====== Scenario 3.5: Issue Wildcard Certificate ======

<WRAP round info>
**Category:** [[.:start|Issue Certificates]] \\
**Complexity:** **** (High) \\
**Prerequisites:** Domain control, Intermediate CA \\
**Estimated Time:** 15-20 minutes
</WRAP>

----

===== Description =====

This scenario describes issuing a **wildcard certificate** (''*.example.com''). Wildcard certificates secure all subdomains of a domain with a single certificate.

**Advantages:**
  * One certificate for all subdomains
  * Easier management
  * More cost-effective

**Disadvantages:**
  * Higher risk if compromised
  * Does not cover root domain
  * Only one level

----

===== Wildcard Rules =====

^  Pattern  ^  Covers  ^  Does NOT cover  ^
| ''*.example.com'' | www.example.com, api.example.com | example.com, sub.api.example.com |
| ''*.api.example.com'' | v1.api.example.com | api.example.com |

<WRAP round important>
**Important:** ''*.example.com'' does NOT cover ''example.com'' (without subdomain)! Always add both as SAN.
</WRAP>

----

===== Code Example (C#) =====

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

using var ctx = PqCryptoContext.Initialize();

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

// Key pair for wildcard
using var wildcardKey = ctx.GenerateKeyPair(PqAlgorithm.MlDsa65);

var dn = new DnBuilder()
    .AddCN("*.example.com")
    .AddO("Example GmbH")
    .AddC("DE")
    .Build();

// Create CSR
var csr = ctx.CreateCertificateRequest(
    wildcardKey, dn,
    new ExtBuilder()
        // Wildcard + root domain
        .SubjectAlternativeName(new[] {
            "dns:*.example.com",
            "dns:example.com"
        })
        .Build()
);

// Issue wildcard certificate
var wildcardCert = ctx.IssueCertificate(
    csr,
    issuerCert: caCert,
    issuerKey: caKey,
    serialNumber: ctx.GenerateSerialNumber(),
    validDays: 365,
    extensions: new ExtBuilder()
        .BasicConstraints(ca: false, critical: true)
        .KeyUsage(KeyUsageFlags.DigitalSignature | KeyUsageFlags.KeyEncipherment)
        .ExtendedKeyUsage(ExtKeyUsage.ServerAuth)
        .SubjectKeyIdentifier(csr.PublicKey)
        .AuthorityKeyIdentifier(caCert)
        .CrlDistributionPoint("http://crl.example.com/intermediate.crl")
        .Build()
);

wildcardCert.ToPemFile("wildcard.crt.pem");
wildcardKey.ToEncryptedPemFile("wildcard.key.pem", "SecurePassword!");
</code>

----

===== Multi-Level Wildcard =====

For multiple subdomain levels, combine multiple wildcards:

<code csharp>
.SubjectAlternativeName(new[] {
    "dns:example.com",
    "dns:*.example.com",          // www, api, app, etc.
    "dns:*.dev.example.com",      // dev1.dev, dev2.dev, etc.
    "dns:*.staging.example.com"   // staging environments
})
</code>

----

===== Security Notes =====

<WRAP round alert>
**Risks of Wildcard Certificates:**
  * Compromise affects ALL subdomains
  * Private key needed in multiple locations
  * Revocation affects all services
</WRAP>

**Best Practices:**
  * Store private key centrally (HSM)
  * Short validity (max. 1 year)
  * Separate wildcard certificates for Prod/Dev/Staging
  * Monitoring for all subdomains

----

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

^  Relationship  ^  Scenario  ^  Description  ^
| **Alternative** | [[.:server_cert|3.1 Server Certificate]] | Single certificate |
| **Alternative** | [[en:int:pqcrypt:szenarien:csr:csr_multi_san|2.3 Multi-SAN CSR]] | Explicit SANs |
| **Next Step** | [[en:int:pqcrypt:szenarien:tls:server_setup|10.1 TLS Server]] | Deployment |

----

<< [[.:smime_cert|<- 3.4 S/MIME Certificate]] | [[.:start|^ Certificates Overview]] | [[en:int:pqcrypt:szenarien:verwaltung:start|4. Manage Certificates ->]] >>

{{tag>scenario certificate wildcard subdomain tls}}

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