$Path = "D:\FTP\MailServerLogs"
$TargetFolder = Get-ChildItem "$Path" -Recurse
$CryptoServiceProvider = [System.Security.Cryptography.MD5CryptoServiceProvider];
$HashAlgorithm = New-Object $CryptoServiceProvider
foreach ($File in $TargetFolder)
{
    $FileName = $File.Name
    $FilePath = $File.DirectoryName
    $SigName = $FileName + ".sign"
    $SigPath = $FilePath + "\" + $SigName
	$DateName = $FileName + ".date"
	$DatePath = $FilePath + "\" + $DateName
 
	if ((Test-Path $DatePath) -eq "True")
    {
        Write-Host "Date file is already exist."
    }
    else
	{
		$DateString = Get-Date -uformat "%d.%m.%Y"
		$TimeString = (w32tm /stripchart /computer:time.ume.tubitak.gov.tr /samples:1)[-1].split("")[0]
		$DateString = $DateString + " " + $TimeString
		$DateFile = New-Item -Path "$FilePath" -Name $DateName -type "file" -value $DateString
	}
 
	if ((Test-Path $SigPath) -eq "True")
    {
        Write-Host "Hashtag is already exist."
    }
    else
    {
        $Fc = Get-Content $FilePath\$FileName
        if ($Fc.Count -gt 0) 
        { 
            $Encoding = New-Object System.Text.ASCIIEncoding 
            $Bytes = $Encoding.GetBytes($Fc)
            $HashByteArray = $HashAlgorithm.ComputeHash($Bytes)
            $Hashstring = ""
            foreach ($Byte in $HashByteArray) {$Hashstring += $Byte.tostring("x2")}
            $SigFile = New-Item -Path "$FilePath" -Name $SigName -type "file" -value $Hashstring
            Start-Sleep -m 500
        }
    }
 
	$HashTag = Get-Content $FilePath\$SigName
	$HashTag = $HashTag + $DateString
	Remove-Item -Path $FilePath\$SigName
	$Encoding = New-Object System.Text.ASCIIEncoding 
    $Bytes = $Encoding.GetBytes($HashTag)
    $HashByteArray = $HashAlgorithm.ComputeHash($Bytes)
    $Hashstring = ""
    foreach ($Byte in $HashByteArray) {$Hashstring += $Byte.tostring("x2")}
    $SigFile = New-Item -Path "$FilePath" -Name $SigName -type "file" -value $Hashstring
 
	Write-Host "$FileName is signed!"
}