From: IN%"eli+@GS160.SP.CS.CMU.EDU" 10-MAY-1996 17:48:49.87

Each signature has an /a priori/ probability p of correctly indicating validity, but these probilities are not independent at all: this key isn't valid, period. If one certifying signature is incorrect, all others on the same key must be, and vice versa -- about as correlated as they come.

The different paths going through those different signatures will be correlated/non-independent, yes.... but that isn't the problem unless you're considering multiple paths (in a more complicated version).

To limit transitivity, constrain the path length. This limits key reachability too, but I think we agree that it's essential in the real world. (It should also make the math simpler!) The model generalizes to non-binary conceptions of trust, but I don't think these can rehabilitate transitivity. Hmm, there are some possible approaches, though.

IIRC, there have been some sociological studies showing that _everyone_ is linked through 6 or so people. Now, there's the question of whether you _need_ to be linked to _everyone_ - just everyone with whom you want to do business (e.g., excluding authoritarian types doing a sting). It does come back to the elite vs masses distinction; I see nothing wrong (and am in favor of) separation of the elite from the masses. -Allen