This scenario describes signing code and executables with Post-Quantum secure algorithms. Code signing enables:

• Authentication of the software publisher
• Integrity protection against tampering
• Trustworthiness for end users
• Compliance with security policies

Supported Formats:

• Windows Authenticode (EXE, DLL, MSI)
• PowerShell Scripts (.ps1)
• NuGet Packages (.nupkg)
• Java JAR Files
• macOS Code Signature

using WvdS.Security.Cryptography.X509Certificates.Extensions.PQ;
using System.Security.Cryptography;
 
using var ctx = PqCryptoContext.Initialize();
 
// Load code signing certificate and key
var codeSignCert = ctx.LoadCertificate("codesign.crt.pem");
var codeSignKey = ctx.LoadPrivateKey("codesign.key.pem", "KeyPassword!");
 
// Create Authenticode signature
var signatureOptions = new AuthenticodeSignatureOptions
{
    Certificate = codeSignCert,
    PrivateKey = codeSignKey,
    HashAlgorithm = HashAlgorithmName.SHA256,
    TimestampUrl = "http://timestamp.digicert.com",
    TimestampHashAlgorithm = HashAlgorithmName.SHA256,
    Mode = CryptoMode.Hybrid,
    Description = "MyApp - Secure Application",
    DescriptionUrl = "https://myapp.example.com"
};
 
// Sign EXE
var inputPath = "MyApp.exe";
var outputPath = "MyApp-signed.exe";
 
ctx.SignAuthenticode(inputPath, outputPath, signatureOptions);
 
Console.WriteLine($"Code signed: {outputPath}");
Console.WriteLine($"  Signer: {codeSignCert.Subject}");
Console.WriteLine($"  Timestamp: {signatureOptions.TimestampUrl}");

public class SignToolWrapper
{
    public void Sign(string filePath, string pfxPath, string password, string timestampUrl)
    {
        var process = new Process
        {
            StartInfo = new ProcessStartInfo
            {
                FileName = "signtool.exe",
                Arguments = $"sign " +
                    $"/fd SHA256 " +
                    $"/f \"{pfxPath}\" " +
                    $"/p \"{password}\" " +
                    $"/tr \"{timestampUrl}\" " +
                    $"/td SHA256 " +
                    $"/d \"Signed with PQ-Crypto\" " +
                    $"\"{filePath}\"",
                RedirectStandardOutput = true,
                RedirectStandardError = true,
                UseShellExecute = false
            }
        };
 
        process.Start();
        process.WaitForExit();
 
        if (process.ExitCode != 0)
        {
            var error = process.StandardError.ReadToEnd();
            throw new InvalidOperationException($"SignTool failed: {error}");
        }
 
        Console.WriteLine($"Signed: {filePath}");
    }
 
    public bool Verify(string filePath)
    {
        var process = new Process
        {
            StartInfo = new ProcessStartInfo
            {
                FileName = "signtool.exe",
                Arguments = $"verify /pa /v \"{filePath}\"",
                RedirectStandardOutput = true,
                UseShellExecute = false
            }
        };
 
        process.Start();
        process.WaitForExit();
 
        return process.ExitCode == 0;
    }
}

public class PowerShellSigner
{
    public void SignScript(string scriptPath, X509Certificate2 cert)
    {
        // Add PowerShell CMS signature
        var scriptContent = File.ReadAllText(scriptPath);
 
        // Create signature block
        var signatureBlock = CreatePowerShellSignature(scriptContent, cert);
 
        // Append signature to script
        var signedContent = scriptContent + Environment.NewLine + signatureBlock;
        File.WriteAllText(scriptPath, signedContent);
 
        Console.WriteLine($"PowerShell script signed: {scriptPath}");
    }
 
    private string CreatePowerShellSignature(string content, X509Certificate2 cert)
    {
        using var ctx = PqCryptoContext.Initialize();
 
        // Hash the script
        var hash = SHA256.HashData(Encoding.UTF8.GetBytes(content));
 
        // CMS signature
        var contentInfo = new ContentInfo(hash);
        var signedCms = new SignedCms(contentInfo, true);
        var signer = new CmsSigner(cert);
        signedCms.ComputeSignature(signer);
 
        // Base64 encoded signature block
        var signatureBase64 = Convert.ToBase64String(signedCms.Encode());
 
        return $@"
# SIG # Begin signature block
# {signatureBase64}
# SIG # End signature block";
    }
}

public class NuGetSigner
{
    public async Task SignPackage(
        string packagePath,
        X509Certificate2 cert,
        AsymmetricAlgorithm privateKey,
        string timestampUrl)
    {
        using var ctx = PqCryptoContext.Initialize();
 
        // Open NuGet package
        using var package = new ZipArchive(File.Open(packagePath, FileMode.Open), ZipArchiveMode.Update);
 
        // Create .signature.p7s
        var signatureEntry = package.CreateEntry(".signature.p7s");
 
        // Calculate package hash (without signature entry)
        var packageHash = ComputePackageHash(package);
 
        // CMS signature
        var contentInfo = new ContentInfo(packageHash);
        var signedCms = new SignedCms(contentInfo, true);
        var signer = new CmsSigner(cert)
        {
            DigestAlgorithm = new Oid("2.16.840.1.101.3.4.2.1"),
            IncludeOption = X509IncludeOption.WholeChain
        };
 
        signedCms.ComputeSignature(signer, mode: CryptoMode.Hybrid);
 
        // Add timestamp
        await AddTimestamp(signedCms, timestampUrl);
 
        // Write signature
        using var signatureStream = signatureEntry.Open();
        signatureStream.Write(signedCms.Encode());
 
        Console.WriteLine($"NuGet package signed: {packagePath}");
    }
}

For transition period: Both signatures in parallel

public class DualSignature
{
    public void SignWithDualSignature(string exePath, SigningCredentials credentials)
    {
        using var ctx = PqCryptoContext.Initialize();
 
        // 1. First signature: SHA-1 (for Windows XP/Vista compatibility)
        ctx.SignAuthenticode(exePath, exePath, new AuthenticodeSignatureOptions
        {
            Certificate = credentials.LegacyCert,
            PrivateKey = credentials.LegacyKey,
            HashAlgorithm = HashAlgorithmName.SHA1,
            TimestampUrl = credentials.TimestampUrl,
            AppendSignature = false  // First signature
        });
 
        // 2. Second signature: SHA-256 + PQ (for modern systems)
        ctx.SignAuthenticode(exePath, exePath, new AuthenticodeSignatureOptions
        {
            Certificate = credentials.PqCert,
            PrivateKey = credentials.PqKey,
            HashAlgorithm = HashAlgorithmName.SHA256,
            Mode = CryptoMode.Hybrid,
            TimestampUrl = credentials.TimestampUrl,
            AppendSignature = true  // Append second signature
        });
 
        Console.WriteLine("Dual signature created (SHA-1 + SHA-256/PQ)");
    }
}

« ← 8.1 Sign Document | ↑ Signatures Overview | 8.3 Timestamp → »

Wolfgang van der Stille @ EMSR DATA d.o.o. - Post-Quantum Cryptography Professional