Crypto with Express

Question

I have one problem, with crypto package from npm.

I wan't to to send encrypted string to server to decrypt with express router params.

But there is a big problem, if i enter invalid string, server gives me this error:

TypeError: Bad input string
at Decipher.update (crypto.js:144:26)
at decrypt (APPDIRECTORY\encryption.js:17:22)
at app.get (APPDIRECTORY\encryption.js:35:17)
at Layer.handle [as handle_request] (APPDIRECTORY\node_modules\express\lib\router\layer.js:95:5)
at next (APPDIRECTORY\node_modules\express\lib\router\route.js:137:13)
at Route.dispatch (APPDIRECTORY\node_modules\express\lib\router\route.js:112:3)
at Layer.handle [as handle_request] (APPDIRECTORY\node_modules\express\lib\router\layer.js:95:5)
at APPDIRECTORY\node_modules\express\lib\router\index.js:281:22
at param (APPDIRECTORY\node_modules\express\lib\router\index.js:354:14)
at param (APPDIRECTORY\node_modules\express\lib\router\index.js:365:14)

I just wan't to know, how to disable this error, and enter my own error!

Thanks!

EDIT:

const express = require('express')
const app = express();

var crypto = require('crypto'),
    algorithm = 'aes-256-ctr',
    password = 'd6F3Efeq';

function encrypt(text){
  var cipher = crypto.createCipher(algorithm,password)
  var crypted = cipher.update(text,'utf8','hex')
  crypted += cipher.final('hex');
  return crypted;
}

function decrypt(text){
  var decipher = crypto.createDecipher(algorithm,password)
  var dec = decipher.update(text,'hex','utf8')
  dec += decipher.final('utf8');
  return dec;
}


app.get('/decrypt/:string', (request, response) => {

  let string = request.params.string;
  response.send(decrypt(string));

})

app.listen(3030, (request, response) => {
  console.log("Server started succesfully!")
})

If string is not aes-256-ctr format, i got errors. So is there someway to validate string if string is aes-256-ctr format?

Answer 1

You just need try-catch:

function decrypt(text){
  try {
    var decipher = crypto.createDecipher(algorithm,password)
    var dec = decipher.update(text,'hex','utf8')
    dec += decipher.final('utf8');
    return { result: dec };
  } catch(err) {
    return { error: 'INVALID_ENCRYPTED_TEXT' };
  }
}


app.get('/decrypt/:string', (request, response) => {
  let string = request.params.string;
  const dec = decrypt(string);
  if (dec.error) {
    response.status(400).end();
  } else {
    response.send(dec.result);
  }
});