Extra check column for application

[Patten]

Hey,

anybody out there having ideas/thoughts/experiences around following concept:

I want to develop an application using a database. Since databases are open for anybody having the appropiate rights and connection software, I want to be sure nobody changes data in certain tables manually, but uses always the application. I would like to add an extra column in these tables which is updated by the application each time an insert/update happens. The value of this column should be calculated by a certain "secret" formula not known to the users of the application. So if they do things manually they do not know which value to use for this extra column and in that way these manually changed records can be found. Anybody done such a thing and if so what are the experiences? Do you have tips for a good formula?

 

[CajunCenturion]

Yes, I've use a similar technique to detect that database updates to critical fields occured from outside the base application. In this case, there were certain types of relationships that were established and verified, and were best handled in non-readable code. So when an external change was detected, the system could automatically update these other relationships. This was not a security issue, but rather more of an integrity issue.

Whether or not this approach would work for you, in large part, depends on why you want this type of update check. If it's a security issue, then you might want to use encryption on that table/column to begin with, or prevent access to the database though passwords and such.

As far as the algorithm is concerned, are you interested only in detection, or is correction also a factor to be considered. In any event, I would start with the various check digit algorithms (mod10, mod11, etc).

Good Luck
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