NODE db1524eaRe: More elveator problem
wlkngowl@unix.asb.com (Mutatis Mutantdis)Sun, 10 Dec 95 22:18:25 PST
On Sat, 9 Dec 1995 00:23:41 -0800, Jerry Whiting wrote:
>More on The Elevator Problem:
>I'll confess that we're working on a new private key encryption product. Free
>and clear of existing claims on intellectual property, I'd like a protocol
>that answers the elevator problem: how can Alice and Bob agree on a private
>key via a compromised channel? I don't want them to meet under a street lamp
>and whisper in each other's ears _before_ trying to establish a secret on a
>crowded elevator.
[..]
>Something that I neglected to mention before is that Alice and Bob do have a
>unique ID within this system, not that they necessarily know each others. If
>one assumes that they do, they then share a secret: the knowledge of each
>other's unique ID.
[..]
Wait... are unique IDs secret from others? Can they share theirs with
ea. other without compromising something?
Maybe using a hash of their combined secret ideas (adding them, or
mixing the bits... how long is the unique ID?) can be used to generate
a "key" to exchange other information....
>Jerry Whiting
>jwhiting@azalea.com
NODE e9cc3601Re: More elveator problem
futplex@pseudonym.com (Futplex)Tue, 12 Dec 1995 11:35:27 +0800
The cypherpunk formerly known as Deranged Mutant writes:
> Wait... are unique IDs secret from others? Can they share theirs with
> ea. other without compromising something?
>
> Maybe using a hash of their combined secret ideas (adding them, or
> mixing the bits... how long is the unique ID?) can be used to generate
> a "key" to exchange other information....
The fundamental problem is that Eve and her sisters get to hear both IDs
when Alice and Bob exchange them. So Eve can also do the hash, XOR, or
whatever. DH skirts this obstacle brilliantly.
-Futplex <futplex@pseudonym.com>