~~NOTOC~~
====== Scenario 6.1: Creare CRL ======

<WRAP round info>
**Categoria:** [[.:start|Revoca (Revocation)]] \\
**Complessità:** Media \\
**Prerequisiti:** Certificato e chiave CA \\
**Tempo stimato:** 15-20 minuti
</WRAP>

----

===== Descrizione =====

Questo scenario descrive la **creazione di una Certificate Revocation List (CRL)** secondo RFC 5280. Le CRL sono liste firmate di certificati revocati, pubblicate dalle CA.

**Campi CRL:**
  * **issuer** - DN della CA emittente
  * **thisUpdate** - Timestamp di emissione
  * **nextUpdate** - Prossimo aggiornamento pianificato
  * **revokedCertificates** - Lista dei numeri seriali revocati
  * **signature** - Firma della CA

----

===== Workflow =====

<mermaid>
flowchart LR
    REV[Certificati revocati] --> BUILD[CRL Builder]
    BUILD --> SIGN[Firmare con CA]
    SIGN --> PUBLISH[Pubblicare]
    PUBLISH --> CDP[Aggiornare CDP URL]

    style SIGN fill:#e8f5e9
</mermaid>

----

===== Esempio codice (C#) =====

<code csharp>
using WvdS.Security.Cryptography.X509Certificates.Extensions.PQ;
using System.Security.Cryptography.X509Certificates;

using var ctx = PqCryptoContext.Initialize();

// CA laden
var caCert = ctx.LoadCertificate("intermediate-ca.crt.pem");
var caKey = ctx.LoadPrivateKey("intermediate-ca.key.pem", "CaPassword!");

// CRL Builder erstellen
var crlBuilder = new CertificateRevocationListBuilder();

// Widerrufene Zertifikate hinzufügen
crlBuilder.AddEntry(
    serialNumber: new byte[] { 0x01, 0x02, 0x03 },
    revocationTime: new DateTimeOffset(2024, 6, 15, 10, 30, 0, TimeSpan.Zero),
    reason: X509RevocationReason.KeyCompromise
);

crlBuilder.AddEntry(
    serialNumber: new byte[] { 0x01, 0x02, 0x04 },
    revocationTime: DateTimeOffset.UtcNow.AddDays(-7),
    reason: X509RevocationReason.CessationOfOperation
);

// CRL generieren
byte[] crlBytes = crlBuilder.Build(
    issuerCertificate: caCert,
    crlNumber: BigInteger.Parse("1000"),
    nextUpdate: DateTimeOffset.UtcNow.AddDays(7),
    hashAlgorithm: HashAlgorithmName.SHA256,
    rsaSignaturePadding: null,  // Für PQ nicht relevant
    mode: CryptoMode.Hybrid
);

// CRL speichern
File.WriteAllBytes("intermediate-ca.crl", crlBytes);

// CRL zu PEM konvertieren
var crlPem = ctx.ToPem(crlBytes, "X509 CRL");
File.WriteAllText("intermediate-ca.crl.pem", crlPem);

Console.WriteLine("CRL erstellt:");
Console.WriteLine($"  Einträge: {crlBuilder.Entries.Count}");
Console.WriteLine($"  CRL Number: 1000");
Console.WriteLine($"  Next Update: {DateTimeOffset.UtcNow.AddDays(7):yyyy-MM-dd}");
</code>

----

===== Aggiornare CRL da CRL esistente =====

<code csharp>
public class CrlUpdater
{
    public byte[] UpdateCrl(
        byte[] existingCrl,
        X509Certificate2 caCert,
        AsymmetricAlgorithm caKey,
        IEnumerable<CrlEntry>? newEntries = null)
    {
        using var ctx = PqCryptoContext.Initialize();

        // Bestehende CRL parsen
        var parsedCrl = ctx.ParseCrl(existingCrl);

        // Neuen Builder mit bestehenden Einträgen
        var builder = new CertificateRevocationListBuilder();

        foreach (var entry in parsedCrl.Entries)
        {
            builder.AddEntry(entry.SerialNumber, entry.RevocationTime, entry.Reason);
        }

        // Neue Einträge hinzufügen
        if (newEntries != null)
        {
            foreach (var entry in newEntries)
            {
                builder.AddEntry(entry.SerialNumber, entry.RevocationTime, entry.Reason);
            }
        }

        // Neue CRL-Nummer (inkrementiert)
        var newCrlNumber = parsedCrl.CrlNumber + 1;

        // Neue CRL erstellen
        return builder.Build(
            issuerCertificate: caCert,
            crlNumber: newCrlNumber,
            nextUpdate: DateTimeOffset.UtcNow.AddDays(7),
            hashAlgorithm: HashAlgorithmName.SHA256,
            mode: CryptoMode.Hybrid
        );
    }
}
</code>

----

===== CRL Extensions =====

<code csharp>
// CRL mit Extensions
var crlBuilder = new CertificateRevocationListBuilder();

// CRL Extensions
crlBuilder.AddExtension(
    oid: "2.5.29.20",  // CRL Number
    critical: false,
    value: BuildCrlNumberExtension(1001)
);

crlBuilder.AddExtension(
    oid: "2.5.29.35",  // Authority Key Identifier
    critical: false,
    value: BuildAkiExtension(caCert)
);

crlBuilder.AddExtension(
    oid: "2.5.29.28",  // Issuing Distribution Point
    critical: true,
    value: BuildIdpExtension(
        distributionPoint: "http://crl.example.com/intermediate.crl",
        onlyContainUserCerts: true
    )
);

// Entry Extensions (pro widerrufenes Zertifikat)
crlBuilder.AddEntry(
    serialNumber: revokedSerial,
    revocationTime: DateTimeOffset.UtcNow,
    reason: X509RevocationReason.KeyCompromise,
    extensions: new X509ExtensionCollection
    {
        // Invalidity Date (wann tatsächlich kompromittiert)
        BuildInvalidityDateExtension(compromiseDate),
        // Certificate Issuer (falls Indirect CRL)
        BuildCertificateIssuerExtension(certIssuerDn)
    }
);
</code>

----

===== Motivi di revoca (RFC 5280) =====

^  Codice  ^  Motivo  ^  Descrizione  ^
| 0 | unspecified | Nessun motivo specifico |
| 1 | keyCompromise | Chiave compromessa |
| 2 | cACompromise | CA compromessa |
| 3 | affiliationChanged | Affiliazione modificata |
| 4 | superseded | Sostituito da nuovo certificato |
| 5 | cessationOfOperation | Attività cessata |
| 6 | certificateHold | Sospeso temporaneamente |
| 8 | removeFromCRL | Rimuovere da CRL (annullare sospensione) |
| 9 | privilegeWithdrawn | Privilegio revocato |
| 10 | aACompromise | Attribute Authority compromessa |

----

===== Configurare CRL Distribution Point =====

<code csharp>
// Zertifikat mit CDP ausstellen
var cert = ctx.IssueCertificate(
    csr,
    issuerCert: caCert,
    issuerKey: caKey,
    extensions: new ExtBuilder()
        .CrlDistributionPoint(
            uri: "http://crl.example.com/intermediate.crl",
            ldapUri: "ldap://ldap.example.com/cn=Intermediate-CA,o=Example,c=DE?certificateRevocationList"
        )
        .Build()
);
</code>

----

===== Requisiti CRL specifici per settore =====

^  Settore  ^  Max. nextUpdate  ^  Formato  ^  Distribuzione  ^
| **WebPKI** | 7 giorni | DER | HTTP |
| **Enterprise** | 24 ore | DER/PEM | HTTP, LDAP |
| **Energia/SCADA** | 30 giorni | DER | Offline |
| **Sanità** | 24 ore | DER | HTTP |

<WRAP round tip>
**Best Practice:** Aggiornare la CRL prima di nextUpdate (50-75% della durata di validità).
</WRAP>

----

===== Scenari correlati =====

^  Relazione  ^  Scenario  ^  Descrizione  ^
| **Alternativa** | [[.:ocsp_responder|6.2 OCSP Responder]] | Verifica online |
| **Estensione** | [[.:delta_crl|6.3 Delta-CRL]] | Aggiornamenti incrementali |
| **Prerequisito** | [[.:zertifikat_widerrufen|6.4 Revocare certificato]] | Processo di revoca |

----

<< [[.:start|← Panoramica revoca]] | [[it:int:pqcrypt:szenarien:start|↑ Scenari]] | [[.:ocsp_responder|6.2 OCSP Responder →]] >>

{{tag>scenario revoca crl revocation pki}}

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