>>>I use a couple of fields in the users tables and do a check sum on the 2 >-- see sys(2007) in VFP help. Then do a comparison within my code to make >sure the fields have not been tampered with. If tampering detected, I >terminate the application and have the app send me a Netware message. >> >>thanks Mark - I will check it out... :) > >Sounds like a good idea...I would still run the sys(2007) return value >through a formula so it wouldn't be easy to crack for someone with the >checksum formula, or someone with FoxPro who is aware of the sys(2007) >function.... I don't see the need for reverting the checksum into original value - simply run the formula on the user's input and compare that with what's in the table, so the original value never gets written or reconstructed anywhere, as is the normal procedure with passwords and similar stuff. Another neat trick is that you don't run sys(2007) on bare user's string, but add your string before it, possibly scrambled like chr(pi()**2.89714)+prog(1) (so it doesn't appear as a constant nowhere in your code), or something equally obscure.