Generates the QuickXorHash value of a local file.

Get-QuickXorHash.ps1

# Credit belongs to https://mgwdevcom.wordpress.com/2025/06/09/verifying-sharepoint-file-integrity-with-quickxorhash-in-powershell/
# made small updates to support PowerShell 5.1 

function Get-QuickXorHash  
{
    param 
    (
        [Parameter(Mandatory = $true)]
        [string]
        $FilePath
    )

    $BitsInLastCell = 32
    $Shift = 11
    $Threshold = 600
    $WidthInBits = 160

    $data = @(0..2 | ForEach-Object { [UInt64]0 })
    $lengthSoFar = 0
    $shiftSoFar = 0

    $buffer = [System.IO.File]::ReadAllBytes($FilePath)
    $lengthSoFar = $buffer.Length

    $ibStart = 0
    $cbSize = $buffer.Length

    $currentShift = $shiftSoFar
    $vectorArrayIndex = [math]::Floor($currentShift / 64)
    $vectorOffset = $currentShift % 64
    $iterations = [math]::Min($cbSize, $WidthInBits)

    for ($i = 0; $i -lt $iterations; $i++) 
    {
        $isLastCell = $vectorArrayIndex -eq ($data.Length - 1)
        
        # $bitsInVectorCell = $isLastCell ? $BitsInLastCell : 64
        $bitsInVectorCell = if( $isLastCell )
        {
            $BitsInLastCell
        }
        else
        {
            64
        }
        
        if ($vectorOffset -le ($bitsInVectorCell - 8)) {
            for ($j = $ibStart + $i; $j -lt ($cbSize + $ibStart); $j += $WidthInBits) {
                $data[$vectorArrayIndex] = $data[$vectorArrayIndex] -bxor ([UInt64]$buffer[$j] -shl $vectorOffset)
            }
        } else {
            $index1 = $vectorArrayIndex

            # $index2 = $isLastCell ? 0 : ($vectorArrayIndex + 1)
            $index2 = if( $isLastCell )
            {
                0
            }
            else
            {
                $vectorArrayIndex + 1
            }

            $low = $bitsInVectorCell - $vectorOffset

            $xoredByte = 0
            for ($j = $ibStart + $i; $j -lt ($cbSize + $ibStart); $j += $WidthInBits) {
                $xoredByte = $xoredByte -bxor $buffer[$j]
            }

            $data[$index1] = $data[$index1] -bxor ([UInt64]$xoredByte -shl $vectorOffset)
            $data[$index2] = $data[$index2] -bxor ([UInt64]$xoredByte -shr $low)
        }

        $vectorOffset += $Shift
        while ($vectorOffset -ge $bitsInVectorCell) {

            # $vectorArrayIndex = $isLastCell ? 0 : ($vectorArrayIndex + 1)
            $vectorArrayIndex = if( $isLastCell )
            {
                0
            }
            else
            {
                $vectorArrayIndex + 1
            }


            $vectorOffset -= $bitsInVectorCell
        }
    }

    $shiftSoFar = ($shiftSoFar + $Shift * ($cbSize % $WidthInBits)) % $WidthInBits

    # Finalize hash
    $rgb = New-Object byte[] 20
    for ($i = 0; $i -lt $data.Length - 1; $i++) {
        [System.Buffer]::BlockCopy([BitConverter]::GetBytes($data[$i]), 0, $rgb, $i * 8, 8)
    }

    $lastIndex = ($data.Length - 1)
    [System.Buffer]::BlockCopy([BitConverter]::GetBytes($data[$lastIndex]), 0, $rgb, $lastIndex * 8, $rgb.Length - ($lastIndex * 8))

    $lengthBytes = [BitConverter]::GetBytes([Int64]$lengthSoFar)
    for ($i = 0; $i -lt $lengthBytes.Length; $i++) {
        $rgb[($WidthInBits / 8) - $lengthBytes.Length + $i] = $rgb[($WidthInBits / 8) - $lengthBytes.Length + $i] -bxor $lengthBytes[$i]
    }

    return [Convert]::ToBase64String($rgb)
}


$qXorHash = Get-QuickXorHash -FilePath "C:\_temp\copilot_users.csv"

$qXorHash -eq "pZHOeTBqkVraoHRepaXj7huIYVM="