[Cryptography] The Laws (was the principles) of secure information systems design

[Bob Wilson]

> Law 2: If it isn't stored it can't be stolen
Sounds "obviously" true, but as a mathematician I know that when I say 
something is "obvious" other mathematicians will take it to mean I need 
it to be true but I can't remember how to prove it. (There are lots of 
mathematician's jokes that amount to definitions of "obvious"...)
In this case it may well be true, but that depends on the whole 
collection that has been stored. You can choose to omit some fact but at 
the same time leave in other things that imply part or all of that fact. 
It is hard to be sure that something is not implicit without a process 
equivalent to formal verification. So "If it isn't stored" covers a lot 
more than it appears to.
Bob Wilson