Node JS crypto "Bad input string"

Question

Want to decrypt a string from file.

But when i use nodejs decipher on the string from fs, it gives the error "Bad input string"

var fs = require('fs');
var crypto = require('crypto');

function decrypt(text){
  var decipher = crypto.createDecipher('aes-256-ctr', 'password')
  var dec = decipher.update(text,'hex','utf8')
  dec += decipher.final('utf8');
  return dec;
}

fs.readFile('./file.json', 'utf8', function (err,data) {
  if (err) return console.log(err);
  console.log(decrypt(data));
});

tried just making a string like this it works

var stringInFile= "encryptedString";
console.log(decrypt(stringInFile));

Tho console.log(data) from fs also gives 'encryptedString'

score 6 · Accepted Answer · answered Jun 15 '17 at 19:59

The problem with your code is NOTHING. The problem is the string that you're trying to decrypt. The string that you want to decrypt can't be any string. It must be a string generated from a similar encrypt function.

var crypto = require('crypto');
encrypt = function(text, passPhrase){
    var cipher = crypto.createCipher('AES-128-CBC-HMAC-SHA1', passPhrase);
    var crypted = cipher.update(text,'utf8','hex');
    crypted += cipher.final('hex');
    return crypted;
}

decrypt = function(text, passPhrase){
    var decipher = crypto.createDecipher('AES-128-CBC-HMAC-SHA1', passPhrase)
    var dec = decipher.update(text,'hex','utf8')
    dec += decipher.final('utf8');
    return dec;
}

console.log(decrypt(encrypt("Hello", "123"), "123"));

For example, this code works perfectly fine with no errors.

Hope it helps.

it is, and it works if i just decrypt it as a variable like you do... but it dosent work when string is loaded from a file.. — Stweet, Jun 16 '17 at 06:02
hmm never mind, working on some test looks like the string as you said — Stweet, Jun 16 '17 at 06:21
it was the file format ^^ it was utf8 with bom should have been without — Stweet, Jun 16 '17 at 06:29

Node JS crypto "Bad input string"

1 Answers1