Different Outputs for AES Encryption using CryptoJS and AES Encryption in JavaScript

Question

Here is my solution to PHP, Ruby & Swift.

I faced issues when using CryptoJS on my test.

my code is like this

var data = "Hello World";
var key = "57119C07F45756AF6E81E662BE2CCE62";
var iv = "GsCJsm/uyxG7rBTgBMrSiA==";

var encryptedData = CryptoJS.AES.encrypt(data, 
    CryptoJS.enc.Hex.parse(key), {
        mode: CryptoJS.mode.CBC,
        padding: CryptoJS.pad.Pkcs7,
        iv: CryptoJS.enc.Base64.parse(iv) 
    }
);

console.log("encryptedData: " + encryptedData);

// var crypttext = encryptedData.toString();
var crypttext = "k4wX2Q9GHU4eU8Tf9pDu+w==";

var decryptedData = CryptoJS.AES.decrypt({
    ciphertext: CryptoJS.enc.Base64.parse(crypttext) 
}, CryptoJS.enc.Hex.parse(key), {
    mode: CryptoJS.mode.CBC,
    padding: CryptoJS.pad.Pkcs7,
    iv: CryptoJS.enc.Base64.parse(iv) 
});

console.log("decryptedData: " + decryptedData);

console.log result

encryptedData: 97SwKfGtNARERiSYyZxdAQ==

decryptedData:

Community · Accepted Answer · 2017-04-13 12:48:17Z

2

I've looked at your PHP code. You're using a 32 character key which is obviously Hex-encoded, but instead of decoding it to bytes, you're using the characters directly. Therefore the aes-256-cbc cipher is also wrong.

If you don't want to change your misleading PHP code, you can simply make the same mistake in CryptoJS: CryptoJS.enc.Utf8.parse(key) instead of CryptoJS.enc.Hex.parse(key).

Security considerations:

The IV must be unpredictable (read: random). Don't use a static IV, because that makes the cipher deterministic and therefore not semantically secure. An attacker who observes ciphertexts can determine when the same message prefix was sent before. The IV is not secret, so you can send it along with the ciphertext. Usually, it is simply prepended to the ciphertext and sliced off before decryption.

It is better to authenticate your ciphertexts so that attacks like a padding oracle attack are not possible. This can be done with authenticated modes like GCM or EAX, or with an encrypt-then-MAC scheme.

edited Apr 13, 2017 at 12:48

CommunityBot

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answered Aug 11, 2016 at 18:16

Artjom B.

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2 Comments

Jackyrx Over a year ago

Thanks a lot for the reply. <br/> As I am not really familiar with the encryption/ decryption stuff. So, I may make this mistakes.<br/> Anyway, let me try it later, see if it works.<br/> PS: Random IV would be used after the test of functions and before push to production environment.<br/>

Jackyrx Over a year ago

btw, i have tested on it. It works. Thanks first. I will enhance it later. Any advices? @Artjom B.

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