCRYPT_RIJNDAEL_128,
$key,
$ciphertext,
MCRYPT_MODE_CBC,
$iv
);
$len = mb_strlen($plaintext, '8bit');
$pad = ord($plaintext[$len - 1]);
if ($pad <= 0 || $pad > $block) {
// Padding error!
return false;
}
return mb_substr($plaintext, 0, $len - $pad, '8bit');
}
}
And here is the version written using OpenSSL:
/**
* This library is unsafe because it does not MAC after encrypting
*/
class UnsafeOpensslAES
{
const METHOD = 'aes-256-cbc';
public static function encrypt($message, $key)
{
if (mb_strlen($key, '8bit') !== 32) {
throw new Exception("Needs a 256-bit key!");
}
$ivsize = openssl_cipher_iv_length(self::METHOD);
$iv = openssl_random_pseudo_bytes($ivsize);
$ciphertext = openssl_encrypt(
$message,
self::METHOD,
$key,
OPENSSL_RAW_DATA,
$iv
);
return $iv . $ciphertext;
}
public static function decrypt($message, $key)
{
if (mb_strlen($key, '8bit') !== 32) {
throw new Exception("Needs a 256-bit key!");
}
$ivsize = openssl_cipher_iv_length(self::METHOD);
$iv = mb_substr($message, 0, $ivsize, '8bit');
$ciphertext = mb_substr($message, $ivsize, null, '8bit');
return openssl_decrypt(
$ciphertext,
self::METHOD,
$key,
OPENSSL_RAW_DATA,
$iv
);
}
}
Source: If You're Typing the Word MCRYPT Into Your PHP Code, You're Doing It Wrong.
I am using this on PHP 7.2.x, it's working fine for me:
public function make_hash($userStr){
try{
/**
* Used and tested on PHP 7.2x, Salt has been removed manually, it is now added by PHP
*/
return password_hash($userStr, PASSWORD_BCRYPT);
}catch(Exception $exc){
$this->tempVar = $exc->getMessage();
return false;
}
}
and then authenticate the hash with the following function:
public function varify_user($userStr,$hash){
try{
if (password_verify($userStr, $hash)) {
return true;
}
else {
return false;
}
}catch(Exception $exc){
$this->tempVar = $exc->getMessage();
return false;
}
}
Example:
//create hash from user string
$user_password = $obj->make_hash2($user_key);
and to authenticate this hash use the following code:
if($obj->varify_user($key, $user_key)){
//this is correct, you can proceed with
}
That's all.
As pointed out, you should not be storing your users' passwords in a format that is decryptable. Reversable encryption provides an easy route for hackers to find out your users' passwords, which extends to putting your users' accounts at other sites at risk should they use the same password there.
PHP provides a pair of powerful functions for random-salted, one-way hash encryption — password_hash() and password_verify(). Because the hash is automatically random-salted, there is no way for hackers to utilize precompiled tables of password hashes to reverse-engineer the password. Set the PASSWORD_DEFAULT option and future versions of PHP will automatically use stronger algorithms to generate password hashes without you having to update your code.
I was able to translate my Crypto object
Get a copy of php with mcrypt to decrypt the old data. I went to http://php.net/get/php-7.1.12.tar.gz/from/a/mirror, compiled it, then added the ext/mcrypt extension (configure;make;make install). I think I had to add the extenstion=mcrypt.so line to the php.ini as well. A series of scripts to build intermediate versions of the data with all data unencrypted.
Build a public and private key for openssl
openssl genrsa -des3 -out pkey.pem 2048
(set a password)
openssl rsa -in pkey.pem -out pkey-pub.pem -outform PEM -pubout
To Encrypt (using public key) use openssl_seal. From what I've read, openssl_encrypt using an RSA key is limited to 11 bytes less than the key length (See http://php.net/manual/en/function.openssl-public-encrypt.php comment by Thomas Horsten)
$pubKey = openssl_get_publickey(file_get_contents('./pkey-pub.pem'));
openssl_seal($pwd, $sealed, $ekeys, [ $pubKey ]);
$encryptedPassword = base64_encode($sealed);
$key = base64_encode($ekeys[0]);
You could probably store the raw binary.
To Decrypt (using private key)
$passphrase="passphrase here";
$privKey = openssl_get_privatekey(file_get_contents('./pkey.pem'), $passphrase);
// I base64_decode() from my db columns
openssl_open($encryptedPassword, $plain, $key, $privKey);
echo "<h3>Password=$plain</h3>";
P.S. You can't encrypt the empty string ("")
P.P.S. This is for a password database not for user validation.
You should use openssl_encrypt() function.

Failing to upgrade mcrypt to openssl decryption in PHP

I'm upgrading a legacy application from PHP 7.0 to 7.2 and my decrypt function isn't working when I switch out mcrypt for openssl.
I tried the existing answers like mcrypt is deprecated, what is the alternative?, and Gists like https://gist.github.com/odan/c1dc2798ef9cedb9fedd09cdfe6e8e76, but I'm still not able to make the code work.
Can anyone shed some light what I'm doing wrong?
Old code
function decrypt($value, $key) {
$ivLength = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
$iv = substr($value, 0, $ivLength);
return rtrim(
mcrypt_decrypt(
MCRYPT_RIJNDAEL_128,
hash('sha256', $key, true),
substr($value, $ivLength),
MCRYPT_MODE_CBC,
$iv
),
"\0"
);
}
New code (not working with existing inputs)
function decrypt($value, $key) {
$ivLength = openssl_cipher_iv_length('AES-128-CBC');
$iv = substr($value, 0, $ivLength);
// Note: $key is hashed because it was hashed in the old encrypt function below
return openssl_decrypt(substr($value, $ivLength), 'AES-128-CBC', hash('sha256', $key, true), OPENSSL_RAW_DATA | OPENSSL_ZERO_PADDING, $iv);
}
For context, here's how the old code encrypted the values:
function encrypt($value, $key) {
$iv = mcrypt_create_iv(mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC), MCRYPT_DEV_URANDOM);
return $iv . mcrypt_encrypt(
MCRYPT_RIJNDAEL_128,
hash('sha256', $key, true),
$value,
MCRYPT_MODE_CBC,
$iv
);
}
Also, the raw value in $value is twice as long when output to the error log in the new code than the old code and looks similar but with more characters.
The main issue here is the key size. You're creating the key with SHA256 which returns a 256 bit hash, therefore you're using AES / Rijndael with a 256 bit key.
The number in Rijndael-128 defines the block size, the key size is determined by the length of the key we use. The number in AES-128 defines the key size (the block size is constant, 128 bits), and if the actual key length is different than this number, then the key is shortened or expanded (with zero bytes) to fit the selected key size.
This means that your mcrypt code uses Rijndael-128 (AES) with a 256 bit key, in CBC mode. The openssl equivalent is AES-256-CBC, and if we use this algorithm then mcrypt and openssl should produce compatible results.
function decrypt_mcrypt_with_openssl($value, $key) {
$iv = substr($value, 0, 16);
$ciphertext = substr($value, 16);
$key = hash('sha256', $key, true);
$plaintext = openssl_decrypt(
$ciphertext, 'AES-256-CBC', $key,
OPENSSL_RAW_DATA | OPENSSL_ZERO_PADDING,
$iv
);
return rtrim($plaintext, "\0");
}
SHA256 is not suitable as a key derivation function. If you're deriving your key from a password you can use hash_pbkdf2 with a random salt and a high enough number of iterations. Or you could create a cryptographically secure pseudo-random key with openssl_random_pseudo_bytes.
I think it's best to stop using mcrypt completely and use only openssl. Mcrypt doesn't support PKCS7 padding, it doesn't provide any authenticated encryption algorithms, and it is not being maintained anymore.

PHP7.1 mcrypt alternative

Mcrypt function has been deprecated as of PHP 7.1.0.
My deprecated string encode / decode functions:
$key: secret key
$str: string
$encoded = base64_encode(mcrypt_encrypt(MCRYPT_RIJNDAEL_256, md5($key), $str, MCRYPT_MODE_CBC, md5(md5($key))));
$decoded = rtrim(mcrypt_decrypt(MCRYPT_RIJNDAEL_256, md5($key), base64_decode($str), MCRYPT_MODE_CBC, md5(md5($key))), "\0");
Can you suggest some alternatives?
You should use openssl_encrypt instead.
Consider using defuse or RNCryptor, they provide a complete solution, are being maintained and is correct.
For MCRYPT_RIJNDAEL_256 I posted a full answer for PHP7.3 here: https://stackoverflow.com/a/53937314/243782
snippet:
works like this with the phpseclib library
$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);
echo encrypt_openssl($str, $key);
function encrypt_openssl($msg, $key, $iv = null) {
$iv_size = openssl_cipher_iv_length('AES-256-CBC');
if (!$iv) {
$iv = openssl_random_pseudo_bytes($iv_size);
}
$encryptedMessage = openssl_encrypt($msg, 'AES-256-CBC', $key, OPENSSL_RAW_DATA, $iv);
return base64_encode($iv . $encryptedMessage);
}
mcrypt may be removed in PHP 7.1 alternative openssl
As mentioned above, open_ssl is a good alternative for mcrypt.
The only problem I had with open_ssl, is that it cannot be used for large strings.
I wrote a script (static class), which overcomes this problem (large strings are split up in chunks and encrypted/decrypted separately in the background).
See public gist:
https://gist.github.com/petermuller71/33616d55174d9725fc00a663d30194ba

Categories