Other Directory Sites: SeekWonder | Directory Owners Forum
The following archive was created by hippie-mail 7.98617-22 on Sat Apr 10 1999 - 01:11:02
bram (bram@gawth.com)
Sun, 30 Aug 1998 23:16:29 -0700 (PDT)
On Thu, 27 Aug 1998, Mike Stay wrote:
> Does anyone know how to exchange identities such that neither
> participant can learn the identity of the other unless both are valid
> and without a trusted third party?
The tricky part is that one of the two parties involved will be the first
to find out what the identity of the other is, and that party can then
simply cut off the communication.
Probably the best you can do is make it so that Alice can send a message
to Bob which can only be read by Bob if he's also actually Charlie, which
can be done by encrypting a message using Charlie's public key and sending
it to Bob (assuming that it's impossible to tell who's public key a
message was encrypted with, which isn't the case using all systems.)
Probably the most difficult (and just plain amusing) cryptographic problem
in encrypted chat is the following: Alice wants to engage in some
perverted and embarassing mating ritual with Bob, but doesn't want to
admit to it unless Bob commits to wanting the same thing. We can assume
that this protocol is done often enough that Alice requesting it be done
doesn't raise suspicion.
That problem is tantamount to Alice and Bob both writing down some number
and then trying to determine if they have the same number written down,
which I believe a very clever and practical protocol was discovered for
just recently, I don't have a reference though.
-Bram
The following archive was created by hippie-mail 7.98617-22 on Sat Apr 10 1999 - 01:11:02