Category: Issue Certificates
Complexity: * (Medium-High)
Prerequisites: CSR available, Intermediate CA
Estimated Time: 10-15 minutes </WRAP> —- ===== Description ===== This scenario describes issuing a TLS server certificate by an Intermediate CA. The certificate enables HTTPS encryption for web servers, APIs, and other TLS-protected services. What is created: * X.509 v3 server certificate * Signed with ML-DSA-65 (Post-Quantum) * Extensions for TLS server —- ===== Workflow ===== <mermaid> flowchart LR CSR[Load CSR] –> VERIFY[Verify CSR] VERIFY –> EXT[Set extensions] EXT –> SERIAL[Generate serial] SERIAL –> SIGN[Sign with CA] SIGN –> EXPORT[Export as PEM] style SIGN fill:#e8f5e9 </mermaid> —- ===== Code Example (C#) ===== <code csharp> using WvdS.Security.Cryptography.X509Certificates.Extensions.PQ; using var ctx = PqCryptoContext.Initialize(); Load Intermediate CA var caCert = ctx.LoadCertificate(„intermediate-ca.crt.pem“); var caKey = ctx.LoadPrivateKey(„intermediate-ca.key.pem“, „CaPassword!“); Load and verify CSR var csr = ctx.LoadCertificateRequest(File.ReadAllText(„server.csr.pem“)); if (!csr.VerifySignature()) throw new CryptographicException(„Invalid CSR signature“); Issue server certificate var serverCert = ctx.IssueCertificate( csr, issuerCert: caCert, issuerKey: caKey, serialNumber: ctx.GenerateSerialNumber(), validDays: 365, 1 year extensions: new ExtBuilder() Basic Constraints: Not a CA .BasicConstraints(ca: false, critical: true) Key Usage for TLS .KeyUsage(KeyUsageFlags.DigitalSignature | KeyUsageFlags.KeyEncipherment, critical: true) Extended Key Usage: Server Auth .ExtendedKeyUsage(ExtKeyUsage.ServerAuth) Subject Key Identifier .SubjectKeyIdentifier(csr.PublicKey) Authority Key Identifier .AuthorityKeyIdentifier(caCert) CRL Distribution Point .CrlDistributionPoint(„http://crl.example.com/intermediate.crl“) OCSP Responder .AuthorityInfoAccess( ocspUrl: „http://ocsp.example.com“, caIssuersUrl: „http://ca.example.com/intermediate.crt“ ) .Build() ); Save serverCert.ToPemFile(„server.crt.pem“); Create certificate chain var chain = $„{serverCert.ToPem()}\n{caCert.ToPem()}“; File.WriteAllText(„server-chain.pem“, chain); Console.WriteLine(„Server certificate issued:“); Console.WriteLine($„ Subject: {serverCert.Subject}“); Console.WriteLine($„ Issuer: {serverCert.Issuer}“); Console.WriteLine($„ Serial: {serverCert.SerialNumber}“); Console.WriteLine($„ Valid until: {serverCert.NotAfter:yyyy-MM-dd}“); </code> —- ===== Extensions for Server Certificates ===== ^ Extension ^ Value ^ Critical ^ Description ^ | Basic Constraints | CA=false | Yes | Not a CA certificate | | Key Usage | digitalSignature, keyEncipherment | Yes | TLS handshake | | Extended Key Usage | serverAuth | No | Server authentication | | Subject Key Identifier | Hash(PublicKey) | No | Key ID | | Authority Key Identifier | CA-SKI | No | Issuer reference | | Subject Alt Name | DNS names | No | Taken from CSR | | CRL Distribution Points | URL | No | Revocation checking | | Authority Info Access | OCSP, CA Issuers | No | Validation helpers | —- ===== Industry-Specific Validity Periods ===== ^ Industry ^ Validity ^ Rationale ^ | Standard IT | 1 year (365 days) | CA/Browser Forum Maximum | | Energy/SCADA | 3-5 years | Long maintenance cycles | | Healthcare | 1-2 years | Compliance requirements | | Automotive | 2-3 years | Vehicle lifecycle |