Register certificate to SSL port

Question

I have a windows service (running as LocalSystem) that is self-hosting an OWIN service (SignalR) and needs to be accessed over SSL.

I can set up the SSL binding on my loc

Answer 1

Here is the full code including:

• Generating certificate
• Registering ssl on port
• Running simple HTTPS server on that port

** Forgive me the quality of code. It's just a very dirty proof of concept glued form different pieces of code I found on the web and Robert Petz answer. I didn't have time to clean it up:

Remember to

• Run Visual Studio as admin (admin priveleges are requied for this code)
• Add Reference to the project: COM > TypeLibraries > CertEnroll 1.0 Type Library

Code:

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Net.Http;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using System.Threading.Tasks;
using System.Web.Http.SelfHost;
using CERTENROLLLib;

namespace SelfhostSSLProofOfConcept
{
    /// <summary>
    /// Add Reference: COM > TypeLibraries > CertEnroll 1.0 Type Library
    /// </summary>
    class Program
    {
        static void Main(string[] args)
        {
            var port = 1234;

            var certSubjectName = "Your cert subject name";
            var expiresIn = TimeSpan.FromDays(7);
            var cert = GenerateCert(certSubjectName, expiresIn);

            Console.WriteLine("Generated certificate, {0}Thumbprint: {1}{0}", Environment.NewLine, cert.Thumbprint);

            RegisterSslOnPort(port, cert.Thumbprint);
            Console.WriteLine($"Registerd SSL on port: {port}");

            var config = new HttpSelfHostConfiguration($"https://localhost:{port}");

            var server = new HttpSelfHostServer(config, new MyWebAPIMessageHandler());
            var task = server.OpenAsync();
            task.Wait();

            Process.Start($"https://localhost:{port}"); // automatically run browser

            Console.WriteLine($"Web API Server has started at https://localhost:{port}");
            Console.ReadLine();
        }

        private static void RegisterSslOnPort(int port, string certThumbprint)
        {
            var appId = Guid.NewGuid();
            string arguments = $"http add sslcert ipport=0.0.0.0:{port} certhash={certThumbprint} appid={{{appId}}}";
            ProcessStartInfo procStartInfo = new ProcessStartInfo("netsh", arguments);

            procStartInfo.RedirectStandardOutput = true;
            procStartInfo.UseShellExecute = false;
            procStartInfo.CreateNoWindow = true;

            var process = Process.Start(procStartInfo);
            while (!process.StandardOutput.EndOfStream)
            {
                string line = process.StandardOutput.ReadLine();
                Console.WriteLine(line);
            }

            process.WaitForExit();
        }

        public static X509Certificate2 GenerateCert(string certName, TimeSpan expiresIn)
        {
            var store = new X509Store(StoreName.Root, StoreLocation.LocalMachine);
            store.Open(OpenFlags.ReadWrite);
            var existingCert = store.Certificates.Find(X509FindType.FindBySubjectName, certName, false);
            if (existingCert.Count > 0)
            {
                store.Close();
                return existingCert[0];
            }
            else
            {
                var cert = CreateSelfSignedCertificate(certName, expiresIn);
                store.Add(cert);

                store.Close();
                return cert;
            }
        }

        /// <summary>
        /// Add Reference: COM > TypeLibraries > CertEnroll 1.0 Type Library
        /// source: https://stackoverflow.com/a/13806300/594354
        /// </summary>
        /// <param name="subjectName"></param>
        /// <returns></returns>
        public static X509Certificate2 CreateSelfSignedCertificate(string subjectName, TimeSpan expiresIn)
        {
            // create DN for subject and issuer
            var dn = new CX500DistinguishedName();
            dn.Encode("CN=" + subjectName, X500NameFlags.XCN_CERT_NAME_STR_NONE);

            // create a new private key for the certificate
            CX509PrivateKey privateKey = new CX509PrivateKey();
            privateKey.ProviderName = "Microsoft Base Cryptographic Provider v1.0";
            privateKey.MachineContext = true;
            privateKey.Length = 2048;
            privateKey.KeySpec = X509KeySpec.XCN_AT_SIGNATURE; // use is not limited
            privateKey.ExportPolicy = X509PrivateKeyExportFlags.XCN_NCRYPT_ALLOW_PLAINTEXT_EXPORT_FLAG;
            privateKey.Create();

            // Use the stronger SHA512 hashing algorithm
            var hashobj = new CObjectId();
            hashobj.InitializeFromAlgorithmName(ObjectIdGroupId.XCN_CRYPT_HASH_ALG_OID_GROUP_ID,
                ObjectIdPublicKeyFlags.XCN_CRYPT_OID_INFO_PUBKEY_ANY,
                AlgorithmFlags.AlgorithmFlagsNone, "SHA512");

            // add extended key usage if you want - look at MSDN for a list of possible OIDs
            var oid = new CObjectId();
            oid.InitializeFromValue("1.3.6.1.5.5.7.3.1"); // SSL server
            var oidlist = new CObjectIds();
            oidlist.Add(oid);
            var eku = new CX509ExtensionEnhancedKeyUsage();
            eku.InitializeEncode(oidlist);

            // Create the self signing request
            var cert = new CX509CertificateRequestCertificate();
            cert.InitializeFromPrivateKey(X509CertificateEnrollmentContext.ContextMachine, privateKey, "");
            cert.Subject = dn;
            cert.Issuer = dn; // the issuer and the subject are the same
            cert.NotBefore = DateTime.Now;
            // this cert expires immediately. Change to whatever makes sense for you
            cert.NotAfter = DateTime.Now.Add(expiresIn);
            cert.X509Extensions.Add((CX509Extension)eku); // add the EKU
            cert.HashAlgorithm = hashobj; // Specify the hashing algorithm
            cert.Encode(); // encode the certificate

            // Do the final enrollment process
            var enroll = new CX509Enrollment();
            enroll.InitializeFromRequest(cert); // load the certificate
            enroll.CertificateFriendlyName = subjectName; // Optional: add a friendly name
            string csr = enroll.CreateRequest(); // Output the request in base64
            // and install it back as the response
            enroll.InstallResponse(InstallResponseRestrictionFlags.AllowUntrustedCertificate,
                csr, EncodingType.XCN_CRYPT_STRING_BASE64, ""); // no password
            // output a base64 encoded PKCS#12 so we can import it back to the .Net security classes
            var base64encoded = enroll.CreatePFX("", // no password, this is for internal consumption
                PFXExportOptions.PFXExportChainWithRoot);

            // instantiate the target class with the PKCS#12 data (and the empty password)
            return new System.Security.Cryptography.X509Certificates.X509Certificate2(
                System.Convert.FromBase64String(base64encoded), "",
                // mark the private key as exportable (this is usually what you want to do)
                System.Security.Cryptography.X509Certificates.X509KeyStorageFlags.Exportable
            );
        }
    }

    class MyWebAPIMessageHandler : HttpMessageHandler
    {
        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, System.Threading.CancellationToken cancellationToken)
        {
            var task = new Task<HttpResponseMessage>(() => {
                var resMsg = new HttpResponseMessage();
                resMsg.Content = new StringContent("Hello World!");
                return resMsg;
            });

            task.Start();
            return task;
        }
    }
}

Answer 2

Okay I found the answer:

If you are bringing in a certificate from another machine it will NOT work on the new machine. You have to create a self-signed certificate on the new machine and import it into the Local Computer's Trusted Root Certificates.

The answer is from here: How to create a self-signed certificate using C#?

For posterity's sake this is the process used to create a self signed cert (from the above referenced answer):

Import the CertEnroll 1.0 Type Library from the COM tab in your project's references

Add the following method to your code:

//This method credit belongs to this StackOverflow Answer:
//https://stackoverflow.com/a/13806300/594354
using CERTENROLLLib;

public static X509Certificate2 CreateSelfSignedCertificate(string subjectName)
{
    // create DN for subject and issuer
    var dn = new CX500DistinguishedName();
    dn.Encode("CN=" + subjectName, X500NameFlags.XCN_CERT_NAME_STR_NONE);

    // create a new private key for the certificate
    CX509PrivateKey privateKey = new CX509PrivateKey();
    privateKey.ProviderName = "Microsoft Base Cryptographic Provider v1.0";
    privateKey.MachineContext = true;
    privateKey.Length = 2048;
    privateKey.KeySpec = X509KeySpec.XCN_AT_SIGNATURE; // use is not limited
    privateKey.ExportPolicy = X509PrivateKeyExportFlags.XCN_NCRYPT_ALLOW_PLAINTEXT_EXPORT_FLAG;
    privateKey.Create();

    // Use the stronger SHA512 hashing algorithm
    var hashobj = new CObjectId();
    hashobj.InitializeFromAlgorithmName(ObjectIdGroupId.XCN_CRYPT_HASH_ALG_OID_GROUP_ID,
        ObjectIdPublicKeyFlags.XCN_CRYPT_OID_INFO_PUBKEY_ANY, 
        AlgorithmFlags.AlgorithmFlagsNone, "SHA512");

    // add extended key usage if you want - look at MSDN for a list of possible OIDs
    var oid = new CObjectId();
    oid.InitializeFromValue("1.3.6.1.5.5.7.3.1"); // SSL server
    var oidlist = new CObjectIds();
    oidlist.Add(oid);
    var eku = new CX509ExtensionEnhancedKeyUsage();
    eku.InitializeEncode(oidlist); 

    // Create the self signing request
    var cert = new CX509CertificateRequestCertificate();
    cert.InitializeFromPrivateKey(X509CertificateEnrollmentContext.ContextMachine, privateKey, "");
    cert.Subject = dn;
    cert.Issuer = dn; // the issuer and the subject are the same
    cert.NotBefore = DateTime.Now;
    // this cert expires immediately. Change to whatever makes sense for you
    cert.NotAfter = DateTime.Now; 
    cert.X509Extensions.Add((CX509Extension)eku); // add the EKU
    cert.HashAlgorithm = hashobj; // Specify the hashing algorithm
    cert.Encode(); // encode the certificate

    // Do the final enrollment process
    var enroll = new CX509Enrollment();
    enroll.InitializeFromRequest(cert); // load the certificate
    enroll.CertificateFriendlyName = subjectName; // Optional: add a friendly name
    string csr = enroll.CreateRequest(); // Output the request in base64
    // and install it back as the response
    enroll.InstallResponse(InstallResponseRestrictionFlags.AllowUntrustedCertificate,
        csr, EncodingType.XCN_CRYPT_STRING_BASE64, ""); // no password
    // output a base64 encoded PKCS#12 so we can import it back to the .Net security classes
    var base64encoded = enroll.CreatePFX("", // no password, this is for internal consumption
        PFXExportOptions.PFXExportChainWithRoot);

    // instantiate the target class with the PKCS#12 data (and the empty password)
    return new System.Security.Cryptography.X509Certificates.X509Certificate2(
        System.Convert.FromBase64String(base64encoded), "", 
        // mark the private key as exportable (this is usually what you want to do)
        System.Security.Cryptography.X509Certificates.X509KeyStorageFlags.Exportable
    );
}

For anyone else reading this answer - the code for importing the certificate from the original question should now change to the following:

var certName = "Your Cert Subject Name";
var store = new X509Store(StoreName.Root, StoreLocation.LocalMachine);
store.Open(OpenFlags.ReadWrite);
var existingCert = store.Certificates.Find(X509FindType.FindBySubjectName, certName, false);
if (existingCert.Count == 0)
{
    var cert = CreateSelfSignedCertificate(certName);
    store.Add(cert);
    RegisterCertForSSL(cert.Thumbprint);
}
store.Close();