Node.js · Module

node:crypto

The node:crypto module provides Node.js access to cryptographic operations including hashes, HMACs, encryption, decryption, signing, and verification. Its APIs wrap functionality supplied by OpenSSL.

Since: v0.1.94

How it works

Import the module with the node:crypto specifier, then use its APIs to create cryptographic objects such as hashes, HMACs, ciphers, decipher streams, signers, and verifiers. These objects consume data through update-style methods and produce results through operations such as digest, final, sign, or verify.

Syntax

import * as crypto from 'node:crypto';

Key points

The module groups common cryptographic primitives behind Node.js APIs backed by OpenSSL.
Modern ECMAScript modules can import crypto APIs using the node:crypto built-in-module specifier.
Use createHash() as the factory for producing hash objects.
getHashes() lets code inspect digest algorithms supported by the current runtime.

Common mistakes

A Node.js build may omit this module, in which case importing it or requiring it throws an error.
Create hash objects through the factory function rather than constructing Hash instances directly.

Example: Hash a string

import { createHash } from 'node:crypto';

const digest = createHash('sha256')
  .update('hello')
  .digest('hex');

console.log(digest);

Creates a SHA-256 hash of a string and prints its hexadecimal digest.

When to use it

Content integrity checks

Verify that an incoming payload matches a known digest before processing it.

Message authentication

Generate or validate keyed message authentication codes for trusted messages.

Application security operations

Encrypt, decrypt, sign, or verify data using supported cryptographic primitives.

Interview questions

QWhat is the purpose of the node:crypto module?

The node:crypto module exposes cryptographic functionality backed by wrappers around OpenSSL. Its documented areas include hashing, HMAC, encryption and decryption, signing, and signature verification.

Follow-up: How would you hash data incrementally? Create a hash with createHash(), pass chunks to hash.update(), then call hash.digest() to obtain the result.

QHow do you calculate a digest?

Use createHash(algorithm) to obtain a Hash instance. Feed data with update() and finalize it with digest(), optionally requesting an encoding such as hexadecimal.

Follow-up: What should be checked before selecting an algorithm? Use the documented supported-algorithm information rather than assuming every OpenSSL algorithm is available in the runtime.

QWhat happens if crypto support is disabled?

The module can be unavailable in a Node.js build. In that case, importing from node:crypto or calling require('node:crypto') throws an error, so applications should account for runtime support when necessary.

Follow-up: What is a practical way to detect this condition? Load the module during startup and handle the import or require failure before attempting cryptographic operations.

createHash()
createHmac()
Hash
Hmac
Cipher
Decipher
Sign
Verify

Source: Crypto. Checked 2026-10-15.