Certificate Management

Compact examples for certificate management. → Details: Management Scenarios

var caCert = new X509Certificate2("intermediate-ca.pfx", "password");
var oldCert = new X509Certificate2("server.pfx", "password");
 
var privateKey = oldCert.GetECDsaPrivateKey();
 
var request = new CertificateRequest(
    oldCert.SubjectName, (ECDsa)privateKey, HashAlgorithmName.SHA384);
 
// Copy extensions (except SKI)
foreach (var ext in oldCert.Extensions)
    if (ext.Oid?.Value != "2.5.29.14")
        request.CertificateExtensions.Add(ext);
 
// New serial number
var serial = new byte[20];
RandomNumberGenerator.Fill(serial);
serial[0] &= 0x7F;
 
var renewedCert = request.Create(caCert,
    DateTimeOffset.UtcNow, DateTimeOffset.UtcNow.AddYears(1), serial);

→ Details: Renewal

var oldCert = new X509Certificate2("server.crt");
using var newKey = ECDsa.Create(ECCurve.NamedCurves.nistP384);
 
var request = new CertificateRequest(
    oldCert.SubjectName, newKey, HashAlgorithmName.SHA384);
 
// Copy SANs and EKU
if (oldCert.Extensions["2.5.29.17"] is { } san)
    request.CertificateExtensions.Add(san);
if (oldCert.Extensions["2.5.29.37"] is { } eku)
    request.CertificateExtensions.Add(eku);
 
// Create new certificate, revoke old one!

→ Details: Re-Key

var caCert = new X509Certificate2("intermediate-ca.pfx", "password");
var crlBuilder = new CertificateRevocationListBuilder();
 
crlBuilder.AddEntry(
    serialNumber: new byte[] { 0x01, 0x23, 0x45 },
    revocationTime: DateTimeOffset.UtcNow,
    reason: X509RevocationReason.KeyCompromise);
 
var crl = crlBuilder.Build(caCert,
    crlNumber: BitConverter.GetBytes(1L),
    nextUpdate: DateTimeOffset.UtcNow.AddDays(7),
    HashAlgorithmName.SHA384);
 
File.WriteAllBytes("intermediate.crl", crl);

→ Details: Create CRL

Before Expiry (30 days):

• Plan renewal
• Decide renewal or re-key

On Compromise:

• Immediate re-key (new key!)
• Revoke old certificate
• Update CRL

« <- Quick Reference | -> Management Scenarios (Details) »

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