Convert certificate and private key to .PFX programmatically in C #

Question

I have the output of a .cer file from a successful LetsEncrypt certificate request.

I have an original private key used to create a certificate signing request (CSR) for LetsEncrypt.

Now we need to programmatically merge these two files into a PFX package for IIS using .NET

Since we are trying to do this programmatically, pvk2pfx is not practical, and we would like to avoid openssl if possible.

However, for demonstration, we are trying to reproduce this function, but using CS.NET instead of pvk2pfx: pvk2pfx.exe -pvk Server.pvk -spc Server.cer -pfx Server.pfx

I have exhaustively researched, and here are the possibilities that I see:

One method seems to use X509Certificate2 something like:

// Import the certficate X509Certificate2 cert = new X509Certificate2("c:\\cert.cer"); // Import the private key X509Certificate2 cert = new X509Certificate2("c:\\key.pvk"); // Or import the private key - Alternative method X509DecryptString(token, @"c:\CA.pvk", "mypassword"); // Export the PFX file certificate.Export(X509ContentType.Pfx, "YourPassword"); File.WriteAllBytes(@"C:\YourCert.pfx", certificateData); 

Here are some other methods, but they all seem to skip the private key part or require pvk2pfx.exe

Convert from certificate file to pfx file

How to create X509Certificate2 programmatically? http://www.wiktorzychla.com/2012/12/how-to-create-x509certificate2.html

Select, create and find X509 certificates: http://www.wou.edu/~rvitolo06/WATK/Demos/HPCImageRendering/code/ImageRendering/AppConfigure/CertHelper.cs

It is not possible to export the generated private key certificate to a byte array. Unable to export generated private key certificate to byte array in .net 4.0 / 4.5

How to programmatically import pfx with a certificate chain into a certificate store. stack overflow

Import the .cer and .pvk certificate files programmatically in C # for use with netsh http add sslcert https://gist.github.com/BrandonLWhite/235fa12247f6dc827051

The way to convert cer to pfx cert https://gist.github.com/domgreen/988684

Any help greatly appreciated :-)

---

EDIT 1

CryptoGuy offered us this link: https://gist.github.com/BrandonLWhite/235fa12247f6dc827051

Does this mean something like this would be good?

Are parts of a CSP needed?

Thanks!

 using System.Security.Cryptography.X509Certificates; using System.Security.Cryptography; var PublicKey = AssemblyUtility.GetEmbeddedFileAsByteArray("Cert.cer"); var PrivateKey = AssemblyUtility.GetEmbeddedFileAsByteArray("PrivateKey.pvk"); var certificate = new X509Certificate2(PublicKey, string.Empty, X509KeyStorageFlags.MachineKeySet | X509KeyStorageFlags.PersistKeySet | X509KeyStorageFlags.Exportable); var cspParams = new CspParameters { ProviderType = 1, Flags = CspProviderFlags.UseMachineKeyStore, KeyContainerName = Guid.NewGuid().ToString().ToUpperInvariant() }; var rsa = new RSACryptoServiceProvider(cspParams); rsa.ImportCspBlob(ExtractPrivateKeyBlobFromPvk(PrivateKey)); rsa.PersistKeyInCsp = true; certificate.PrivateKey = rsa; certificate.Export(X509ContentType.Pfx, "YourPassword"); File.WriteAllBytes(@"C:\YourCert.pfx", certificateData); 

Answer 1

CryptoGuy's answer was really helpful and pointed us in the right direction.

We were still trying to import the DER binary, but this code fixed:

 var oc = OpenSSL.X509.X509Certificate.FromDER(bio); 

These pages were useful:

https://github.com/openssl-net/openssl-net/blob/master/ManagedOpenSsl/X509/X509Certificate.cs

https://msdn.microsoft.com/en-us/library/system.security.cryptography.x509certificates.x509certificate2.rawdata

Thank you all for your help :)