function Get-SP2013ProductKey {

$map=”BCDFGHJKMPQRTVWXY2346789″

$value = (get-itemproperty “HKLM:\SOFTWARE\Microsoft\Office\15.0\Registration\{90150000-110D-0000-1000-0000000FF1CE}”).digitalproductid[0x34..0x42]

$ProductKey = “”

for ($i = 24; $i -ge 0; $i–) {

$r = 0

for ($j = 14; $j -ge 0; $j–) {

$r = ($r * 256) -bxor $value[$j]

$value[$j] = [math]::Floor([double]($r/24))

$r = $r % 24

}

$ProductKey = $map[$r] + $ProductKey

if (($i % 5) -eq 0 -and $i -ne 0) {

$ProductKey = “-” + $ProductKey

}

}

$ProductKey

}

#Call the function

Get-SP2013ProductKey