AES encryption using Php , javascript and vise versa

Question

I am doing client side encryption using javascript and server side using PHP. Both side we are using same key and IV.

Php Encryption :

$string='test data';

$output = '';
    $encrypt_method = 'AES-256-CBC';
    $secret_key     = 'secret key in hex';
    $secret_iv      = 'iv in hex';
    $key            = hash('sha256',$secret_key);

$output   = openssl_encrypt($string,$encrypt_method,$key,0,$initialization_vector);

//Encrypted text in php
$output   = base64_encode($output);

Javascript Encryption Code:

var key = 'secret key in hex';
key = CryptoJS.SHA256(key);            
var ivHex = CryptoJS.enc.Hex.parse(' IV in hex ');            
var options = { mode: CryptoJS.mode.CBC, padding: CryptoJS.pad.Pkcs7, iv:ivHex};
var obj='test data';
var encrypted = CryptoJS.AES.encrypt(obj,key ,options);
var encryptedBase64 = encrypted.toString();

//Encrypted text in javascript    
console.log(encryptedBase64);

Both are giving different output. Am I doing anything wrong?

Stick to openssl_encrypt(). Best method is AES-256-CTR and of course use IV with 16 chars. — halojoy
– halojoy, Commented Dec 30, 2017 at 9:22

Scott Arciszewski · Accepted Answer · 2017-12-30 18:06:49Z

1

$secret_iv is defined, but an undefined $initialization_vector is used in openssl_encrypt().
For the fourth argument, you don't want to pass 0, you want to pass OPENSSL_RAW_DATA (a constant).
You're passing hash('sha256', $secret_key) in PHP but using secret_key directly in Javascript.
- Note: Your key derivation (hash('sha256', $some_text_input)) is very weak. Consider PBKDF2-SHA256 instead.

Important: AES-CBC without an HMAC is vulnerable to padding-oracle attacks. You should always use authenticated encryption.

An example of secure encryption looks like this. Decryption is a little more involved.

answered Dec 30, 2017 at 18:06

Scott Arciszewski

34.3k17 gold badges94 silver badges212 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Luke Joshua Park Over a year ago

Good answer. To future readers, also note that as of PHP 7.1, AES in GCM mode is supported, which is likely a better fit for new work than CTR mode since it eliminates the need for an HMAC.

Collectives™ on Stack Overflow

AES encryption using Php , javascript and vise versa

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related