src/HOL/Auth/Shared.thy

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/Auth/Shared.thy	Wed Aug 21 13:25:27 1996 +0200
@@ -0,0 +1,67 @@
+(*  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)
+
+Server keys; initial states of agents; new nonces and keys; function "sees" 
+*)
+
+Shared = Message + List + 
+
+consts
+  serverKey    :: agent => key  (*symmetric keys*)
+
+rules
+  isSym_serverKey "isSymKey (serverKey A)"
+
+consts  (*Initial states of agents -- parameter of the construction*)
+  initState :: agent => msg set
+
+primrec initState agent
+        (*Server knows all keys; other agents know only their own*)
+  initState_Server  "initState Server     = Key `` range serverKey"
+  initState_Friend  "initState (Friend i) = {Key (serverKey (Friend i))}"
+  initState_Enemy   "initState Enemy  = {Key (serverKey Enemy)}"
+
+datatype  (*Messages, and components of agent stores*)
+  event = Says agent agent msg
+        | Notes agent msg
+
+consts  
+  sees1 :: [agent, event] => msg set
+
+primrec sees1 event
+           (*First agent recalls all that it says, but NOT everything
+             that is sent to it; it must note such things if/when received*)
+  sees1_Says  "sees1 A (Says A' B X)  = (if A:{A',Enemy} then {X} else {})"
+          (*part of A's internal state*)
+  sees1_Notes "sees1 A (Notes A' X)   = (if A=A' then {X} else {})"
+
+consts  
+  sees :: [agent, event list] => msg set
+
+primrec sees list
+        (*Initial knowledge includes all public keys and own private key*)
+  sees_Nil  "sees A []       = initState A"
+  sees_Cons "sees A (ev#evs) = sees1 A ev Un sees A evs"
+
+
+(*Agents generate "random" nonces.  Different traces always yield
+  different nonces.  Same applies for keys.*)
+consts
+  newN :: "event list => nat"
+  newK :: "event list => key"
+
+rules
+  inj_serverKey "inj serverKey"
+
+  inj_newN   "inj newN"
+  fresh_newN "Nonce (newN evs) ~: parts (initState B)" 
+
+  inj_newK   "inj newK"
+  fresh_newK "Key (newK evs) ~: parts (initState B)" 
+  isSym_newK "isSymKey (newK evs)"
+
+end