Notes on  ALICE AND BOB 

The archetypal individuals used as examples in discussions of
cryptographic protocols. Originally, theorists would say something
like: "A communicates with someone who claims to be B, So to be sure,
A tests that B knows a secret number K. So A sends to B a random
number X. B then forms Y by encrypting X under key K and sends Y back
to A" Because this sort of thing is quite hard to follow, theorists
stopped using the unadorned letters A and B to represent the main
players and started calling them Alice and Bob. So now we say "Alice
communicates with someone claiming to be Bob, and to be sure, Alice
tests that Bob knows a secret number K. Alice sends to Bob a random
number X. Bob then forms Y by encrypting X under key K and sends Y
back to Alice". A whole mythology rapidly grew up around the
metasyntactic names; see http://www.conceptlabs.co.uk/alicebob.html.

In Bruce Schneier's definitive introductory text Applied Cryptography
(2nd ed., 1996, John Wiley & Sons, ISBN 0-471-11709-9) he introduced
a table of dramatis personae headed by Alice and Bob. Others include
Carol (a participant in three- and four-party protocols), Dave (a
participant in four-party protocols), Eve (an eavesdropper), Mallory
(a malicious active attacker), Trent (a trusted arbitrator), Walter
(a warden), Peggy (a prover) and Victor (a verifier). These names for
roles are either already standard or, given the wide popularity of
the book, may be expected to quickly become so.

J3N Research Labs

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