By Vishal Basumatary in javascript — Mar 25, 2023

nodejs createcipheriv invalid key length

NodeJS CreateCipheriv Invalid Key Length

If you are working with NodeJS and trying to use the CreateCipheriv function, you may encounter an error message that says "Invalid key length". This can be frustrating, especially if you are new to NodeJS and don't know how to solve the issue. In this post, I will explain what this error means and provide some solutions to fix it.

What does "Invalid key length" mean?

The "Invalid key length" error message means that the length of the key you are trying to use is not valid. In order to use the CreateCipheriv function, you need to pass a key of a certain length. Depending on the encryption algorithm you are using, the key length can vary.

How to fix "Invalid key length" error?

There are a few ways you can fix the "Invalid key length" error:

Use a valid key length: You need to make sure that the key you are passing to CreateCipheriv is of a valid length for the encryption algorithm you are using. For example, if you are using AES-256, you need to pass a key that is 256 bits (32 bytes) long.
Pad the key: If your key is not of a valid length, you can pad it with zeros or random bytes to make it the correct length. However, be careful when doing this as it can weaken the security of your encryption.
Use a key derivation function: Another solution is to use a key derivation function such as PBKDF2 or bcrypt. These functions generate a key of the correct length based on a password that you provide. This way, you don't have to worry about the key length yourself.

Code examples

Here are some code examples to illustrate the solutions mentioned above:

Use a valid key length

const crypto = require('crypto');

const algorithm = 'aes-256-cbc';
const key = crypto.randomBytes(32); // 256-bit key
const iv = crypto.randomBytes(16); // 128-bit IV

const cipher = crypto.createCipheriv(algorithm, key, iv);

// ...

Pad the key

const crypto = require('crypto');

const algorithm = 'aes-256-cbc';
let key = 'mykey';

// Pad the key with zeros to make it 256 bits long
while (key.length < 32) {
  key += '\0';
}

const iv = crypto.randomBytes(16); // 128-bit IV

const cipher = crypto.createCipheriv(algorithm, key, iv);

// ...

Use a key derivation function

const crypto = require('crypto');
const pbkdf2 = require('pbkdf2');

const algorithm = 'aes-256-cbc';
const password = 'mypassword';
const salt = crypto.randomBytes(16);
const iterations = 100000;
const keyLength = 32;

const derivedKey = pbkdf2.pbkdf2Sync(password, salt, iterations, keyLength, 'sha256');

const iv = crypto.randomBytes(16); // 128-bit IV

const cipher = crypto.createCipheriv(algorithm, derivedKey, iv);

// ...