Clouds!

[Ian Batten]

> 
> [1] Here would I add a reference to a paper about using mathematical
> transforms to perform computing on encrypted data without decrypting
> it, but I'm afraid I can't find it right this minute ...

Homomorphic encryption.   Fascinating, but not practical today, nor likely to become so any time soon.  And the definition of "computation" it uses is not hugely useful for the purposes this list is concerned with.

ian