NodeJS - URSA : Asymmetric Cryptology With Signature

nodeJs.ursa.asymmetricCryptologyWithSignature.js

// How to send message from A user to B user, encrypting it (asymetric cryptology) and sign it

var ursa      = require('ursa')
  , message   = 'Hello world!'
  , encoding  = 'base64'
  , buffer    = new Buffer(message, 'ascii')

// Creating a pair of keys of user A (a private key contains both keys...)
console.log('Generating Keys Pair of user A...')
var keysA = ursa.generatePrivateKey()
console.log('Making public key of A...')
var pubPemA = keysA.toPublicPem(encoding)
var pubA = ursa.createPublicKey(pubPemA, encoding)
console.log('Making private key of A...')
var prvPemA = keysA.toPrivatePem(encoding)
var prvA = ursa.createPrivateKey(prvPemA, '', encoding)

// Creating a pair of keys of user B
console.log('\nGenerating Keys Pair of user B...')
var keysB = ursa.generatePrivateKey()
console.log('Making public key of B...')
var pubPemB = keysB.toPublicPem(encoding)
var pubB = ursa.createPublicKey(pubPemB, encoding)
console.log('Making private key of B...\n')
var prvPemB = keysB.toPrivatePem(encoding)
var prvB = ursa.createPrivateKey(prvPemB, '', encoding)

// User A sign message with his private key and encript with public key of B user
var algorithm = 'md5'
  , signature = prvA.hashAndSign(algorithm, buffer, encoding, encoding)
  , encryptedMessage = pubB.encrypt(buffer, encoding)

// User B verify signature with public key of A and decript with his private key
var decryptedMessage = prvB.decrypt(encryptedMessage, encoding)
  , buffer2 = new Buffer(decryptedMessage, 'ascii')
  , isValid = pubA.hashAndVerify(algorithm, buffer2, signature, encoding)

console.log("Original Message to send from A to B: " + message)
console.log("Message after encrypt and decrypt: " + decryptedMessage)
console.log("Signature match? " + isValid)