uses GenerateSelfSignedCertificate to generate an SSL cert

GenerateSelfSignedCertificate.cs

public unsafe X509Certificate2 GenerateSelfSignedCertificate(PrivateKey privateKey, X500DistinguishedName dn, HashAlgorithm signatureAlgorithm, string[] dnsNames, IPAddress[] ipAddresses = null, DateTime? notBefore = null, DateTime? notAfter = null)
{
  fixed (byte* dnPtr = dn.RawData)
  {
    var blob = new NATIVE_CRYPTOAPI_BLOB
    {
        cbData = (uint)dn.RawData.Length,
        pbData = dnPtr
    };
    var signatureAlgorithmIdentifier = new CRYPT_ALGORITHM_IDENTIFIER
    {
        pszObjId = HashAlgorithmToSignatureAlgorithm(privateKey, signatureAlgorithm)
    };
    using (var extensions = new MarshalX509ExtensionCollection())
    {
        using (extensions.Freeze())
        {
            var usage = X509KeyUsageFlags.DigitalSignature;
            if (privateKey.AlgorithmGroup == AlgorithmGroup.RSA)
            {
                //Key encipherment is not valid for DSA/ECDSA
                usage |= X509KeyUsageFlags.KeyEncipherment;
            }
            extensions.Add(new X509BasicConstraintsExtension(false, false, 0, true));
            extensions.Add(new X509KeyUsageExtension(usage, true));
            extensions.Add(new X509EnhancedKeyUsageExtension(new OidCollection { new Oid(OIDs.EKU_SERVER) }, false));
            extensions.Add(new X509SubjectAlternativeNameExtension(DnsAltNamesFromArray(dnsNames, ipAddresses ?? new IPAddress[0]), false));

            // extensions.Add(new X509BasicConstraintsExtension(true, true, 1, true));
            // extensions.Add(new X509KeyUsageExtension(X509KeyUsageFlags.CrlSign | X509KeyUsageFlags.KeyCertSign, true));
            // extensions.Add(new X509EnhancedKeyUsageExtension(new OidCollection { new Oid(OIDs.EKU_SERVER) }, false));

            using (var publicKey = privateKey.ToPublicKey())
            {
                using (var sha1 = new SHA1CryptoServiceProvider())
                {
                    var pubKeyHash = sha1.ComputeHash(publicKey.Key);
                    extensions.Add(new X509SubjectKeyIdentifierExtension(pubKeyHash, false));
                    extensions.Add(new X509AuthorityKeyIdentifierExtension(pubKeyHash, null));
                }
            }
        }
        var certExtensions = extensions.Extensions;
        var keyProvInfo = new CRYPT_KEY_PROV_INFO
        {
            cProvParam = 0,
            dwKeySpec = privateKey.KeySpec,
            dwProvType = privateKey.Handle.IsNCryptKey ? ProviderType.CNG : ProviderType.PROV_RSA_AES,
            pwszProvName = privateKey.ProviderName,
            dwFlags = 0,
            pwszContainerName = privateKey.Name
        };
        var beginning = new SYSTEMTIME(notBefore ?? DateTime.UtcNow.AddHours(-1));
        var expiration = new SYSTEMTIME(notAfter ?? DateTime.UtcNow.AddHours(-1).AddYears(30));
        var certContext = Crypt32.CertCreateSelfSignCertificate(privateKey.Handle, ref blob, SelfSignFlags.NONE, ref keyProvInfo, ref signatureAlgorithmIdentifier, beginning, expiration, ref certExtensions);
        if (certContext == IntPtr.Zero)
        {
            throw new Win32Exception(Marshal.GetLastWin32Error());
        }
        return new X509Certificate2(certContext);
    }
  }
}