How to create .pfx file from certificate and private key?
You will need to use openssl.
openssl pkcs12 -export -out domain.name.pfx -inkey domain.name.key -in domain.name.crt
The key file is just a text file with your private key in it.
If you have a root CA and intermediate certs, then include them as well using multiple -in params
openssl pkcs12 -export -out domain.name.pfx -inkey domain.name.key -in domain.name.crt -in intermediate.crt -in rootca.crt
You can install openssl from here: openssl
If you're looking for a Windows GUI, check out DigiCert. I just used this and it was fairly simple.
Under the SSL tab, I first Imported the Certificate. Then once I selected the Certificate I was able to export as a PFX, both with and without a keyfile.
https://www.digicert.com/util
The Microsoft Pvk2Pfx command line utility seems to have the functionality you need:
Pvk2Pfx (Pvk2Pfx.exe) is a command-line tool copies public key and private key information contained in .spc, .cer, and .pvk files to a Personal Information Exchange (.pfx) file.
http://msdn.microsoft.com/en-us/library/windows/hardware/ff550672(v=vs.85).aspx
Note: if you need/want/prefer a C# solution, then you may want to consider using the http://www.bouncycastle.org/ api.
You do NOT need openssl or makecert or any of that. You also don't need the personal key given to you by your CA. I can almost guarantee that the problem is that you expect to be able to use the key and cer files provided by your CA but they aren't based on "the IIS way". I'm so tired of seeing bad and difficult info out here that I decided to blog the subject and the solution. When you realize what's going on and see how easy it is, you will want to hug me :)
SSL Certs for IIS with PFX once and for all - SSL and IIS Explained - http://rainabba.blogspot.com/2014/03/ssl-certs-for-iis-with-pfx-once-and-for.html
Use IIS "Server Certificates" UI to "Generate Certificate Request" (the details of this request are out of the scope of this article but those details are critical). This will give you a CSR prepped for IIS. You then give that CSR to your CA and ask for a certificate. Then you take the CER/CRT file they give you, go back to IIS, "Complete Certificate Request" in the same place you generated the request. It may ask for a .CER and you might have a .CRT. They are the same thing. Just change the extension or use the . extension drop-down to select your .CRT. Now provide a proper "friendly name" (*.yourdomain.com, yourdomain.com, foo.yourdomain.com, etc..) THIS IS IMPORTANT! This MUST match what you setup the CSR for and what your CA provided you. If you asked for a wildcard, your CA must have approved and generated a wildcard and you must use the same. If your CSR was generated for foo.yourdomain.com, you MUST provide the same at this step.
I created .pfx file from .key and .pem files.
Like this openssl pkcs12 -inkey rootCA.key -in rootCA.pem -export -out rootCA.pfx