PowerShell script to calculate current "ProductKey"

get-product-key.ps1

### "get-product-key.ps1":
### (updated from https://superuser.com/a/1367165)
###
### To allow this script to run, execute one of these in admin PS:
###
###   Set-ExecutionPolicy RemoteSigned -Scope CurrentUser
### or
###   Set-ExecutionPolicy RemoteSigned
###
### And then execute the following:
###
###   Import-Module .\get-product-key.ps1; Get-WindowsKey
###
### You should see something similar to this:
###
###   Computer     : .
###   Caption      : Microsoft Windows 7 Professional
###   CSDVersion   : Service Pack 1
###   OSArch       : 64-bit
###   BuildNumber  : 7601
###   RegisteredTo : somebody
###   ProductID    : 00000-OEM-9999999-99999
###   ProductKey   : 9Z9Z9-9Z9Z9-9Z9Z9-9Z9Z9-9Z9Z9
###
### The ProductKey will be shown last - as per above.

function Get-WindowsKey 
{
    param ($targets = ".")
    $hklm = 2147483650
    $regPath = "Software\Microsoft\Windows NT\CurrentVersion"
    $regValue = "DigitalProductId"
    Foreach ($target in $targets) {
        $productKey = $null
        $win32os = $null
        $wmi = [WMIClass]"\\$target\root\default:stdRegProv"
        $data = $wmi.GetBinaryValue($hklm,$regPath,$regValue)
        $binArray = ($data.uValue)[52..66]
        $charsArray = "B","C","D","F","G","H","J","K","M","P","Q","R","T","V","W","X","Y","2","3","4","6","7","8","9"
        ## decrypt base24 encoded binary data
        For ($i = 24; $i -ge 0; $i--) {
            $k = 0
            For ($j = 14; $j -ge 0; $j--) {
                $k = $k * 256 -bxor $binArray[$j]
                $binArray[$j] = [math]::truncate($k / 24)
                $k = $k % 24
            }
            $productKey = $charsArray[$k] + $productKey
            If (($i % 5 -eq 0) -and ($i -ne 0)) {
                $productKey = "-" + $productKey
            }
        }
        $win32os = Get-WmiObject Win32_OperatingSystem -computer $target
        $obj = New-Object Object
        $obj | Add-Member Noteproperty Computer -value $target
        $obj | Add-Member Noteproperty Caption -value $win32os.Caption
        $obj | Add-Member Noteproperty CSDVersion -value $win32os.CSDVersion
        $obj | Add-Member Noteproperty OSArch -value $win32os.OSArchitecture
        $obj | Add-Member Noteproperty BuildNumber -value $win32os.BuildNumber
        $obj | Add-Member Noteproperty RegisteredTo -value $win32os.RegisteredUser
        $obj | Add-Member Noteproperty ProductID -value $win32os.SerialNumber
        $obj | Add-Member Noteproperty ProductKey -value $productkey
        $obj
    }
}