/dev/urandom

[davalapar]

const fs = require('fs');

const urandom = (length) => new Promise((resolve) => {
  const stream = fs.createReadStream('/dev/urandom');
  stream.on('data', (data) => { // emits 65536-length buffer
    stream.destroy();
    resolve(data.slice(0, length));
  });
});

urandom(32).then(console.log).catch(console.error);

• 16 bytes = 128 bits
• 32 bytes = 256 bits
• typecheck: os, for windows crypto.randomBytes must be alternative
• typecheck: length parameter
• asymmetric signatures: ed25519
• password handling: scrypt
• random ids: 256-bit from /dev/urandom
• https://latacora.micro.blog/2018/04/03/cryptographic-right-answers.html

[davalapar]

async

const filehandle = fsPromises.open('/dev/urandom');
const urandom = async (length) => {
  const buffer = Buffer.alloc(length);
  await filehandle.read(buffer, 0, length, 0);
  return buffer;
};
const close = () => filehandle.close();

sync

const fd = fs.openSync('/dev/urandom');
const urandom = (length) => {
  const buffer = Buffer.alloc(length);
  fs.readSync(fd, buffer, 0, 32, 0);
  return buffer;
};
const close = () => fs.closeSync(fd);
urandom(32);

• initialize with buffer length
• overwrite buffer
• slice or copy the buffer
• parts: setup / instantiate, generate, teardown

[davalapar]

https://www.namecheap.com/security/2fa-two-factor-authentication/

[davalapar]

https://nodejs.org/dist/latest-v12.x/docs/api/crypto.html#crypto_crypto_randombytes_size_callback