RangeError: Input buffers must have the same byte length

[alex996]

This library doesn't work with non-ASCII characters. Here's example code:

const tsse = require("tsse");

console.log("a".length, "ä".length); // 1 1
console.log(Buffer.from("a").length, Buffer.from("ä").length); // 1 2
console.log(tsse("a", "ä")); // RangeError

The problem is on this line:

if (hiddenStr.length !== inputStr.length) {

and these two lines:

const hiddenBuff = Buffer.from(hiddenStr);
const inputBuff = Buffer.from(inputStr);

This code works if both arguments are Buffers, because their length is the same as their byteLength, and Buffer.from simply creates a copy.

However, it doesn't work if the arguments are Strings. A string in JavaScript is encoded in UTF-16, so its length is the number of UTF-16 code units, rather than bytes. However, when you call Buffer.from(hiddenStr), the encoding defaults to utf8.

I think something like this would work better (I renamed hiddenStr and inputStr to hidden and input):

const hiddenLen = typeof hidden === "string" ? Buffer.byteLength(hidden) : hidden.length;
const inputLen = typeof input === "string" ? Buffer.byteLength(input) : input.length;

if (hiddenLen !== inputLen) {

Note how Buffer.byteLength(string) also defaults to utf8 encoding.

[simonepri]

Hi @alex996, thanks for opening an issue.

Could you please send a PR to fix this?
Thanks!