[cap-talk] the prize - scope and mechanisms

[David Hopwood]

Jed Donnelley wrote:
> If the issue is protecting data traveling across a communication
> channel from eves dropping (unauthorized reading) then one
> approach is to keep the channel physically protected (e.g. within
> a single computer keeping it unavailable for unauthorized reading
> or in the context of a network keeping the physical channel
> protected - e.g. by electrical shielding, etc.).  Another approach
> is to use cryptographic means to protect the data while on the
> channel.  The risk then of unauthorized reading is not truly
> zero (we all know of many examples of broken cryptographic
> systems), but it can, in my opinion, be made "as small as need
> be" by using a cryptographic system that is strong enough for
> the practical needs.

In practice, cryptographic systems tend to break due to protocol
failures, not due to an algorithm weaknesses or brute-force attacks.
If a protocol failure is possible and an attacker both knows how to
and has a motive to induce it, the risk is *high*; otherwise the
risk is essentially zero. Flaws in cryptographic systems are quite
similar to other software-based security flaws in this respect.

-- 
David Hopwood <david.nospam.hopwood at blueyonder.co.uk>