Questo scenario descrive l'emissione di un certificato client per autenticazione mTLS. I certificati client consentono l'autenticazione forte di utenti o servizi verso i server.

Casi d'uso:

• Accesso API mTLS
• Autenticazione service-to-service
• Accesso VPN
• Login Smart Card / PIV

using WvdS.Security.Cryptography.X509Certificates.Extensions.PQ;
 
using var ctx = PqCryptoContext.Initialize();
 
// Intermediate-CA laden
var caCert = ctx.LoadCertificate("intermediate-ca.crt.pem");
var caKey = ctx.LoadPrivateKey("intermediate-ca.key.pem", "CaPassword!");
 
// CSR laden
var csr = ctx.LoadCertificateRequest(File.ReadAllText("client.csr.pem"));
csr.VerifySignature();
 
// Client-Zertifikat ausstellen
var clientCert = ctx.IssueCertificate(
    csr,
    issuerCert: caCert,
    issuerKey: caKey,
    serialNumber: ctx.GenerateSerialNumber(),
    validDays: 365,
    extensions: new ExtBuilder()
        .BasicConstraints(ca: false, critical: true)
        // Key Usage: Nur Signatur (kein Key Encipherment für Clients)
        .KeyUsage(KeyUsageFlags.DigitalSignature, critical: true)
        // Extended Key Usage: Client Auth
        .ExtendedKeyUsage(ExtKeyUsage.ClientAuth)
        .SubjectKeyIdentifier(csr.PublicKey)
        .AuthorityKeyIdentifier(caCert)
        .CrlDistributionPoint("http://crl.example.com/intermediate.crl")
        .Build()
);
 
clientCert.ToPemFile("client.crt.pem");
Console.WriteLine($"Client-Zertifikat ausgestellt: {clientCert.Subject}");

Per microservizi e sistemi automatizzati:

// Service-Zertifikat mit Service-Account-Namen
var serviceCert = ctx.IssueCertificate(
    csr,
    issuerCert: caCert,
    issuerKey: caKey,
    validDays: 90,  // Kurze Gültigkeit für automatische Rotation
    extensions: new ExtBuilder()
        .BasicConstraints(ca: false)
        .KeyUsage(KeyUsageFlags.DigitalSignature)
        .ExtendedKeyUsage(ExtKeyUsage.ClientAuth)
        // Service-spezifische SANs
        .SubjectAlternativeName(new[] {
            "dns:payment-service.internal",
            "uri:spiffe://cluster.local/ns/default/sa/payment-service"
        })
        .Build()
);

// PFX erstellen für Import in Browser/Windows
var pfxData = ctx.ExportToPfx(
    certificate: clientCert,
    privateKey: clientKey,
    chain: new[] { caCert },
    password: "UserPassword123!",
    friendlyName: "Max Mustermann - Client Cert"
);
 
File.WriteAllBytes("client.pfx", pfxData);

« ← 3.1 Certificato server | ↑ Panoramica certificati | 3.3 Code-Signing → »

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