Data validation and encryption signatures

ivan37

I have a project where I need to log logins (time of day, user that is logged in, etc) in such a way that I can't add new records, change existing records, etc. Then, someone else (the auditor) has to be able to view the records and validate that they are correct.

So far I've come up with this: I create an encoded signature of the data incorporating an additional "secret code" that is hard-coded into the php file by the auditor. This encoded signature field is added to the database along with the rest of the login data. The PHP script that does all the logging is then encoded by Zend encoder (or equivalent) by the auditor and given to me so that I can't get at the secret code. In this way, I cannot add or change records because I cannot create the corresponding encoded signature without the code. The auditor can validate the data by putting the secrect code together with the data and comparing the resulting signature with the signature attached to the record.

This method works, but there are problems. For example, I can't change any of the surrounding code without having the auditor re-enter the secret code and encode the script.

Can people please direct me to any other ways of doing this, signature algorithms that might work better than the 128-bit md5, and any other advice you might give me?

Many Thanks

HalfaBee

I know this is a bit stupid, but is the auditor a php programmer?
You could write a class to add the data with the encoded info and get that zend encoded and then your code would be seperate from the encoding.

MD5 is probably as secure as you could get as long as the password is not a dictionary word.
To crack a 10 character random password would take hundreds of years.

HalfaBee

ivan37

Originally posted by HalfaBee
You could write a class to add the data with the encoded info and get that zend encoded and then your code would be seperate from the encoding.

That would be much more ideal, but the problem there is that the "OK, this is a valid login" logic has to be attached (at least I think) to the generation of the log or I could create as many logins as I want by creating a separate script that used the encoding class.