Emulating C-style integer maths in javascript

ICG-algo.js

/* eslint no-console:0, func-names:0 */

// JS ints are signed, which isn't useful here. Unfortunately,
// this means << can flip the sign bit and give a negative
// number which throws everything off. Luckily, we know how to
// handle this. The below is an unsigned leftshift implementation.
const ls = (input, shift) => ((input << shift) >>> 1) * 2;

// Integer casts that drop overflowing data (Just like grandma used to make)
const u8 = i => (i << 24) >>> 24;
const u16 = i => (i << 16) >>> 16;
const u32 = i => i >>> 0;
// JS is kind enough to convert into 32bit ints for us when we use any bitwise operations

const compress = function compress(input, rounds) {
  const lu = ['0', '1', '2', '3', '4', '5', '6', '7',
    '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
    'I', 'J', 'K', 'L', 'M', 'N', 'P', 'Q', 'R', 'S',
    'T', 'U', 'V', 'W', 'X', 'Y', 'Z'];
  let num = input;

  const builder = (new Array(rounds)).fill(' ');
  let index;
  for (let i = 0; i < rounds; i += 1) {
    index = u32(num % 0x23);
    num = Math.floor(num / 0x23);
    builder[i] = lu[index];
  }
  return builder.join('');
};

const getHashCode = function getHashCode(host) {
  let num = u32(0x1505);
  let num2 = u32(0x1505);
  for (let i = 0; i < host.length; i += 1) {
    num = u32((ls(num, 5) + num) ^ host[i++].charCodeAt(0));
    if (i < host.length) {
      num2 = u32((ls(num2, 5) + num2) ^ host[i].charCodeAt(0));
    }
  }
  return u32(num + u32(num2 * 0x5d588b65));
};

const getAuth = function getAuth(hostname) {
  let loSID = getHashCode(hostname);
  let hiSID = u16(getHashCode(`${hostname}|`));
  const num1 = u32(loSID % 2);
  const num2 = u32(hiSID % 2);

  loSID = u32(ls(num2, 31) + (loSID >>> 1));
  hiSID = u32(ls(num1, 15) + (hiSID >>> 1));
  hiSID = u32(0x30000172 + ls(hiSID, 10));

  const a = u32(hiSID % 1024);
  const b = u16(hiSID >>> 26);
  const d = u32((ls(hiSID, 6) >>> 16));

  // Set this to fixed value for debugging purpoises. (sic)
  // const first = u16(0x1337);
  const first = u16(Math.floor((Math.random() * 65535)));
  const fourth = u16(loSID);
  const fifth = u16(loSID >>> 16);
  const second = u16(ls(b, 27) + ls(d, 10) + a);
  const third = u16((ls(b, 27) + ls(d, 10) + a) >>> 16);

  const buffer = new Array(12);
  buffer[1] = u8(first >>> 8);
  buffer[0] = u8(ls(buffer[1], 8) ^ first);
  buffer[3] = u8(second >>> 8);
  buffer[2] = u8(ls(buffer[3], 8) ^ second);
  buffer[5] = u8(third >>> 8);
  buffer[4] = u8(ls(buffer[5], 8) ^ third);
  buffer[7] = u8(fourth >>> 8);
  buffer[6] = u8(ls(buffer[7], 8) ^ fourth);
  buffer[9] = u8(fifth >>> 8);
  buffer[8] = u8(ls(buffer[9], 8) ^ fifth);
  buffer[10] = u8((first >>> 4) ^ 65535);
  buffer[11] = 0;

  let index;
  for (index = 0; index < 11; index += 1) {
    buffer[11] = u8(buffer[11] + buffer[index]);
  }

  for (index = 1; index < 6; index += 1) {
    const int = index * 2;
    buffer[int] = u8(buffer[int] ^ buffer[0]);
    buffer[int + 1] = u8(buffer[int + 1] ^ buffer[1]);
  }
  const buffera = (new Array(12)).fill(0);
  for (index = 0; index < 12; index += 1) {
    buffera[index] = u8(buffer[index] >>> 3);
    buffer[index] = u8(ls(buffer[index], 5));
  }
  buffer[0] = u8(buffer[0] + buffera[7]);
  buffer[1] = u8(buffer[1] + buffera[0]);
  buffer[2] = u8(buffer[2] + buffera[1]);
  buffer[3] = u8(buffer[3] + buffera[2]);
  buffer[4] = u8(buffer[4] + buffera[11]);
  buffer[5] = u8(buffer[5] + buffera[4]);
  buffer[6] = u8(buffer[6] + buffera[5]);
  buffer[7] = u8(buffer[7] + buffera[6]);
  buffer[8] = u8(buffer[8] + buffera[3]);
  buffer[9] = u8(buffer[9] + buffera[8]);
  buffer[10] = u8(buffer[10] + buffera[9]);
  buffer[11] = u8(buffer[11] + buffera[10]);
  const auth = `${
    compress(u32(
    ls(buffer[3], 24) +
    ls(buffer[2], 16) +
    ls(buffer[1], 8) +
    buffer[0]), 7)
  }-${
    compress(u32(
    ls(buffer[7], 24) +
    ls(buffer[6], 16) +
    ls(buffer[5], 8) +
    buffer[4]), 7)
  }-${
    compress(u32(
    ls(buffer[11], 24) +
    ls(buffer[10], 16) +
    ls(buffer[9], 8) +
    buffer[8]), 7)
  }`;
  const sid = `${compress(hiSID, 7)}-${compress(loSID, 7)}`;
  return {auth, sid};
};

const keygen = function keygen(hostname) {
  const major = [
    1048335, 1048334, 1048333, 1048332, 1048331, 1048330, 1048329, 1048328,
    1048327, 1048326, 1048325, 1048324, 1048323, 1048322, 1048321, 1048320
  ][Math.floor(Math.random() * 16)];
  return `Serial:${
    (ls(major, 1) ^ major)
  }\nProduct Code: ${
    compress(major, 5)
  }-XA${
    compress(major << 1, 5)
  }\nMachine Name: ${
    hostname
  }\nAuth Code: ${
    getAuth(hostname).auth
  }\n`;
};

const hostname = 'Tilt'.toUpperCase();
console.log(keygen(hostname));