Node: Ciphertext can be decrypted when using array as password

[softlore]

Issuetype: bug
Version: v6.14.0
Platform: Linux 4.4.0-116-generic ~14.04.1-Ubuntu SMP x86_64 GNU/Linux
Subsystem: crypto

Hi, I am using crypto module for encryption and decryption.

const { pbkdf2, createCipheriv } = require('crypto');

const encryptData = (plainText, password) => new Promise((resolve, reject) => { 
    const salt = randomBytes(32);
    const iv = randomBytes(16);    

    pbkdf2(password, salt, 100000, 32, 'sha512', (error, derivedKey) => {
        if (error) {
            console.log(error);
            reject(error);
        }
        else {
            let encrypted = '';
            const cipher = createCipheriv('aes-256-ctr', derivedKey, iv);
            encrypted += cipher.update(plainText, 'utf8', 'hex');
            encrypted += cipher.final('hex');
            const data = {
                cipherText: encrypted,
                salt: salt.toString('hex'),
                iv: iv.toString('hex')
            };
            resolve(data);            
        }
    });
});

const decryptData = (cipherText, password, salt, iv) => new Promise((resolve, reject) => {
    const _salt = Buffer.from(salt, 'hex');
    const _iv = Buffer.from(iv, 'hex');
    pbkdf2(password, _salt, 100000, 32, 'sha512', (error, derivedKey) => {
        if (error) {
            reject(error);
        }
        else {
            let decrypted = '';
            const decipher = createCipheriv('aes-256-ctr', derivedKey, _iv);
            decrypted += decipher.update(cipherText, 'hex', 'utf8');
            decrypted += decipher.final('utf8');
            resolve(decrypted);
        }
    });
});

Data that is encrypted: "Hello World"

I think my decryption code is broken in 4th step.

1. If I use "LOCKIT" as password to encrypt the above string and use the same password to decrypt the cipherText, I can get Hello World back.
2. If I use a different password "IAMSTEALINGIT",I am getting an error invalid encoded string.
3. If an array variable to passed as password ["LOCKIT"], I can encrypt and decrypt the data.
4. The data is encrypted using ["LOCKIT"]. If I try to decrypt the data using [" "], ["SNEAKYTHIEF"], ["ONEPUNCH"] as passwords, I am getting Hello World as the decrypted data.

I don't know whether my code is correct or not. Can someone help me with this issue?

[tniessen]

Could you please post code showing how you invoke these functions? Does this reproduce in recent LTS releases?

[mscdex]

Is it possible array passwords are being converted to a (constant) string (e.g. '[object Array]'), which might explain why any array value will work?

[softlore]

@tniessen I am building a react project using webpack. I am using the functions as follows:

import { encryptData, decryptData } from './crypto-methods';

// both the functions are in different components. 
// I have just nested functions to show how I am invoking them
// I am actually saving the data returned by encrypData function in localStorage,
// Later in a different component, I am getting the values from localStorage and decrypting it
encryptData(this.state.message, this.state.password).then(data => {
    console.log(`Encrypted Data: ${JSON.stringify(data)}`); // this goes to localStorage
    decryptData(data.cipherText, this.state.password, data.salt, data.iv).then(data => console.log(data));
});

I made a mistake while updating the textbox value,

handleTextbox_onChange(event){
    this.setState({
         [event.target.name]: [event.target.value]
    })
}

As you can see, instead of passing event.target.value, I was passing [event.target.value]. So when I entered different passwords, I could decrypt the cipherText.

[tniessen]

@gmk292 Which CJS crypto module are using in your project? The officially maintained crypto module does not work as part of a client-side JS application.

[softlore]

@tniessen I am using the nodejs crypto module. You are right.

I just tested the same in node console. When array is used I am getting the following error.

UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 2): TypeError: Pass phrase must be a buffer

Sorry for raising an issue, without checking this first.:bow:

[tniessen]

To summarize: The problem occurs when passing an array as the "passphrase" parameter to crypto.pbkdf2 in node 6.14.0. Is that correct?

The function should throw an error:

> process.version
'v6.14.0'
> crypto.pbkdf2([ 'LOCKIT' ], crypto.randomBytes(32), 100000, 32, 'sha512', (err, key) => console.log(key));
TypeError: Pass phrase must be a buffer
    at TypeError (native)
    at pbkdf2 (crypto.js:622:20)
    at Object.exports.pbkdf2 (crypto.js:604:10)
    at repl:1:8
    at sigintHandlersWrap (vm.js:22:35)
    at sigintHandlersWrap (vm.js:73:12)
    at ContextifyScript.Script.runInThisContext (vm.js:21:12)
    at REPLServer.defaultEval (repl.js:340:29)
    at bound (domain.js:280:14)
    at REPLServer.runBound [as eval] (domain.js:293:12)

I am using the nodejs crypto module.

So you are using the nodejs crypto modulo on the client-side from within a browser or is the code being executed by a Node.js server application?

[softlore]

@tniessen I am using webpack-dev-server for the react application. It is pure client-side app. There are no services in the backend that do the encryption/decryption for the app

[tniessen]

@gmk292 I didn't notice that you already edited https://github.com/nodejs/node/issues/19699#issuecomment-377533195, sorry. As suspected, this is not a problem with Node.js but with the module used within webpack. Please open an issue there.

[softlore]

@tniessen Thanks for your help :smile:

[tniessen]

No problem, always glad to be of assistance 😃

[ChALkeR]

Juding from the comments above, this looks like it may be a noticeable security footgun in whatever npm package that is responsible for this.

Encrypt functions absolutely mustn't coerce invalid values in passwords to constant strings.

[tniessen]

@ChALkeR Should be fixed in https://github.com/crypto-browserify/pbkdf2/pull/77.

[ChALkeR]

@tniessen Thanks for finding that module and fixing it!