Get Windows Product Key from PowerShell

Get Windows Product Key from PowerShell.ps1

# Derived from WinProdKeyFinder
# https://github.com/mrpeardotnet/WinProdKeyFinder
$digitalProductId = (Get-ItemProperty -Path 'HKLM:\Software\Microsoft\Windows NT\CurrentVersion').DigitalProductId

# First byte appears to be length
if ($digitalProductId[0] -ne $digitalProductId.Length) {
    throw 'Invalid length.'
}

$ProductId = [Text.Encoding]::UTF8.GetString($digitalProductId[8..30])
$Sku = [Text.Encoding]::UTF8.GetString($digitalProductId[36..48])

$key = $null
$keyOffset = 52
$isWin8 = [math]::truncate($digitalProductId[66] / 6) -band 1
$digitalProductId[66] = ($digitalProductId[66] -band 0xf7) -bor (($isWin8 -band 2) * 4)

# decrypt base24 encoded binary data
$digits = 'BCDFGHJKMPQRTVWXY2346789'
$last = 0
For ($i = 24; $i -ge 0; $i--) {
    $current = 0
    For ($j = 14; $j -ge 0; $j--) {
        $current = $current * 256
        $current += $digitalProductId[$keyOffset + $j]
        $digitalProductId[$keyOffset + $j] = [math]::truncate($current / 24)
        $current = $current % 24
        $last = $current
    }
    $key = $digits[$current] + $key
}
$key = $key.Substring(1, $last) + 'N' + $key.Substring($last + 1, $key.Length - ($last + 1))
$key = $key.Substring(0, 5) + '-' + $key.Substring(5, 5) + '-' + $key.Substring(10, 5) + '-' + $key.Substring(15, 5) + '-' + $key.Substring(20, 5)

$cv = Get-ItemProperty -Path 'HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion'
$win32os = Get-WmiObject Win32_OperatingSystem

[PSCustomObject]@{
    Caption         = $win32os.Caption
    Version         = '{0} (OS Build {1}.{2})' -f $cv.DisplayVersion, $cv.CurrentBuild, $cv.UBR
    OSArch          = $win32os.OSArchitecture

    RegisteredOwner = $cv.RegisteredOwner

    ProductID       = $ProductId
    Sku             = $Sku

    ProductKey      = $key
}