author berghofe
Fri, 24 Jul 1998 13:03:20 +0200
changeset 5183 89f162de39cf
parent 3683 aafe719dff14
child 10833 c0844a30ea4e
permissions -rw-r--r--
Adapted to new datatype package.

(*  Title:      HOL/Auth/Shared
    ID:         $Id$
    Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
    Copyright   1996  University of Cambridge

Theory of Shared Keys (common to all symmetric-key protocols)

Shared, long-term keys; initial states of agents

Shared = Event + Finite +

  shrK    :: agent => key  (*symmetric keys*)

  isSym_keys "isSymKey K"	(*All keys are symmetric*)
  inj_shrK   "inj shrK"		(*No two agents have the same long-term key*)

        (*Server knows all long-term keys; other agents know only their own*)
  initState_Server  "initState Server     = Key `` range shrK"
  initState_Friend  "initState (Friend i) = {Key (shrK (Friend i))}"
  initState_Spy     "initState Spy        = Key``shrK``bad"

  (*Unlike the corresponding property of nonces, this cannot be proved.
    We have infinitely many agents and there is nothing to stop their
    long-term keys from exhausting all the natural numbers.  The axiom
    assumes that their keys are dispersed so as to leave room for infinitely
    many fresh session keys.  We could, alternatively, restrict agents to
    an unspecified finite number.*)
  Key_supply_ax  "finite KK ==> EX K. K ~: KK & Key K ~: used evs"