Encrypt string in PHP and decrypt in Node.js

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I was struggling with the same problem this week but in the opposite way (PHP encrypts -> NodeJS decrypts) and had managed to get this snippet working:

aes256cbc.js

var crypto = require('crypto');

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 textToEncrypt = new Date().toISOString().substr(0,19) + '|My super secret information.';
var encryptionMethod = 'AES-256-CBC';
var secret = "My32charPasswordAndInitVectorStr"; //must be 32 char length
var iv = secret.substr(0,16);

var encryptedMessage = encrypt(textToEncrypt, encryptionMethod, secret, iv);
var decryptedMessage = decrypt(encryptedMessage, encryptionMethod, secret, iv);

console.log(encryptedMessage);
console.log(decryptedMessage);

aes256cbc.php

<?php
date_default_timezone_set('UTC');
$textToEncrypt = substr(date('c'),0,19) . "|My super secret information.";
$encryptionMethod = "AES-256-CBC";
$secret = "My32charPasswordAndInitVectorStr";  //must be 32 char length
$iv = substr($secret, 0, 16);

$encryptedMessage = openssl_encrypt($textToEncrypt, $encryptionMethod, $secret,0,$iv);
$decryptedMessage = openssl_decrypt($encryptedMessage, $encryptionMethod, $secret,0,$iv);

echo "$encryptedMessage\n";
echo "$decryptedMessage\n";
?>

The secret here to avoid falling in key/iv size/decryption problems is to have the secret of exactly 32 characters length and 16 for the IV.
Also, it is VERY important to use ‘base64’ and ‘utf8’ in NodeJS since these are the defaults in PHP.

Here are some sample runs:

$ node aes256cbc.js && php aes256cbc.php
zra3FX4iyCc7qPc1dZs+G3ZQ40f5bSw8P9n5OtWl1t86nV5Qfh4zNRPFbsciyyHyU3Qi4Ga1oTiTwzrPIZQXLw==
2015-01-27T18:29:12|My super secret information.
zra3FX4iyCc7qPc1dZs+G3ZQ40f5bSw8P9n5OtWl1t86nV5Qfh4zNRPFbsciyyHyU3Qi4Ga1oTiTwzrPIZQXLw==
2015-01-27T18:29:12|My super secret information.

$ node aes256cbc.js && php aes256cbc.php
zra3FX4iyCc7qPc1dZs+G6B6+8aavHNc/Ymv9L6Omod8Di3tMbvOa2B7O2Yiyoutm9fy9l0G+P5VJT9z2qNESA==
2015-01-27T18:29:15|My super secret information.
zra3FX4iyCc7qPc1dZs+G6B6+8aavHNc/Ymv9L6Omod8Di3tMbvOa2B7O2Yiyoutm9fy9l0G+P5VJT9z2qNESA==
2015-01-27T18:29:15|My super secret information.

$ node aes256cbc.js && php aes256cbc.php
zra3FX4iyCc7qPc1dZs+G4oD1Fr5yLByON6QDE56UOqP6kkfGJzpyH6TbwZYX2oGlh2JGv+aHYUMh0qQnAj/uw==
2015-01-27T18:29:29|My super secret information.
zra3FX4iyCc7qPc1dZs+G4oD1Fr5yLByON6QDE56UOqP6kkfGJzpyH6TbwZYX2oGlh2JGv+aHYUMh0qQnAj/uw==
2015-01-27T18:29:29|My super secret information.

$ node aes256cbc.js && php aes256cbc.php
zra3FX4iyCc7qPc1dZs+G5OVCbCaUy8a0LLF+Bn8UT4X3nYbtynO0Zt2mvXnnli9dRxrxMw43uWnkh8MIwVHXA==
2015-01-27T18:29:31|My super secret information.
zra3FX4iyCc7qPc1dZs+G5OVCbCaUy8a0LLF+Bn8UT4X3nYbtynO0Zt2mvXnnli9dRxrxMw43uWnkh8MIwVHXA==
2015-01-27T18:29:31|My super secret information.

$ node aes256cbc.js && php aes256cbc.php
fdsqSyHBJjlwD0jYfOUZM2FrONG6Fk5d7FOItYEdbnaZIhhmg/apa8/jPwKFkDXD9eNqWC3w0JzY5wjtZADiBA==
2015-01-27T18:30:08|My super secret information.
fdsqSyHBJjlwD0jYfOUZM2FrONG6Fk5d7FOItYEdbnaZIhhmg/apa8/jPwKFkDXD9eNqWC3w0JzY5wjtZADiBA==
2015-01-27T18:30:08|My super secret information.

$ node aes256cbc.js && php aes256cbc.php
fdsqSyHBJjlwD0jYfOUZM4SRfi6jG5EoDFEF6d9xCIyluXSiMaKlhd89ovpeOz/YyEIlPbYR4ly00gf6hWfKHw==
2015-01-27T18:30:45|My super secret information.
fdsqSyHBJjlwD0jYfOUZM4SRfi6jG5EoDFEF6d9xCIyluXSiMaKlhd89ovpeOz/YyEIlPbYR4ly00gf6hWfKHw==
2015-01-27T18:30:45|My super secret information.

NOTE:

I use a “timestamp|message” format to avoid man in the middle attacks. For example, if the encrypted message contains an ID to be authenticated, the MitM could capture the message and re-send it every time he wants to re-authenticate.

Therefore, I could check the timestamp on the encrypted message to be within a little time interval. This way, the same message is encrypted differently each second because of the timestamp, and could not be used out of this fixed time interval.

EDIT:

Here I was misusing the Initialization Vector (IV).
As @ArtjomB. explained, the IV should be the first part of the encrypted message, and also it should be a random value.
It’s also recommended to use a hmac value in a HTTP Header (x-hmac: *value*) in order to validate that the message was originated from a valid source (but this does not address the “re-send” message issue previously described).

Here’s the improved version, including the hmac for php and node and the IV as a part of the encrypted message:

aes256cbc.js (v2)

var crypto = require('crypto');

var encrypt = function (message, method, secret, hmac) {
    //var iv = crypto.randomBytes(16).toString('hex').substr(0,16);    //use this in production
    var iv = secret.substr(0,16);    //using this for testing purposes (to have the same encryption IV in PHP and Node encryptors)
    var encryptor = crypto.createCipheriv(method, secret, iv);
    var encrypted = new Buffer(iv).toString('base64') + encryptor.update(message, 'utf8', 'base64') + encryptor.final('base64');
    hmac.value = crypto.createHmac('md5', secret).update(encrypted).digest('hex');
    return encrypted;
};

var decrypt = function (encrypted, method, secret, hmac) {
    if (crypto.createHmac('md5', secret).update(encrypted).digest('hex') == hmac.value) {
        var iv = new Buffer(encrypted.substr(0, 24), 'base64').toString();
        var decryptor = crypto.createDecipheriv(method, secret, iv);
        return decryptor.update(encrypted.substr(24), 'base64', 'utf8') + decryptor.final('utf8');
    }
};

var encryptWithTSValidation = function (message, method, secret, hmac) {
    var messageTS = new Date().toISOString().substr(0,19) + message;
    return encrypt(messageTS, method, secret, hmac);
}

var decryptWithTSValidation = function (encrypted, method, secret, hmac, intervalThreshold) {
    var decrypted = decrypt(encrypted, method, secret, hmac);
    var now = new Date();
    var year = parseInt(decrypted.substr(0,4)), month = parseInt(decrypted.substr(5,2)) - 1,
    day = parseInt(decrypted.substr(8,2)), hour = parseInt(decrypted.substr(11,2)), 
    minute = parseInt(decrypted.substr(14,2)), second = parseInt(decrypted.substr(17,2));
    var msgDate = new Date(Date.UTC(year, month, day, hour, minute, second))
    if (Math.round((now - msgDate) / 1000) <= intervalThreshold) {
        return decrypted.substr(19);
    }
}

var message="My super secret information.";
var method = 'AES-256-CBC';
var secret = "My32charPasswordAndInitVectorStr"; //must be 32 char length
var hmac = {};

//var encrypted = encrypt(message, method, secret, hmac);
//var decrypted = decrypt(encrypted, method, secret, hmac);
var encrypted = encryptWithTSValidation(message, method, secret, hmac);
var decrypted = decryptWithTSValidation(encrypted, method, secret, hmac, 60*60*12); //60*60m*12=12h

console.log("Use HTTP header 'x-hmac: " + hmac.value + "' for validating against MitM-attacks.");
console.log("Encrypted: " + encrypted);
console.log("Decrypted: " + decrypted);

Note that crypto.createHmac(...).digest('hex') is digested with hex. This is the default in PHP for hmac.

aes256cbc.php (v2)

<?php

function encrypt ($message, $method, $secret, &$hmac) {
    //$iv = substr(bin2hex(openssl_random_pseudo_bytes(16)),0,16);    //use this in production
    $iv = substr($secret, 0, 16);        //using this for testing purposes (to have the same encryption IV in PHP and Node encryptors)
    $encrypted = base64_encode($iv) . openssl_encrypt($message, $method, $secret, 0, $iv);
    $hmac = hash_hmac('md5', $encrypted, $secret);
    return $encrypted;
}

function decrypt ($encrypted, $method, $secret, $hmac) {
    if (hash_hmac('md5', $encrypted, $secret) == $hmac) {
        $iv = base64_decode(substr($encrypted, 0, 24));
        return openssl_decrypt(substr($encrypted, 24), $method, $secret, 0, $iv);
    }
}

function encryptWithTSValidation ($message, $method, $secret, &$hmac) {
    date_default_timezone_set('UTC');
    $message = substr(date('c'),0,19) . "$message";
    return encrypt($message, $method, $secret, $hmac);
}

function decryptWithTSValidation ($encrypted, $method, $secret, $hmac, $intervalThreshold) {
    $decrypted = decrypt($encrypted, $method, $secret, $hmac);
    $now = new DateTime();
    $msgDate = new DateTime(str_replace("T"," ",substr($decrypted,0,19)));
    if (($now->getTimestamp() - $msgDate->getTimestamp()) <= $intervalThreshold) {
        return substr($decrypted,19);
    }
}

$message = "My super secret information.";
$method = "AES-256-CBC";
$secret = "My32charPasswordAndInitVectorStr";  //must be 32 char length

//$encrypted = encrypt($message, $method, $secret, $hmac);
//$decrypted = decrypt($encrypted, $method, $secret, $hmac);

$encrypted = encryptWithTSValidation($message, $method, $secret, $hmac);
$decrypted = decryptWithTSValidation($encrypted, $method, $secret, $hmac, 60*60*12); //60*60m*12=12h

echo "Use HTTP header 'x-hmac: $hmac' for validating against MitM-attacks.\n";
echo "Encrypted: $encrypted\n";
echo "Decrypted: $decrypted\n";
?>

Here are some sample runs:

$ node aes256cbc.js && php aes256cbc.php
Use HTTP header 'x-hmac: 6862972ef0f463bf48523fc9e334bb42' for validating against MitM-attacks.
Encrypted: YjE0ZzNyMHNwVm50MGswbQ==I6cAKeoxeSP5TGgtK59PotB/iG2BUSU8Y6NhAhVabN9UB+ZCTn7q2in4JyLwQiGN
Decrypted: My super secret information.
Use HTTP header 'x-hmac: 6862972ef0f463bf48523fc9e334bb42' for validating against MitM-attacks.
Encrypted: YjE0ZzNyMHNwVm50MGswbQ==I6cAKeoxeSP5TGgtK59PotB/iG2BUSU8Y6NhAhVabN9UB+ZCTn7q2in4JyLwQiGN
Decrypted: My super secret information.

$ node aes256cbc.js && php aes256cbc.php
Use HTTP header 'x-hmac: b2e63f216acde938a82142220652cf59' for validating against MitM-attacks.
Encrypted: YjE0ZzNyMHNwVm50MGswbQ==YsFRdKzCLuCk7Yg+U+S1CSgYBBR8dkZytORm8xwEDmD9WB1mpqC3XnSrB+wR3/KW
Decrypted: My super secret information.
Use HTTP header 'x-hmac: b2e63f216acde938a82142220652cf59' for validating against MitM-attacks.
Encrypted: YjE0ZzNyMHNwVm50MGswbQ==YsFRdKzCLuCk7Yg+U+S1CSgYBBR8dkZytORm8xwEDmD9WB1mpqC3XnSrB+wR3/KW
Decrypted: My super secret information.

$ node aes256cbc.js && php aes256cbc.php
Use HTTP header 'x-hmac: 73181744453d55eb6f81896ffd284cd8' for validating against MitM-attacks.
Encrypted: YjE0ZzNyMHNwVm50MGswbQ==YsFRdKzCLuCk7Yg+U+S1CTGik4Lv9PnWuEg5SiADJcdKX1to0LrNKmuCiYIweBAZ
Decrypted: My super secret information.
Use HTTP header 'x-hmac: 73181744453d55eb6f81896ffd284cd8' for validating against MitM-attacks.
Encrypted: YjE0ZzNyMHNwVm50MGswbQ==YsFRdKzCLuCk7Yg+U+S1CTGik4Lv9PnWuEg5SiADJcdKX1to0LrNKmuCiYIweBAZ
Decrypted: My super secret information.

$ node aes256cbc.js && php aes256cbc.php
Use HTTP header 'x-hmac: 5372ecca442d65f582866cf3b24cb2b6' for validating against MitM-attacks.
Encrypted: YjE0ZzNyMHNwVm50MGswbQ==YsFRdKzCLuCk7Yg+U+S1CYEITF6aozBNp7bA54qY0Ugg9v6ktwoH6nqRyatkFqy8
Decrypted: My super secret information.
Use HTTP header 'x-hmac: 5372ecca442d65f582866cf3b24cb2b6' for validating against MitM-attacks.
Encrypted: YjE0ZzNyMHNwVm50MGswbQ==YsFRdKzCLuCk7Yg+U+S1CYEITF6aozBNp7bA54qY0Ugg9v6ktwoH6nqRyatkFqy8
Decrypted: My super secret information.

Last but not least, if you don’t have openssl mod installed in php, you can use mcrypt instead with rijndael128 and pkcs7 padding (source) like this:

aes256cbc-mcrypt.php (v2)

<?php

function pkcs7pad($message) {
    $padding = 16 - (strlen($message) % 16);
    return $message . str_repeat(chr($padding), $padding);
}

function pkcs7unpad($message) {
    $padding = ord(substr($message, -1));  //get last char and transform it to Int
    return substr($message, 0, -$padding); //remove the last 'padding' string
}

function encrypt ($message, $method, $secret, &$hmac) {
    //$iv = substr(bin2hex(mcrypt_create_iv(mcrypt_get_iv_size($method, MCRYPT_MODE_CBC), MCRYPT_DEV_URANDOM)),0,16);    //use this in production
    $iv = substr($secret, 0, 16);    //using this for testing purposes (to have the same encryption IV in PHP and Node encryptors)
    $message = pkcs7pad($message);
    $encrypted = base64_encode($iv) . base64_encode(mcrypt_encrypt($method, $secret, $message, MCRYPT_MODE_CBC, $iv));
    $hmac = hash_hmac('md5', $encrypted, $secret);
    return $encrypted;
}

function decrypt ($encrypted, $method, $secret, $hmac) {
    if (hash_hmac('md5', $encrypted, $secret) == $hmac) {
        $iv = base64_decode(substr($encrypted, 0, 24));
        return pkcs7unpad(mcrypt_decrypt($method, $secret , base64_decode(substr($encrypted, 24)) , MCRYPT_MODE_CBC, $iv));
    }
}

function encryptWithTSValidation ($message, $method, $secret, &$hmac) {
    date_default_timezone_set('UTC');
    $message = substr(date('c'),0,19) . "$message";
    return encrypt($message, $method, $secret, $hmac);
}

function decryptWithTSValidation ($encrypted, $method, $secret, $hmac, $intervalThreshold) {
    $decrypted = decrypt($encrypted, $method, $secret, $hmac);
    $now = new DateTime();
    //echo "Decrypted: $decrypted\n";
    $msgDate = new DateTime(str_replace("T"," ",substr($decrypted,0,19)));
    if (($now->getTimestamp() - $msgDate->getTimestamp()) <= $intervalThreshold) {
        return substr($decrypted,19);
    }
}

$message = "My super secret information.";
$method = MCRYPT_RIJNDAEL_128;
$secret = "My32charPasswordAndInitVectorStr";  //must be 32 char length

//$encrypted = encrypt($message, $method, $secret, $hmac);
//$decrypted = decrypt($encrypted, $method, $secret, $hmac);

$encrypted = encryptWithTSValidation($message, $method, $secret, $hmac);
$decrypted = decryptWithTSValidation($encrypted, $method, $secret, $hmac, 60*60*12); //60*60m*12=12h

echo "Use HTTP header 'x-hmac: $hmac' for validating against MitM-attacks.\n";
echo "Encrypted: $encrypted\n";
echo "Decrypted: $decrypted\n";
?>

Ofcourse, some tests next:

$ php aes256cbc-mcrypt.php && node aes256cbc.js 
Use HTTP header 'x-hmac: 801282a9ed6b2d5bd2254140d7a17582' for validating against MitM-attacks.
Encrypted: YjE0ZzNyMHNwVm50MGswbQ==ipQ+Yah8xoF0C6yjCJr8v9IyatyGeNT2yebrpJZ5xH73H5fFcV1zhqhRGwM0ToGU
Decrypted: My super secret information.
Use HTTP header 'x-hmac: 801282a9ed6b2d5bd2254140d7a17582' for validating against MitM-attacks.
Encrypted: YjE0ZzNyMHNwVm50MGswbQ==ipQ+Yah8xoF0C6yjCJr8v9IyatyGeNT2yebrpJZ5xH73H5fFcV1zhqhRGwM0ToGU
Decrypted: My super secret information.
$ php aes256cbc-mcrypt.php && node aes256cbc.js 
Use HTTP header 'x-hmac: 0ab2bc83108e1e250f6ecd483cd65329' for validating against MitM-attacks.
Encrypted: YjE0ZzNyMHNwVm50MGswbQ==ipQ+Yah8xoF0C6yjCJr8v79P+j4YUl8ln8eu7FDqEdbxMe1Z7BvW8iVUN1qFCiHM
Decrypted: My super secret information.
Use HTTP header 'x-hmac: 0ab2bc83108e1e250f6ecd483cd65329' for validating against MitM-attacks.
Encrypted: YjE0ZzNyMHNwVm50MGswbQ==ipQ+Yah8xoF0C6yjCJr8v79P+j4YUl8ln8eu7FDqEdbxMe1Z7BvW8iVUN1qFCiHM
Decrypted: My super secret information.

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