Re: [GD-General] serial numbers

[J C L. <cl...@ka...>]

On Tue, 27 May 2003 01:25:20 +0200 
iso  <iso-8859-1> wrote:

> I'd like to know which algoritms are usually used to generate and
> validate the keys. They keys should look like random, and I would like
> to include the product and user name in a non-obvious way. So that,
> given the product and the user, I should be able to validate the given
> key.

Typical forms I've seen are a one-way hash ala MD5 of the public data,
along with a secret.  The resultant string (often with another secret)
is then digitally signed with the resultant string, sometimes with a CRC
or other padding data appended..  The application then verifies the
signature to check that the key is of valid form, and the central site
can check that the key is legit.  

Other variants have (some of) the public data encoded in easily
reversible fashion in the string so that entering the key in the app
"magically" causes other fields to be populated.

-- 
J C Lawrence                
---------(*)                Satan, oscillate my metallic sonatas. 
cl...@ka...               He lived as a devil, eh?		  
http://www.kanga.nu/~claw/  Evil is a name of a foeman, as I live.