function Compress-Certificates {
<#
.SYNOPSIS
    Combine Certificates into a .zip File.
#>
    [CmdletBinding()]
    param(
        $Certificates,
        $TempFolder
    )
    #Prepare certificate folders by zipping them.
    foreach ($certificate in $Certificates) {
        $zipFileName = $certificate.Name.Trim() + ".zip"
        $CompressedDir = $TempFolder, $zipFileName -join "\"
        Remove-Item $CompressedDir -Force -ErrorAction SilentlyContinue
        Remove-Item (Join-Path $certificate.Folder $zipFileName) -Force -ErrorAction SilentlyContinue
        [System.IO.Compression.ZipFile]::CreateFromDirectory($certificate.Folder,
            $CompressedDir, [System.IO.Compression.CompressionLevel]::Optimal, $false)
        Move-Item $CompressedDir $certificate.Folder -Force
    }
}