Strength is not right aspect. Global risk is reduced, simply because the aggregate cost of a breach is reduced.
On Thu, 12 Jan 1995, L. Todd Masco wrote:
Isn't it? If an attacker does not know what cipher is used and breaking each is computationally expensive (though not prohibitively so) doesn't that add extra complexity?
The increase in strength, if each cypher was roughly equal, is merely order n, where n is the number of cyphers. If, as is likely, one of the cyphers required a billionfold less power to break than the others, you have decreased strength by an enormous factor. The way to increase strength is to use a cypher, such as IDEA, which has a large key. Key size will increase strength by a factor of billions, not a factor of n. Current key sizes are such that computationally expensive attacks do not work on symmetric cyphers. An attack has to be clever. --------------------------------------------------------------------- We have the right to defend ourselves and our property, because of the kind of animals that we http://nw.com/jamesd/ are. True law derives from this right, not from James A. Donald the arbitrary power of the omnipotent state. jamesd@netcom.com