Namespace: WvdS.System.Security.Cryptography.X509Certificates

Drop-in replacement extensions for X509Chain with post-quantum signature validation. Extends the standard chain validation with PQ signature checking in all three crypto modes.

using var chain = new X509Chain();
var cert = new X509Certificate2("certificate.pfx");
 
// With explicit CryptoMode
bool isValid = chain.Build(cert, CryptoMode.Hybrid);
 
// With default mode from CryptoConfig
bool isValid2 = chain.Build(cert, null);

// With X509Certificate2Collection
var trustAnchors = new X509Certificate2Collection();
trustAnchors.Add(rootCa);
 
using var chain = new X509Chain();
bool isValid = chain.Build(cert, trustAnchors, CryptoMode.Hybrid);
 
// With PqTrustStore
var trustStore = PqTrustStore.LoadFromPem("truststore.pem");
bool isValid2 = chain.Build(cert, trustStore, CryptoMode.Hybrid);

using var chain = new X509Chain();
bool isValid = chain.BuildWithRevocationCheck(
    certificate,
    customTrustStore,
    X509RevocationMode.Online,  // or Offline
    CryptoMode.Hybrid);

For air-gapped environments or when CRL download is not possible:

// Load CRLs
var crlData = new List<byte[]>
{
    File.ReadAllBytes("root-ca.crl"),
    File.ReadAllBytes("intermediate-ca.crl")
};
 
using var chain = new X509Chain();
bool isValid = chain.BuildWithOfflineCrl(
    certificate,
    customTrustStore,
    crlData,
    CryptoMode.Hybrid);

using var chain = new X509Chain();
chain.Build(cert, CryptoMode.Hybrid);
 
if (chain.IsFullyPqProtected())
{
    Console.WriteLine("Entire chain is PQ protected");
}
else
{
    // Which certificates are not PQ protected?
    var modes = chain.GetChainCryptoModes();
    for (int i = 0; i < modes.Length; i++)
    {
        if (modes[i] == CryptoMode.Classic)
        {
            Console.WriteLine($"Element {i} has no PQ protection");
        }
    }
}

Creates a detailed report about chain validation:

using var chain = new X509Chain();
chain.Build(cert, CryptoMode.Hybrid);
 
var report = chain.GetValidationReport();
Console.WriteLine(report.ToString());
 
// Individual properties:
Console.WriteLine($"Valid: {report.IsValid}");
Console.WriteLine($"Chain length: {report.ChainLength}");
Console.WriteLine($"Fully PQ protected: {report.IsFullyPqProtected}");
 
// Details per element:
foreach (var element in report.Elements)
{
    Console.WriteLine($"  {element.Subject}");
    Console.WriteLine($"    Mode: {element.CryptoMode}");
    Console.WriteLine($"    Has PQ keys: {element.HasPqKeys}");
}

• X509Certificate2Extensions
• TrustStoreExtensions
• RevocationExtensions
• Crypto Modes Explained

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