Add-SignatureToScript.ps1

<#
.SYNOPSIS
    Signs a PS1 script with the local users code signing certificate.
.DESCRIPTION
    Takes a PS1 file as an argument and signs with the local user's code signing certificate.
    Optionally allows specification of a timestamp server.
.PARAMETER Path
    A PS1 file to sign. Accepts pipeline input.
.PARAMETER TimestampServer
    An optional parameter specifying a timestamp server. The default is 'http://timestamp.comodoca.com/authenticode'.
.OUTPUTS
    A boolean, indicating whether the script was signed.
#>
Function Add-SignatureToScript {

    [CmdletBinding()]
        param(
        [parameter(Mandatory=$true, Position=1, ValueFromPipeline=$True)]
        [ValidateScript({
        
            if ( [IO.Path]::GetExtension( $_ ) -notmatch '.psm?1' ) {

                throw "Path must point to an PS1 file."

            }
            
            $true
            
        })]
        [ValidateScript({
        
            if ( -not ( Test-Path $_ -PathType Leaf -ErrorAction SilentlyContinue ) ) {

                throw "[$_] is not a file."

            }

            $true
            
        })]
        [ValidateScript({
        
            if ( -not ( Test-Path $_ -ErrorAction SilentlyContinue ) ) {

                throw "[$_] does not exist."

            }

            $true
            
        })]
        [System.IO.FileInfo[]]
        $Path,

        [parameter( Mandatory=$false )]
        [ValidateNotNullOrEmpty()]
        [string]
        $TimestampServer="http://timestamp.comodoca.com/authenticode"

    )

    process {

        foreach ( $PathItem in $Path ) {

            $Options = @{

                FilePath = $PathItem
                Certificate = ( Get-ChildItem -Path Cert:\CurrentUser\My -CodeSigningCert )
                TimestampServer = $TimestampServer

            }

            Set-AuthenticodeSignature @Options

        }

    }

}