find Windows Product Key

convertToKey.rb

require 'win32ole'

# original vbscript is: 
# https://support.lenovo.com/mx/ja/solutions/ht500032
# 
def convertToKey(key)
  keyOffset = 52
  i = 28
  chars = "BCDFGHJKMPQRTVWXY2346789"
  keyOutput = ""
  while i >= 0
    cur = 0
    x = 14

    while x >= 0
      cur = cur * 256
      cur = key[x + keyOffset] + cur
      key[x + keyOffset] = (cur / 24) & 255
      cur %= 24
      x -= 1
    end
    i -= 1
    keyOutput = chars[cur] + keyOutput
    if (((29 - i) % 6) == 0) && (i != -1) then
      i -= 1
      keyOutput = "-" + keyOutput
    end
  end
  keyOutput
end 

wsh = WIN32OLE.new('WScript.Shell')
value = wsh.RegRead 'HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\DigitalProductId'

out = convertToKey(value)
puts out