PKCS

The PKCS#12 specifies a portable format for storing and transporting certificates, private keys, and miscellaneous secrets. It is the preferred format for many certificate handling operations and is supported by most browsers and recent releases of the Windows family of operating systems. It has the advantage of being able to store the certificate and corresponding key, root certificate, and any other certificates in the chain in a single file.

http://sourceforge.net/projects/openssl-net/?source=dlp

http://support.citrix.com/article/CTX106630

https://www.simple-talk.com/dotnet/.net-framework/beginning-with-digital-signatures-in-.net-framework/