Proposing to have `flush()` method

_privKey and _pubKey are always accessible that’s make me uncomfortable. I’m propose to have this one.

Wallet.prototype.flush = function () {
  assert(Buffer.isBuffer(this._privKey), 'Private key should be an instance of Buffer')
  this._privKey.fill(0x00);
  assert(Buffer.isBuffer(this._pubKey), 'Public key should be an instance of Buffer')
  this._pubKey.fill(0x00);
}

[alcuadrado]

IMO having such a method would give a false sense of security to the users of this library. It’s not easy to be sure that every copy of the key was erased, especially when the private key is used by external libraries.

[chiro-hiro]

I’m not fully sure what problem this is solving, since the key is not cleared from memory.

I’ve tried to do some experiments and observe result. We can’t remove the value from the memory easily even using delete but we can overwrite it.

const readline = require('readline');
let mem = Buffer.from('112233445566778899aabbccddeeff', 'hex');

readline.emitKeypressEvents(process.stdin);

process.stdin.on('keypress', (str, key) => {

  if (str === '\u0003' || (key.name === 'c' && key.ctrl)) {
    process.exit();
  }

  let fillValue = ((Math.random() * 0xff) | 0) >>> 0;
  console.log('Fill buffer with:', fillValue.toString(16));
  mem.fill(fillValue)

});