PowerShell script to cryptographically sign assemblies that's easy to use with a Continuous Integration server

Sign.ps1

$script:SignToolPath = "C:\Program Files (x86)\Windows Kits\8.1\bin\x64\signtool.exe"
$script:TimestampServers = "http://timestamp.comodoca.com/authenticode",
    "http://timestamp.verisign.com/scripts/timestamp.dll",
    "http://timestamp.digicert.com"
$script:TimestampServerIndex = 0
$script:MaxRetries = 7

$ErrorActionPreference = "Stop"
Set-StrictMode -Version 3.0

if (!$Args) {
    throw "Please specify assemblies to sign by appending parameters."
}

function sign([string]$file) {
    
    $server = $TimestampServers[$TimestampServerIndex]
    $signToolArgs = @("sign", "/t", $server, "/v", $file)
    
    & $SignToolPath $signToolArgs
    $signResult = $LASTEXITCODE

    if ($signResult -eq 1) {
        
        # We had an error, probably with the timestamp server. Change which
        # server we'll use for the next signing operation and notify the caller
        # of the error.
        
        $script:TimestampServerIndex++
        if ($script:TimestampServerIndex -ge $TimestampServers.Count) {
            $script:TimestampServerIndex = 0
        }
        
        throw "signtool exited with code $signResult"
    }
    elseif ($signResult -eq 2) {
        Write-Warning "signtool exited with code $signResult"
    }
}

for ($i = 0; $i -lt $Args.Count; $i++) {
    
    for ($retryCount = 0; $retryCount -lt $MaxRetries; $retryCount++) {
        
        try {
            
            $output = sign $Args[$i]
            
            # Sign was successful. Exit from the retry loop.
            $output | Write-Host
            break
        }
        catch {
            if ($retryCount -eq $MaxRetries - 1) {
                throw $_
            }
        }
        
        # A failure happened. Will now allow the retry loop to continue.
        Write-Host "Encountered a failure. Retrying... ($($retryCount + 1) of $MaxRetries)"
        Start-Sleep -Seconds 5
    }
    
    if ($i -ne $Args.Count - 1) {
        
        # We need to be kind to the timestamp server. Let's pause so we don't
        # hammer it constantly.
        Start-Sleep -Seconds 15
    }
}