====== 5.1 P/Invoke - DLLs einbinden ======

Diese Seite zeigt, wie Sie OpenSSL über P/Invoke in .NET nutzen.

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===== Was ist P/Invoke? =====

**P/Invoke** (Platform Invoke) ermöglicht den Aufruf von nativen DLL-Funktionen aus .NET:

<code>
.NET Code  →  P/Invoke  →  libcrypto-3-x64.dll  →  OpenSSL
</code>

----

===== DLLs vorbereiten =====

==== 1. DLLs in Projekt kopieren ====

<code powershell>
cd MeinProjekt
copy "D:\Projects\openssl-3.6.0\bin\bin\libcrypto-3-x64.dll" .\
copy "D:\Projects\openssl-3.6.0\bin\bin\libssl-3-x64.dll" .\
</code>

==== 2. .csproj anpassen ====

<code xml>
<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <!-- OpenSSL Native Libraries -->
    <None Update="libcrypto-3-x64.dll">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
    <None Update="libssl-3-x64.dll">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
  </ItemGroup>
</Project>
</code>

----

===== Einfaches P/Invoke Beispiel =====

<code csharp>
using System;
using System.Runtime.InteropServices;

namespace MeinProjekt;

/// <summary>
/// OpenSSL P/Invoke Bindings
/// </summary>
public static class OpenSslInterop
{
    private const string LIBCRYPTO = "libcrypto-3-x64.dll";

    // Initialisierung
    [DllImport(LIBCRYPTO, CallingConvention = CallingConvention.Cdecl)]
    public static extern int OPENSSL_init_crypto(ulong opts, IntPtr settings);

    // Version abrufen
    [DllImport(LIBCRYPTO, CallingConvention = CallingConvention.Cdecl)]
    public static extern IntPtr OpenSSL_version(int type);

    // Konstanten
    public const int OPENSSL_VERSION_STRING = 6;
    public const ulong OPENSSL_INIT_LOAD_CRYPTO_STRINGS = 0x00000002;
    public const ulong OPENSSL_INIT_ADD_ALL_CIPHERS = 0x00000004;
    public const ulong OPENSSL_INIT_ADD_ALL_DIGESTS = 0x00000008;

    /// <summary>
    /// Initialisiert OpenSSL
    /// </summary>
    public static void Initialize()
    {
        OPENSSL_init_crypto(
            OPENSSL_INIT_LOAD_CRYPTO_STRINGS |
            OPENSSL_INIT_ADD_ALL_CIPHERS |
            OPENSSL_INIT_ADD_ALL_DIGESTS,
            IntPtr.Zero);
    }

    /// <summary>
    /// Gibt die OpenSSL-Version zurück
    /// </summary>
    public static string GetVersion()
    {
        var ptr = OpenSSL_version(OPENSSL_VERSION_STRING);
        return Marshal.PtrToStringAnsi(ptr) ?? "Unknown";
    }
}

// Verwendung:
class Program
{
    static void Main()
    {
        OpenSslInterop.Initialize();
        Console.WriteLine($"OpenSSL Version: {OpenSslInterop.GetVersion()}");
    }
}
</code>

----

===== ML-DSA Schlüsselgenerierung =====

<code csharp>
public static class MlDsaInterop
{
    private const string LIBCRYPTO = "libcrypto-3-x64.dll";

    [DllImport(LIBCRYPTO)] private static extern IntPtr EVP_PKEY_CTX_new_from_name(IntPtr libctx, string name, IntPtr propq);
    [DllImport(LIBCRYPTO)] private static extern int EVP_PKEY_keygen_init(IntPtr ctx);
    [DllImport(LIBCRYPTO)] private static extern int EVP_PKEY_keygen(IntPtr ctx, out IntPtr pkey);
    [DllImport(LIBCRYPTO)] private static extern void EVP_PKEY_CTX_free(IntPtr ctx);
    [DllImport(LIBCRYPTO)] private static extern void EVP_PKEY_free(IntPtr pkey);
    [DllImport(LIBCRYPTO)] private static extern int i2d_PrivateKey(IntPtr pkey, ref IntPtr pp);
    [DllImport(LIBCRYPTO)] private static extern int i2d_PUBKEY(IntPtr pkey, ref IntPtr pp);
    [DllImport(LIBCRYPTO)] private static extern void OPENSSL_free(IntPtr ptr);

    /// <summary>
    /// Generiert ein ML-DSA-65 Schlüsselpaar
    /// </summary>
    public static (byte[] privateKey, byte[] publicKey) GenerateMlDsa65KeyPair()
    {
        IntPtr ctx = EVP_PKEY_CTX_new_from_name(IntPtr.Zero, "mldsa65", IntPtr.Zero);
        if (ctx == IntPtr.Zero)
            throw new Exception("Failed to create context");

        try
        {
            if (EVP_PKEY_keygen_init(ctx) <= 0)
                throw new Exception("Failed to init keygen");

            IntPtr pkey;
            if (EVP_PKEY_keygen(ctx, out pkey) <= 0)
                throw new Exception("Failed to generate key");

            try
            {
                // Private Key exportieren
                IntPtr privPtr = IntPtr.Zero;
                int privLen = i2d_PrivateKey(pkey, ref privPtr);
                byte[] privateKey = new byte[privLen];
                Marshal.Copy(privPtr, privateKey, 0, privLen);
                OPENSSL_free(privPtr);

                // Public Key exportieren
                IntPtr pubPtr = IntPtr.Zero;
                int pubLen = i2d_PUBKEY(pkey, ref pubPtr);
                byte[] publicKey = new byte[pubLen];
                Marshal.Copy(pubPtr, publicKey, 0, pubLen);
                OPENSSL_free(pubPtr);

                return (privateKey, publicKey);
            }
            finally
            {
                EVP_PKEY_free(pkey);
            }
        }
        finally
        {
            EVP_PKEY_CTX_free(ctx);
        }
    }
}
</code>

----

===== Vollständige Interop-Klasse =====

Für eine vollständige P/Invoke-Implementierung siehe:

→ [[de:int:pqcrypt:api:start|WvdS.System.Security.Cryptography API]]

Diese Bibliothek enthält:
  * ML-DSA Signieren/Verifizieren
  * ML-KEM Encapsulation/Decapsulation
  * X.509-Zertifikate mit PQ-Algorithmen
  * Hybride Signaturen

----

===== Häufige Fehler =====

==== "DLL not found" ====

<code>
System.DllNotFoundException: Unable to load DLL 'libcrypto-3-x64.dll'
</code>

**Lösung:**
  - DLLs im Ausgabeverzeichnis (bin/Debug/) vorhanden?
  - .csproj ''CopyToOutputDirectory'' korrekt?
  - Plattform stimmt? (x64 vs x86)

==== "Entry point not found" ====

<code>
System.EntryPointNotFoundException: Unable to find entry point 'XYZ'
</code>

**Lösung:**
  - Funktionsname korrekt geschrieben?
  - ''CallingConvention.Cdecl'' gesetzt?
  - OpenSSL-Version unterstützt die Funktion?

==== Speicherlecks ====

<WRAP important>
**Immer Ressourcen freigeben!**

  * ''EVP_PKEY_free(pkey)''
  * ''EVP_PKEY_CTX_free(ctx)''
  * ''OPENSSL_free(ptr)''
</WRAP>

----

===== Tipps =====

<WRAP tip>
**LibraryImport statt DllImport (ab .NET 7)**

<code csharp>
// Moderner Ansatz
[LibraryImport("libcrypto-3-x64.dll")]
public static partial int OPENSSL_init_crypto(ulong opts, IntPtr settings);
</code>
</WRAP>

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===== Weiter zu =====

  * [[.:nuget-grundlagen|NuGet-Paket erstellen]]
  * [[.:blazor-wasm|Blazor WASM Integration]]
  * [[.:verteilung:start|6. Verteilung]]

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