mediumLow-Level Design

Explain how the 'crypto' module secures sensitive data in Node.js

Q: Explain how the 'crypto' module secures sensitive data in Node.js

**TL;DR.** The node:crypto module wraps OpenSSL to provide **hashing** (SHA-256), **HMAC**, **symmetric** encryption (AES), **asymmetric** keys (RSA/EC), **signing/verification**, and secure **random** bytes. Use it to protect data **at rest and in transit** — but for passwords use slow KDFs (pbkdf2/scrypt/argon2), not plain hashes. hash / HMAC AES (symmetric) RSA/EC <rect class='d-box' x='350' y='40' width='90' height='40' rx='8'/

765 views

Understand the problem

An introduction to cryptographic principles and hashing within Node.

cryptosecurityhashing

Attempt it yourself

Sketch your approach before reading the solution — that's what interviews test.

Stuck? AI Nudge Available

Get a conceptual hint to guide your logic without spoiling the final implementation.

Study the solution

The solution is waiting

Give it an honest attempt first — then compare your thinking with the full walkthrough.

Read the code

Authenticated AES-GCM encryption

import crypto from 'node:crypto';

function encrypt(plaintext, key /* 32 bytes */) {
  const iv = crypto.randomBytes(12);                 // unique per message
  const cipher = crypto.createCipheriv('aes-256-gcm', key, iv);
  const enc = Buffer.concat([cipher.update(plaintext, 'utf8'), cipher.final()]);
  return { iv, tag: cipher.getAuthTag(), data: enc }; // tag proves integrity
}

Join the discussion

Discussion (0)

No responses yet. Be the first to share what you think.

What does the events.once() helper do and how does it bridge EventEmitter and async/await?

Explain the differences between fork(), spawn(), and exec() in the child_process module.