Here's an idea. Let's say some program is a stream of bytes. Every 64th byte is not an "instruction," it is a "security code." Specifically, the codes are such that the whole ball of wax -- program+security -- gets public-key-encoded to something nice, like it has a bunch of 0s. Your computer has built in hardware for public key crypto. It terminates execution if program fails to satisfy security demands. Point is, it is not possible for anybody to produce malware with valid security codebytes, unless they already know your computer's secret key. E.g they either had your cooperation, or they already had access to your computer's code. -- Warren D. Smith http://RangeVoting.org <-- add your endorsement (by clicking "endorse" as 1st step)