> In my mind the only way to guarantee is to maintain a copy yourself and check against the "original", but if you're going to do that, then what I described is

> In my mind the only way to guarantee is to maintain a copy yourself and check against the "original", but if you're going to do that, then what I described is sufficient, no? The attacker in that case could update your copy. But you have somewhat started to fix the issue. To cover the case where a bad admin has access to the DB and any copies, you need to send a hash every so often to an outside source. In this case they use clients (I'm not sure exactly how they do this). In fact you need a list of hashes one for every 100 rows for example. Re-generated the hashes and checking against an external source should detect a tamper. In the case of Bitcoin (which is extremely tamper resistant) every node operator is a validator. The hashes are stored in a merkle tree.