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How does the crypto module work in Node.js

Theodore Kelechukwu Onyejiaku


The crypto module in Node.js provides functionalities such as encrypting, decrypting, and hashing any type of data in a Node.js application. In this shot, we will learn how to check if our Node.js application supports the crypto module.

Illustration of data encryption

Check crypto module availability

Below is the code that we can use to check if the crypto module is supported in our Node.js application.


// create a variable called crypto
let crypto;

// use the try-catch block
try {
  // import crypto if available
  crypto = require('crypto');
  console.log("crypto is enabled!!!")
  // log out the module
} catch (err) {
  // log out error
  console.log('crypto support is disabled!');
How to check if our application supports the crypto module


  • Line 2: We create a variable that will be instantiated using the crypto module.
  • Line 5: Using the try-catch block, we try to access the crypto module.
  • Line7: We import the module if available.
  • Line 11: We log the crypto module to the console (if available).
  • Line 12: We use the catch block to catch any errors or exceptions that the try block may have produced.

What can the crypto module do for us?

In general, here are some cool things that the crypto module can do for us!

  1. Cipher: This is a class of the crypto module that is responsible for encrypting our data. For instance, we can use this to encrypt passwords. It only takes an algorithm, a random number, and the data that we want to encrypt. The example below shows how to use cipher, followed by an explanation of the code:

// crypto module
const crypto = require("crypto");

// the algorithm we are using
const algorithm = "aes-256-cbc"; 

// generate 16 bytes of random data known as vector
const randBytes = crypto.randomBytes(16);

// sensitive data
const data = "my password";

// secret key generate 32 bytes of random data
const Securitykey = crypto.randomBytes(32);

// the cipher function
const cipher = crypto.createCipheriv(algorithm, Securitykey, randBytes);

// encrypt the message
// input encoding
// output encoding
let encryptedData = cipher.update(data, "utf-8", "hex");

encryptedData = encryptedData +"hex")
Encrypting data in NodeJS using crypto module

In the code above:

  • Line 2: We import the crypto module.
  • Line 5: We specify the algorithm we are using for encryption, namely aes-256-cbc.
  • Line 8: We create a random byte, also known as the vector.
  • Line 11: We enter the data that we want to protect.
  • Line 14: We create a security code made of 32 bytes that will be used for the encryption.
  • Line 17: We create a cipher function using the createCipheriv() method. It takes the algorithm, security key, and random bytes as parameters. Another method that we can use is createDecipher(). Unfortunately, however, it is deprecated.
  • Line 22: Using the update() method of the cipher, we encrypt the data in UFT-8 encoding and in a hexadecimal format.
  • Line 24: We call the final() method, which ends the encryption.
  • Line 25: We log the data in the encrypted format to the console.

2. Decipher: This is the opposite of cipher. It decrypts encrypted data.

3. Hash: With the crypto module, we can also create hashes. A hash cannot be converted back to its original form.

Other classes the crypto module uses include certificate, diffieHellman, ECDH, HMAC, Sign, and more.




Theodore Kelechukwu Onyejiaku

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