Use dynamic password on file Compression - powershell

Question

I created a powershell script to archive files older than X months in a directory. I would like to make the password for each compressed file different but this seems to be quite a challenge as winrar passes my variable thru as the password instead of the variable value. I have tried placing the variable into brackets which then just causes it to ask me for the password. Have also tried placing it into quotes but still it does not work and uses the variable name as the password. I tried it on the latest version of powershell using quotes which seems to work but the problem is the machine I want to run this on cannot be upgraded at current due to server availability requirements thus a restart of the server is not an option
$SourcePath = "C:\FTP\Hollard\PrankCall"
$MonthsBack = 6
$masterPassword = "Password"
$RarApp = "C:\Program Files\WinRAR\Rar.exe"
$Source = Get-ChildItem $SourcePath -Recurse | where {($_.LastWriteTime -LT $(Get-Date).AddMonths(-$MonthsBack)) -and ($_.Directory.Name -notmatch "Archive")}
ForEach ($files in $Source) {
$Destination = [System.String]::Concat($files.Directory, "\Archive\")
$FileYear = $files.LastWriteTime.year
$FileMonth = [System.String]::Concat("0",$files.LastWriteTime.Month)
$FileMonth = $FileMonth.Substring($FileMonth.Length - 2,2)
$ZipFileName = [System.String]::Concat($files.Directory.Name,"_",$FileYear , $FileMonth,".rar")
$zipFilePassword = [System.String]::Concat($masterPassword , $FileYear , $FileMonth)
if(!(Test-Path -Path $Destination )){
New-Item -ItemType directory -Path $Destination
}
& $RarApp a $($Destination + $ZipFileName) $($files.FullName) -m0 -hp$zipFilePassword -df -ep
}

Answer 1

Try this:
& $RarApp a $($Destination + $ZipFileName) $($files.FullName) -m0 "-hp$zipFilePassword" -df -ep
The problem is that the PowerShell parser thinks the parameters you're trying to pass to rar.exe might be parameters for a ScriptBlock or PowerShell command, so it thinks there's a switch parameter literally named -hp$zipFilePassword so it doesn't expand it.