Decrypt string in node.js from PHP RIJNDAEL_128 CBC - php

Question

I'm trying to decrypt a string, previously encrypted by a third party software using PHP RIJNDAEL_128 in CBC mode, using node.js.
Here is an interactive link of the following PHP code, in a sandbox, so you can compile and see for yourself. http://sandbox.onlinephpfunctions.com/code/504a7d052c5b123fac8103a073c05c2ff5f80571
PHP source code:
<?php
class CryptClass{
private $key;
public function __construct($key){
$this->key = $key;
}
public function cryptage($message){
$key = base64_decode($this->key);
$iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
$iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
$ciphertext = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $key, $message, MCRYPT_MODE_CBC, $iv);
$ciphertext = $iv . $ciphertext;
return base64_encode($ciphertext);
}
public function decryptage($message){
$key = base64_decode($this->key);
$iv_size2 = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
$ciphertext_dec = base64_decode($message);
$iv_dec = substr($ciphertext_dec, 0, $iv_size2);
$ciphertext_dec = substr($ciphertext_dec, $iv_size2);
$message_decrypt = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key,$ciphertext_dec, MCRYPT_MODE_CBC, $iv_dec);
return str_replace("\0", "", $message_decrypt);
}
}
// Secret key and data
define('KEY', 'azertyuiolskzif');
define('DATA', 'user#email.com|1477576941|origin.com');
// Crypt
$Crypt = new CryptClass(base64_encode(KEY));
$encodedData = base64_encode($Crypt->cryptage(DATA));
// Decrypt
$decodedData = $Crypt->decryptage(base64_decode($encodedData));
echo 'base64_encode: '.base64_encode(KEY);
echo "\nDATA: ".DATA;
echo "\nDATA length: ".strlen(DATA);
echo "\n\nencodedData: ".$encodedData;
echo "\n\ndata: ".$decodedData;
echo "\n\ndata length: ".strlen($decodedData);
echo "\n\ncrypt/decrypt match?: ".(DATA == $decodedData ? 'yes':'no');
Here is my implementation in node.js: NOT WORKING, see below for working solution
var crypto = require('crypto');
var textToEncrypt = 'user#email.com|1477576941|origin.com';
var encryptionMethod = 'AES-128-CBC';
var secret = "azertyuiolskzif";
var iv = 'aaaabbbbccccdddd';
var encrypt = function (plain_text, encryptionMethod, secret, iv) {
var encryptor = crypto.createCipheriv(encryptionMethod, secret, iv);
return encryptor.update(plain_text, 'utf8', 'base64') + encryptor.final('base64');
};
var decrypt = function (encryptedMessage, encryptionMethod, secret, iv) {
var decryptor = crypto.createDecipheriv(encryptionMethod, secret, iv);
return decryptor.update(encryptedMessage, 'base64', 'utf8') + decryptor.final('utf8');
};
var encryptedMessage = encrypt(textToEncrypt, encryptionMethod, secret, iv);
var decryptedMessage = decrypt(encryptedMessage, encryptionMethod, secret, iv);
console.log(decrypt());
console.log(encryptedMessage);
console.log(decryptedMessage);
I have tried many things and I'm getting lost here between Invalid key length and other error messages. One thing I don't quite understand is that the KEY apparently used to encrypt the data is azertyuiolskzif which is 15 chars long while most script use a required 32 chars string... Maybe PHP doesn't need a 32 char string but Node does?
Or maybe it's related to the difference between 128 and 256. Or is it due to the difference of padding between PHp and Node implementation?
I tried to follow the advices given at Encrypt string in PHP and decrypt in Node.js but even tho, I didn't succeed at encrypting my data in node yet.
Edit:
After some more digging around (and thanks for the explanations in the answers), I finally made crypt/decrypt work in Node.js. But I haven't succeeded to decrypt something crypted by PHP yet.
var crypto = require('crypto');
var AES = {};
AES.encrypt = function(dataToEncrypt, encryptionMethod, secret, iv, padding) {
var encipher = crypto.createCipheriv(encryptionMethod, secret, iv);
encipher.setAutoPadding(padding || 0); // "true" or "128" would work with aes-128-cbc
var encryptedData = encipher.update(dataToEncrypt, 'utf8', 'base64');
encryptedData += encipher.final('base64');
return encryptedData;
};
AES.decrypt = function(encryptedData, encryptionMethod, secret, iv, padding) {
var decipher = crypto.createDecipheriv(encryptionMethod, secret, iv);
decipher.setAutoPadding(padding || 0); // "true" or "128" would work with aes-128-cbc
var decoded = decipher.update(encryptedData, 'base64', 'utf8');
decoded += decipher.final('utf8');
return decoded;
};
// ----
var textToEncrypt = 'user#email.com|1477576941|origin.com';
var secret = "aaaabbbbccccdddd"; // Must be 16 chars
var iv = crypto.randomBytes(16); // Must be 16 chars
var encryptionMethod = 'AES-128-CBC';
// Testing crypt/decrypt using Node.js algorithm.
var encryptedMessage = AES.encrypt(textToEncrypt, encryptionMethod, secret, iv, 128);
var decryptedMessage = AES.decrypt(encryptedMessage, encryptionMethod, secret, iv, 128);
console.log('encryptedMessage', encryptedMessage); // Displays "GWpMWORNKkqlrHJDPuNgSmTKr1vJhaAApHP+ssK3SH5EALTkdWneUZRp9PXNpVQ2"
console.log('decryptedMessage', decryptedMessage); // Displays "user#email.com|1477576941|origin.com"
// Testing decrypt from a string generated by PHP algorithm.
// XXX Doesn't work "Error: error:0606506D:digital envelope routines:EVP_DecryptFinal_ex:wrong final block length"
// XXX Probably due to wrong padding between PHP/Node implementation?
var stringToDecode = 'RlM3Wkl3N3JRM0dnaEh4SkdoZWFDRy9mZGRoTnkxNlZUL2IvcHl4TkdzUUlRSXQwSWNwWUZ5OFpaRENZQys3S2t0bFZIUWoweUVsZGxUU21sYU9tS0E9PQ==';
console.log('stringToDecode', stringToDecode);
console.log(AES.decrypt(
stringToDecode,
encryptionMethod, secret, iv, 128
));

Answer 1

AES keys must be exactly one of 128, 192 or 256-bits. Some implementations will pad keys in some way but this should not be relied on. Make the key a correct size.