Working with SSL certificates on Azure and IIS7

Recently I’ve had cause to set-up a SSL secured site on Windows Azure.  Never having worked with SSL before I thought I’d quickly blog about a few of the gotcha’s I experienced along the way.

You are here

Before I started, naturally, and as usual, I hit Google to find all Azure SSL wisdom.  I found a great post by SondreB – Windows Azure: Secure Site with SSL certificate.  This is a great guide and I urge you to follow it, however, as an SSL amateur I found it had a couple of gaps.  Which I’ll expand on below.

.crt != .pfx

First off Azure expects to work with SSL certificates that are saved in the .pfx format.  However, when you request a SSL from an authority like Verisign, it comes in .crt format.  These are both valid X.509 formats but you need to convert the cert you receive from Verisign to a format readily understood by Azure.

Gotcha #1 – you have to create the Certificate Request from the same PC that you plan to generate the .pfx from.  So if you were working with on-prem IIS you’d generate the Certificate Request from the IIS server that you’re planning to host the app on.  However, when working with Azure do all SSL work on your dev PC that has both Visual Studio and IIS7 installed.

Creating a Certificate Request

Open IIS7 locally and double-click Server Certificates.  In the left hand side you should have the option to Create Certificate Request.  Complete the wizard as SondreB advises and save the .txt file to your local PC.  If you open the .txt file you’ll see it contains a Certificate Request cryptographic key.

Creating a SSL Certificate

Verisign have a great free service to allow you to create multiple temporary SSL certificate which lasts for 30 days.  Which is great, as if like me, you’ll probably create one or two before you get the process down.  You can purchase a real one once you are happy you’ve got everything worked out.

Complete the contact form, then you’ll be invited to input your Certificate Request.  Ensure you select Microsoft and IIS7 in the Platform details section, then paste in your Certificate Request key.  Complete the process and you’ll be emailed your certificate shortly afterwards.

Importing your SSL Certificate

The email from Verisign will contain another cryptographic key.  Copy it out of the email and paste it into a new file, ensuring you give it a .crt extension – ie myVerisignCert.crt.

Gotcha #2 – SondreB states in the blog you can right-click the .crt and import it into your PC.  This didn’t work for me.  Luckily, however, there’s a free tool that did.  Download the DigiCertUtil.exe and run it.  You should now be able to import the .crt into your certificate store on your local PC (nb – ensure you run as admin or you won’t be able to import the cert).

Export the .pfx

With your .crt successfully imported, you can export it in .pfx format again as SondreB outlines.  You can then simply upload the .pfx to the appropriate host in Azure.  The .crt should now also be available to your Azure cloud project within Visual Studio and again can be imported, as outlined by SondreB.

You looking at my endpoints?

The final gotcha to be aware of, is that you can’t VIP Swap a project that has more endpoints than the one you’re attempting to replace.  If the solution you’re running only has the standard http endpoint you’ll have to delete the running live instance to swap in the package with the additional 443 endpoint.

This could be a major pain, as you’ll be assigned a new IP address etc, and in my experiments it’ll take around 30 minutes for your site to appear on line again, as the CName record seems to take a while to catch up to the new IP address.

So if you know you’re working on a site that will be SSL enabled it would be a good idea to create the 443 endpoint from the start, not at the end of the project, as I discovered.

Otherwise that should be it, SSL happiness awaits