Blogger OpenID support commenting for all blogs hosted. This means that if you have an OpenID setup, you can ensure that all comments by you on blogger blogs are genuine. No one can spoof you when commenting on a Blogger blog. This assumes two things - you use OpenID for commenting and others know that only OpenID based comments are written by you!

Another advantage is that your URL can be automatically inserted in the comment. For this to happen, use your blog or site as your OpenID identity. This doesn’t mean that you have to have your own OpenID provider. You can use other providers such as Verisign or Technorati and then delegate to it from your blog! This means that you can change your provider without affecting your identity (your blog).

Now it is not necessary that you should use a third party OpenID provider. You can be your own OpenID provider! For details, check Setting up OpenID.

How does OpenID work?

When you use OpenID, there are 3 players. You (Y), OpenID service provider(P) and the site you are trying to login(T) using OpenID. When you indicate your OpenID identity at the T, it will handshake with P to get a secret key. Then you are re-directed to the P’s Web site to login. After login, the same secret key is prepared using your password by P and it returns it to T. Now T can compare this with the original secret key. If they are same, that means you did authenticate at the P!  Simple isn’t it?