crappy implementation of gamespy's rc4 challenge algorithm in NodeJS

gamespyChallengeRC4.js

/*
   crappy implementation of gamespy's rc4 challenge algorithm in NodeJS
   basically just eyed from https://github.com/barronwaffles/dwc_network_server_emulator/blob/master/gamespy/gs_utility.py
   strkey = String of "secret key" used by client
   data = Buffer of challenge data sent by server
   return value = String of base64 encoded challenge response
   i only tested this once, it could probably be improved, idk if it works 100%
*/
function gamespyChallengeRC4(strkey, data) {
	key = Buffer.from(strkey);
	var S = Array.from(Array(0x100).keys());
	var j = 0;
	var i = 0;
	for (i = 0; i < 0x100; i++) {
		j = (j + S[i] + key[i % key.length]) & 0xff;
		var si = S[i];
		var sj = S[j];
		S[i] = sj;
		S[j] = si;
	}
	i = 0;
	j = 0;
	for (var h = 0; h < data.length; h++) {
		val = data[h];
		i = (i + 1 + val) & 0xff;
		j = (j + S[i]) & 0xff;
		var si = S[i];
		var sj = S[j];
		S[i] = sj;
		S[j] = si;
		data[h] ^= S[(S[i] + S[j]) & 0xff];
	}
	data[data.length - 1] = 0x00; // hacky idk
	return data.toString("base64");
}