Cryptography in Javascript

7 ways to use cryptography in javascript

1- hashing

const { createHash } = require('crypto');

// Create a string hash

function hash(str) {
    return createHash('sha256').update(str).digest('hex');
}

// Compare two hashed passwords

let password = 'hi-mom!';
const hash1 = hash(password);
console.log(hash1)

/// ... some time later

password = 'hi-mom';
const hash2 = hash(password);
const match = hash1 === hash2;

console.log(match ? '✔️  good password' : '❌  password does not match');

2- Salt

const { scryptSync, randomBytes, timingSafeEqual } = require('crypto');

function signup(email, password) {
    const salt = randomBytes(16).toString('hex');
    const hashedPassword = scryptSync(password, salt, 64).toString('hex');

    const user = { email, password: `${salt}:${hashedPassword}` }

    users.push(user);

    return user
}

function login(email, password) {
    const user = users.find(v => v.email === email);

    const [salt, key] = user.password.split(':');
    const hashedBuffer = scryptSync(password, salt, 64);

    const keyBuffer = Buffer.from(key, 'hex');
    const match = timingSafeEqual(hashedBuffer, keyBuffer);

    if (match) {
        return 'login success!'
    } else {
        return 'login fail!'
    }
}

const users = [];

const user = signup('[e-mail]', 'pa$$word');

console.log(user)

const result = login('[e-mail]', 'password')

console.log(result)

3- HMAC

const { createHmac } = require('crypto');

const password = 'super-secret!';
const message = '🎃 hello jack'

const hmac = createHmac('sha256', password).update(message).digest('hex');

console.log(hmac)

4- Symmetric Encryption

const { createCipheriv, randomBytes, createDecipheriv } = require('crypto');

/// Cipher

const message = 'i like turtles';
const key = randomBytes(32);
const iv = randomBytes(16);

const cipher = createCipheriv('aes256', key, iv);

/// Encrypt

const encryptedMessage = cipher.update(message, 'utf8', 'hex') + cipher.final('hex');
console.log(`Encrypted: ${encryptedMessage}`);

/// Decrypt

const decipher = createDecipheriv('aes256', key, iv);
const decryptedMessage = decipher.update(encryptedMessage, 'hex', 'utf-8') + decipher.final('utf8');
console.log(`Deciphered: ${decryptedMessage.toString('utf-8')}`);

5- Keypairs

const { generateKeyPairSync } = require('crypto');

const { privateKey, publicKey } = generateKeyPairSync('rsa', {
  modulusLength: 2048, // the length of your key in bits
  publicKeyEncoding: {
    type: 'spki', // recommended to be 'spki' by the Node.js docs
    format: 'pem',
  },
  privateKeyEncoding: {
    type: 'pkcs8', // recommended to be 'pkcs8' by the Node.js docs
    format: 'pem',
  },
});

console.log(publicKey);
console.log(privateKey);

6- Asymmetric Encryption

const {  publicEncrypt, privateDecrypt } = require('crypto');
const { publicKey, privateKey } = require('./keypair');


const encryptedData = publicEncrypt(
    publicKey,
    Buffer.from(secretMessage)
  );


console.log(encryptedData.toString('hex'))


const decryptedData = privateDecrypt(
    privateKey,
    encryptedData
);

console.log(decryptedData.toString('utf-8'));

7- signing

const { createSign, createVerify } = require('crypto');
const { publicKey, privateKey } = require('./keypair');

const data = 'this data must be signed';

/// SIGN

const signer = createSign('rsa-sha256');

signer.update(data);

const siguature = signer.sign(privateKey, 'hex');

console.log(siguature);

/// VERIFY

const verifier = createVerify('rsa-sha256');

verifier.update(data);

const isVerified = verifier.verify(publicKey, siguature, 'hex');

console.log(isVerified);