~~NOTOC~~
====== Scenario 8.2: Sign Code ======

<WRAP round info>
**Category:** [[.:start|Digital Signatures]] \\
**Complexity:** ⭐⭐⭐⭐ (High) \\
**Prerequisites:** Code signing certificate \\
**Estimated Time:** 20-30 Minutes
</WRAP>

----

===== Description =====

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

----

===== Workflow =====

<mermaid>
flowchart LR
    CODE[Executable/DLL] --> HASH[Authenticode Hash]
    HASH --> SIGN[ML-DSA + RSA Signature]
    KEY[Code Signing Key] --> SIGN
    SIGN --> TS[Add Timestamp]
    TSA[TSA Server] --> TS
    TS --> OUTPUT[Signed File]

    style SIGN fill:#e8f5e9
    style TS fill:#fff3e0
</mermaid>

----

===== Code Example: Authenticode Signing =====

<code csharp>
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}");
</code>

----

===== Windows SignTool Integration =====

<code csharp>
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;
    }
}
</code>

----

===== Sign PowerShell Script =====

<code csharp>
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";
    }
}
</code>

----

===== Sign NuGet Package =====

<code csharp>
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}");
    }
}
</code>

----

===== Dual Signature (Legacy + PQ) =====

For transition period: Both signatures in parallel

<code csharp>
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)");
    }
}
</code>

----

===== Timestamp Servers =====

^  Provider  ^  URL  ^  Protocol  ^
| DigiCert | http://timestamp.digicert.com | RFC 3161 |
| Sectigo | http://timestamp.sectigo.com | RFC 3161 |
| GlobalSign | http://timestamp.globalsign.com | RFC 3161 |
| SSL.com | http://ts.ssl.com | RFC 3161 |

<WRAP round alert>
**IMPORTANT:** Without a timestamp, the signature becomes invalid after the certificate expires!
</WRAP>

----

===== Industry-Specific Requirements =====

^  Industry  ^  Standard  ^  Requirements  ^
| **Windows** | Authenticode | EV certificate for SmartScreen |
| **Automotive** | UNECE R156 | Firmware signing, HSM |
| **Healthcare** | DiGAV | Qualified signature |
| **Industry** | IEC 62443 | PLC firmware |

----

===== Related Scenarios =====

^  Relationship  ^  Scenario  ^  Description  ^
| **Prerequisite** | [[en:int:pqcrypt:szenarien:zertifikate:codesign_cert|3.3 Code Signing Certificate]] | Create certificate |
| **Important** | [[.:timestamp|8.3 Timestamp]] | Long-term validity |
| **Related** | [[.:signatur_verifizieren|8.4 Verify Signature]] | Validation |

----

<< [[.:dokument_signieren|← 8.1 Sign Document]] | [[.:start|↑ Signatures Overview]] | [[.:timestamp|8.3 Timestamp →]] >>

{{tag>scenario signature code authenticode powershell nuget}}

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