how to force windows to report a false hard disk serial number?

[JMI]

Now I understand better what you are trying to do. You have a server and you are apparently trying to prevent "non-registered" users of some software you are selling or users who you don't know from accessing your server?

If that is correct, you are attempting to prevent someone without the proper "code" from gaining access to the server and you want to use the HD serial number as part of the authentication process. The next question is "WHY"? By that question, I only mean that the encryption of the HD serial isn't necessarily any more or less secure that an excryption made from some other conbination of things; such as username, password, secret question, answer to secret question etc. There are many free code segments already available on the net which will provide you with an MD5 encryption of those things. If you want, I will post a link to one that is a GPL free license and is currently used by Yahoo for their security system for their servers.

One of the things you need to consider is how you will authenticate the users if they "lose" their password. If your system is dependent on their HD hash, then they could only access your server from one particular machine. No access would be possible, without cracking the access code, from any other location and if the user's HD crashed and had to be replaced, they could never "prove" they were the legitimate user of your server or software.

I believe you need to explain what you are trying to accomplish more clearly and maybe we can help more.

Regards,