Byte array to hexadecimal and back again in JavaScript

I can generate a byte array with

var myByteArray = window.crypto.getRandomValues(new Uint8Array(16))

and I get

181,143,16,173,231,56,63,149,181,185,224,124,84,230,123,36

I can then turn this into a string with

cryptoHelpers.convertByteArrayToString(myByteArray);

and i get

µç8?µ¹à|Tæ{$

But what I really want is a 128 bit hexadecimal like...

6a3e52297b2e593f4d506f7164

And I want to be able to go back from hexadecimal to a byte array.

Is there a copy and paste function or library to make this magic happen?

Will-In-China

Posted 2017-04-12T03:04:01.503

Reputation: 408

3I'm voting to close this question as off-topic because it is unrelated to Bitcoin. – Anonymous – 2018-10-12T11:25:11.923

You should ask this question on Stackoverflow, however search first. I'm positive the answer will already exist. – Jestin – 2018-10-17T18:15:19.680

I'm voting to close this question as off-topic because, the question, as written, does not appear related to bitcoin. Perhaps there is a relation, but if so, it should be made explicit. – dbkeys – 2018-10-20T09:53:53.403

Answers

Here's something you can copy-paste in.

byteArray = new Uint8Array([181,143,16,173,231,56,63,149,181,185,224,124,84,230,123,36]);
function toHexString(byteArray) {
  return Array.prototype.map.call(byteArray, function(byte) {
    return ('0' + (byte & 0xFF).toString(16)).slice(-2);
  }).join('');
}
function toByteArray(hexString) {
  var result = [];
  for (var i = 0; i < hexString.length; i += 2) {
    result.push(parseInt(hexString.substr(i, 2), 16));
  }
  return result;
}
hexString = toHexString(byteArray);
byteArray = toByteArray(hexString);

From here/here.

Nick ODell

Posted 2017-04-12T03:04:01.503

Reputation: 26 536

Using the above I'm getting a string that is not 128bits 289332005600940420022031 if I console log myByteArray i get an array buffer like "Uint8Array(16) [181, 143, 16, 173, 231, 56, 63, 149, 181, 185, 224, 124, 84, 230, 123, 36]" how do i convert this to an array? – Will-In-China – 2017-04-12T04:12:05.420

@Will-In-China See edit. – Nick ODell – 2017-04-12T04:19:41.583

toByteArray get wrong values when hex-string contains an odd number of characters: "fff", "1AB" – Geograph – 2018-04-12T15:55:04.920

2@Geograph since each byte is 2 hex digits, this is expected behaviour - a hex string with an odd number of digits is in invalid hex string. – david.barkhuizen – 2018-10-10T10:53:57.343