@Brian: Perhaps it is a matter of trusting your supply chain.
If I were designing something that needed to be mega-safe (planes, submarines, space probes, industrial control systems ... I wouldn't even trust myself (but then, I know the sort of things I get up to :-)
In some respects, is this no different than a software programmer putting in "Easter Eggs". I know the implications could be a lot higher, but I think this has always been happening. Perhaps it is a matter of trusting your supply chain.
Hi Brian -- one problem with outsourcing is not knowing 100% what comes back in. Sometimes all the prime company does is verify the functionality of a complex function that was developed by a third party -- they don't examine the HDL or firmware code line-by-line -- so who knows what "back doors" have been added while no one was looking?