sign.ps1

<#
.Synopsis
   Signs a script 
.DESCRIPTION
   Gets a users code signing certificate, (if there is just one in "Cert:\CurrentUser\My" it will be selected automatically)  
   and uses it to sign a script file using a timestamping service.
   Without the Time Stamp (Comodo CA is used by default) the signature is only valid for the range of dates on the certificate  
   If -passthrough is specified, retuns the certificate object 
   Else, if -quiet is specified doesn't reurn anything
   Otherwise outputs the detail of the signature
   
.EXAMPLE
    Sign .\sign.ps1
    Signs this file
.EXAMPLE
   sign .\sign.ps1 -certPath Cert:\CurrentUser\My\2BC8A723CD7DCFC06DF50C8311512E798B954D89
   Signs the file, but this time with a specific certificate (e.g. if you have more than one)
.EXAMPLE
   Get-AuthenticodeSignature .\sig*.ps1 | where Status -ne "Valid" | sign
   Gets files which don't have a valid signature, and signs them 
.INPUTS
   Files can be piped into sign
#>

param (  #The File to be signed (wild cards work)
         [parameter(Mandatory=$true,ValueFromPipelineByPropertyName=$true)]
         [Alias("PSPath")]$path, 
         #the path to a container which holds a code signing certificate, or to a sing certificate
         $certPath   ="Cert:\CurrentUser\My" , 
         #The URL for a public cryptographic time stamp service
         $TimeServer = "http://timestamp.comodoca.com/authenticode",
         #Do not return any output 
         [switch]$quiet, 
         #Return output as a signature object  
         [switch]$passthru) 
begin   {#Get the Certificate  
          $cert=Get-ChildItem -CodeSigningCert -Path $certPath }
Process {#If we got it OK, sign and return the signature as dictated by -quiet / -passthrough ; otherwise give a warning. 
          if (-not $cert) {Write-Warning -Message "Couldn't find a signing certificate for you to sign $path; you can try using -certpath"}
          else            {$Sig = Set-AuthenticodeSignature -Certificate $cert -FilePath $path -TimestampServer $TimeServer 
                           if    (-not $sig.TimeStamperCertificate) {Write-Warning -Message "$path Does not appear to be properly signed."} 
                           elseif(     $passthru)                   {$sig }
                           elseif(-not $quiet)                      {$sig | Format-List} 
          }   
}