Node.js Crypto Module

What is the Crypto Module?

The Crypto module is a built - in Node.js module that provides cryptographic functionality including:
Hash functions (SHA - 256, SHA - 512, etc.)
HMAC (Hash - based Message Authentication Code)

Digital signatures and verification

Secure random number generation

The Crypto module wraps the OpenSSL library, providing access to well - established and tested cryptographic algorithms.

User authentication and password storage

Secure data transmission

File encryption and decryption

Secure communication channels

Getting Started with Crypto

Basic Hashing Example

const crypto = require('crypto');
// Create a SHA-256 hash of a string const hash = crypto.createHash('sha256').update('Hello, Node.js!').digest('hex');
console.log('SHA-256 Hash:', hash);

Installing the Crypto Module

const crypto = require('crypto');

Hash Functions

Hashing is a one - way transformation of data into a fixed - length string of characters.

Deterministic:

Same input always produces the same output

Fixed Length:

One-Way:

Extremely difficult to reverse the process

Avalanche Effect:

Common use cases include:

Password storage

Data integrity verification

Digital signatures

Creating a Hash const crypto = require('crypto');
// Create a hash object const hash = crypto.createHash('sha256');
// Update the hash with data hash.update('Hello, World!');
// Get the digest in hexadecimal format const digest = hash.digest('hex');
console.log(digest);

In this example:

Common Hash Algorithms const crypto = require('crypto');
const data = 'Hello, World!';

// MD5 (not recommended for security - critical applications)

const md5 = crypto.createHash('md5').update(data).digest('hex');
console.log('MD5:', md5);

// SHA - 1 (not recommended for security - critical applications)

const sha1 = crypto.createHash('sha1').update(data).digest('hex');
console.log('SHA-1:', sha1);
// SHA-256 const sha256 = crypto.createHash('sha256').update(data).digest('hex');
console.log('SHA-256:', sha256);
// SHA-512 const sha512 = crypto.createHash('sha512').update(data).digest('hex');
console.log('SHA-512:', sha512);

Warning:

MD5 and SHA - 1 are considered cryptographically weak and should not be used for security - critical applications.
Use SHA - 256, SHA - 384, or SHA - 512 instead.

Password Security

Never store passwords in plain text or with simple hashes like MD5 or SHA - 1.
These can be easily cracked using rainbow tables or brute - force attacks.