src/HOL/Auth/Message.ML
author paulson
Tue Aug 20 17:46:24 1996 +0200 (1996-08-20)
changeset 1929 f0839bab4b00
parent 1913 2809adb15eb0
child 1946 b59a3d686436
permissions -rw-r--r--
Working version of NS, messages 1-3, WITH INTERLEAVING
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(*  Title:      HOL/Auth/Message
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    ID:         $Id$
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    Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
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    Copyright   1996  University of Cambridge
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Datatypes of agents and messages;
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Inductive relations "parts", "analz" and "synth"
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*)
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open Message;
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(** Inverse of keys **)
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goal thy "!!K K'. (invKey K = invKey K') = (K=K')";
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by (Step_tac 1);
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br box_equals 1;
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by (REPEAT (rtac invKey 2));
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by (Asm_simp_tac 1);
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qed "invKey_eq";
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Addsimps [invKey, invKey_eq];
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(**** keysFor operator ****)
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goalw thy [keysFor_def] "keysFor {} = {}";
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by (Fast_tac 1);
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qed "keysFor_empty";
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goalw thy [keysFor_def] "keysFor (H Un H') = keysFor H Un keysFor H'";
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by (Fast_tac 1);
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qed "keysFor_Un";
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goalw thy [keysFor_def] "keysFor (UN i. H i) = (UN i. keysFor (H i))";
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by (Fast_tac 1);
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qed "keysFor_UN";
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(*Monotonicity*)
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goalw thy [keysFor_def] "!!G H. G<=H ==> keysFor(G) <= keysFor(H)";
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by (Fast_tac 1);
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qed "keysFor_mono";
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goalw thy [keysFor_def] "keysFor (insert (Agent A) H) = keysFor H";
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by (fast_tac (!claset addss (!simpset)) 1);
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qed "keysFor_insert_Agent";
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goalw thy [keysFor_def] "keysFor (insert (Nonce N) H) = keysFor H";
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by (fast_tac (!claset addss (!simpset)) 1);
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qed "keysFor_insert_Nonce";
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goalw thy [keysFor_def] "keysFor (insert (Key K) H) = keysFor H";
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by (fast_tac (!claset addss (!simpset)) 1);
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qed "keysFor_insert_Key";
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goalw thy [keysFor_def] "keysFor (insert {|X,Y|} H) = keysFor H";
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by (fast_tac (!claset addss (!simpset)) 1);
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qed "keysFor_insert_MPair";
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goalw thy [keysFor_def]
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    "keysFor (insert (Crypt X K) H) = insert (invKey K) (keysFor H)";
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by (Auto_tac());
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by (fast_tac (!claset addIs [image_eqI]) 1);
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qed "keysFor_insert_Crypt";
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Addsimps [keysFor_empty, keysFor_Un, keysFor_UN, 
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	  keysFor_insert_Agent, keysFor_insert_Nonce,
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	  keysFor_insert_Key, keysFor_insert_MPair,
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	  keysFor_insert_Crypt];
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(**** Inductive relation "parts" ****)
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val major::prems = 
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goal thy "[| {|X,Y|} : parts H;       \
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\            [| X : parts H; Y : parts H |] ==> P  \
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\         |] ==> P";
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by (cut_facts_tac [major] 1);
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brs prems 1;
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by (REPEAT (eresolve_tac [asm_rl, parts.Fst, parts.Snd] 1));
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qed "MPair_parts";
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AddIs  [parts.Inj];
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val partsEs = [MPair_parts, make_elim parts.Body];
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AddSEs partsEs;
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(*NB These two rules are UNSAFE in the formal sense, as they discard the
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     compound message.  They work well on THIS FILE, perhaps because its
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     proofs concern only atomic messages.*)
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goal thy "H <= parts(H)";
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by (Fast_tac 1);
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qed "parts_increasing";
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(*Monotonicity*)
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goalw thy parts.defs "!!G H. G<=H ==> parts(G) <= parts(H)";
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by (rtac lfp_mono 1);
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by (REPEAT (ares_tac basic_monos 1));
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qed "parts_mono";
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goal thy "parts{} = {}";
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by (Step_tac 1);
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be parts.induct 1;
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by (ALLGOALS Fast_tac);
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qed "parts_empty";
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Addsimps [parts_empty];
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goal thy "!!X. X: parts{} ==> P";
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by (Asm_full_simp_tac 1);
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qed "parts_emptyE";
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AddSEs [parts_emptyE];
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(*WARNING: loops if H = {Y}, therefore must not be repeated!*)
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goal thy "!!H. X: parts H ==> EX Y:H. X: parts {Y}";
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be parts.induct 1;
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by (ALLGOALS Fast_tac);
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qed "parts_singleton";
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(** Unions **)
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goal thy "parts(G) Un parts(H) <= parts(G Un H)";
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by (REPEAT (ares_tac [Un_least, parts_mono, Un_upper1, Un_upper2] 1));
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val parts_Un_subset1 = result();
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goal thy "parts(G Un H) <= parts(G) Un parts(H)";
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br subsetI 1;
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be parts.induct 1;
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by (ALLGOALS Fast_tac);
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val parts_Un_subset2 = result();
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goal thy "parts(G Un H) = parts(G) Un parts(H)";
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by (REPEAT (ares_tac [equalityI, parts_Un_subset1, parts_Un_subset2] 1));
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qed "parts_Un";
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(*TWO inserts to avoid looping.  This rewrite is better than nothing...*)
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goal thy "parts (insert X (insert Y H)) = parts {X} Un parts {Y} Un parts H";
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by (stac (read_instantiate [("A","H")] insert_is_Un) 1);
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by (stac (read_instantiate [("A","{Y} Un H")] insert_is_Un) 1);
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by (simp_tac (HOL_ss addsimps [parts_Un, Un_assoc]) 1);
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qed "parts_insert2";
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goal thy "(UN x:A. parts(H x)) <= parts(UN x:A. H x)";
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by (REPEAT (ares_tac [UN_least, parts_mono, UN_upper] 1));
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val parts_UN_subset1 = result();
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goal thy "parts(UN x:A. H x) <= (UN x:A. parts(H x))";
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br subsetI 1;
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be parts.induct 1;
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by (ALLGOALS Fast_tac);
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val parts_UN_subset2 = result();
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goal thy "parts(UN x:A. H x) = (UN x:A. parts(H x))";
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by (REPEAT (ares_tac [equalityI, parts_UN_subset1, parts_UN_subset2] 1));
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qed "parts_UN";
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goal thy "parts(UN x. H x) = (UN x. parts(H x))";
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by (simp_tac (!simpset addsimps [UNION1_def, parts_UN]) 1);
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qed "parts_UN1";
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(*Added to simplify arguments to parts, analz and synth*)
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Addsimps [parts_Un, parts_UN, parts_UN1];
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goal thy "insert X (parts H) <= parts(insert X H)";
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by (fast_tac (!claset addEs [impOfSubs parts_mono]) 1);
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qed "parts_insert_subset";
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(** Idempotence and transitivity **)
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goal thy "!!H. X: parts (parts H) ==> X: parts H";
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be parts.induct 1;
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by (ALLGOALS Fast_tac);
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qed "parts_partsE";
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AddSEs [parts_partsE];
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goal thy "parts (parts H) = parts H";
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by (Fast_tac 1);
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qed "parts_idem";
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Addsimps [parts_idem];
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goal thy "!!H. [| X: parts G;  G <= parts H |] ==> X: parts H";
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by (dtac parts_mono 1);
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by (Fast_tac 1);
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qed "parts_trans";
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(*Cut*)
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goal thy "!!H. [| X: parts H;  Y: parts (insert X H) |] ==> Y: parts H";
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be parts_trans 1;
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by (Fast_tac 1);
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qed "parts_cut";
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goal thy "!!H. X: parts H ==> parts (insert X H) = parts H";
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by (fast_tac (!claset addSEs [parts_cut]
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                      addIs [impOfSubs (subset_insertI RS parts_mono)]) 1);
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qed "parts_cut_eq";
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(** Rewrite rules for pulling out atomic messages **)
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goal thy "parts (insert (Agent agt) H) = insert (Agent agt) (parts H)";
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by (rtac (parts_insert_subset RSN (2, equalityI)) 1);
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br subsetI 1;
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be parts.induct 1;
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(*Simplification breaks up equalities between messages;
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  how to make it work for fast_tac??*)
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by (ALLGOALS (fast_tac (!claset addss (!simpset))));
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qed "parts_insert_Agent";
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goal thy "parts (insert (Nonce N) H) = insert (Nonce N) (parts H)";
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by (rtac (parts_insert_subset RSN (2, equalityI)) 1);
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br subsetI 1;
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be parts.induct 1;
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by (ALLGOALS (fast_tac (!claset addss (!simpset))));
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qed "parts_insert_Nonce";
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goal thy "parts (insert (Key K) H) = insert (Key K) (parts H)";
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by (rtac (parts_insert_subset RSN (2, equalityI)) 1);
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br subsetI 1;
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be parts.induct 1;
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by (ALLGOALS (fast_tac (!claset addss (!simpset))));
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qed "parts_insert_Key";
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goal thy "parts (insert (Crypt X K) H) = \
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\         insert (Crypt X K) (parts (insert X H))";
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br equalityI 1;
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br subsetI 1;
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be parts.induct 1;
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by (Auto_tac());
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be parts.induct 1;
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by (ALLGOALS (best_tac (!claset addIs [parts.Body])));
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qed "parts_insert_Crypt";
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goal thy "parts (insert {|X,Y|} H) = \
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\         insert {|X,Y|} (parts (insert X (insert Y H)))";
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br equalityI 1;
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br subsetI 1;
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be parts.induct 1;
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by (Auto_tac());
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be parts.induct 1;
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by (ALLGOALS (best_tac (!claset addIs [parts.Fst, parts.Snd])));
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qed "parts_insert_MPair";
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Addsimps [parts_insert_Agent, parts_insert_Nonce, 
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	  parts_insert_Key, parts_insert_Crypt, parts_insert_MPair];
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(**** Inductive relation "analz" ****)
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val major::prems = 
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goal thy "[| {|X,Y|} : analz H;       \
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\            [| X : analz H; Y : analz H |] ==> P  \
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\         |] ==> P";
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by (cut_facts_tac [major] 1);
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brs prems 1;
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by (REPEAT (eresolve_tac [asm_rl, analz.Fst, analz.Snd] 1));
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qed "MPair_analz";
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AddIs  [analz.Inj];
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AddSEs [MPair_analz];
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AddDs  [analz.Decrypt];
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Addsimps [analz.Inj];
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goal thy "H <= analz(H)";
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by (Fast_tac 1);
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qed "analz_increasing";
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goal thy "analz H <= parts H";
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by (rtac subsetI 1);
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be analz.induct 1;
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by (ALLGOALS Fast_tac);
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qed "analz_subset_parts";
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bind_thm ("not_parts_not_analz", analz_subset_parts RS contra_subsetD);
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goal thy "parts (analz H) = parts H";
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br equalityI 1;
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br (analz_subset_parts RS parts_mono RS subset_trans) 1;
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by (Simp_tac 1);
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by (fast_tac (!claset addDs [analz_increasing RS parts_mono RS subsetD]) 1);
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qed "parts_analz";
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Addsimps [parts_analz];
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goal thy "analz (parts H) = parts H";
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by (Auto_tac());
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be analz.induct 1;
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by (Auto_tac());
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qed "analz_parts";
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Addsimps [analz_parts];
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(*Monotonicity; Lemma 1 of Lowe*)
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goalw thy analz.defs "!!G H. G<=H ==> analz(G) <= analz(H)";
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by (rtac lfp_mono 1);
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by (REPEAT (ares_tac basic_monos 1));
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qed "analz_mono";
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(** General equational properties **)
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goal thy "analz{} = {}";
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by (Step_tac 1);
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be analz.induct 1;
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by (ALLGOALS Fast_tac);
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qed "analz_empty";
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Addsimps [analz_empty];
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(*Converse fails: we can analz more from the union than from the 
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  separate parts, as a key in one might decrypt a message in the other*)
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goal thy "analz(G) Un analz(H) <= analz(G Un H)";
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by (REPEAT (ares_tac [Un_least, analz_mono, Un_upper1, Un_upper2] 1));
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qed "analz_Un";
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goal thy "insert X (analz H) <= analz(insert X H)";
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by (fast_tac (!claset addEs [impOfSubs analz_mono]) 1);
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qed "analz_insert";
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(** Rewrite rules for pulling out atomic messages **)
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goal thy "analz (insert (Agent agt) H) = insert (Agent agt) (analz H)";
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by (rtac (analz_insert RSN (2, equalityI)) 1);
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br subsetI 1;
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be analz.induct 1;
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(*Simplification breaks up equalities between messages;
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  how to make it work for fast_tac??*)
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by (ALLGOALS (fast_tac (!claset addss (!simpset))));
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qed "analz_insert_Agent";
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goal thy "analz (insert (Nonce N) H) = insert (Nonce N) (analz H)";
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by (rtac (analz_insert RSN (2, equalityI)) 1);
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br subsetI 1;
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be analz.induct 1;
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by (ALLGOALS (fast_tac (!claset addss (!simpset))));
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qed "analz_insert_Nonce";
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(*Can only pull out Keys if they are not needed to decrypt the rest*)
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goalw thy [keysFor_def]
paulson@1913
   338
    "!!K. K ~: keysFor (analz H) ==>  \
paulson@1913
   339
\         analz (insert (Key K) H) = insert (Key K) (analz H)";
paulson@1913
   340
by (rtac (analz_insert RSN (2, equalityI)) 1);
paulson@1839
   341
br subsetI 1;
paulson@1913
   342
be analz.induct 1;
paulson@1839
   343
by (ALLGOALS (fast_tac (!claset addss (!simpset))));
paulson@1913
   344
qed "analz_insert_Key";
paulson@1839
   345
paulson@1913
   346
goal thy "analz (insert {|X,Y|} H) = \
paulson@1913
   347
\         insert {|X,Y|} (analz (insert X (insert Y H)))";
paulson@1885
   348
br equalityI 1;
paulson@1885
   349
br subsetI 1;
paulson@1913
   350
be analz.induct 1;
paulson@1885
   351
by (Auto_tac());
paulson@1913
   352
be analz.induct 1;
paulson@1913
   353
by (ALLGOALS (deepen_tac (!claset addIs [analz.Fst, analz.Snd, analz.Decrypt]) 0));
paulson@1913
   354
qed "analz_insert_MPair";
paulson@1885
   355
paulson@1885
   356
(*Can pull out enCrypted message if the Key is not known*)
paulson@1913
   357
goal thy "!!H. Key (invKey K) ~: analz H ==>  \
paulson@1913
   358
\              analz (insert (Crypt X K) H) = \
paulson@1913
   359
\              insert (Crypt X K) (analz H)";
paulson@1913
   360
by (rtac (analz_insert RSN (2, equalityI)) 1);
paulson@1839
   361
br subsetI 1;
paulson@1913
   362
be analz.induct 1;
paulson@1839
   363
by (ALLGOALS (fast_tac (!claset addss (!simpset))));
paulson@1913
   364
qed "analz_insert_Crypt";
paulson@1839
   365
paulson@1913
   366
goal thy "!!H. Key (invKey K) : analz H ==>  \
paulson@1913
   367
\              analz (insert (Crypt X K) H) <= \
paulson@1913
   368
\              insert (Crypt X K) (analz (insert X H))";
paulson@1839
   369
br subsetI 1;
paulson@1913
   370
by (eres_inst_tac [("za","x")] analz.induct 1);
paulson@1839
   371
by (ALLGOALS (fast_tac (!claset addss (!simpset))));
paulson@1839
   372
val lemma1 = result();
paulson@1839
   373
paulson@1913
   374
goal thy "!!H. Key (invKey K) : analz H ==>  \
paulson@1913
   375
\              insert (Crypt X K) (analz (insert X H)) <= \
paulson@1913
   376
\              analz (insert (Crypt X K) H)";
paulson@1839
   377
by (Auto_tac());
paulson@1913
   378
by (eres_inst_tac [("za","x")] analz.induct 1);
paulson@1839
   379
by (Auto_tac());
paulson@1913
   380
by (best_tac (!claset addIs [subset_insertI RS analz_mono RS subsetD,
paulson@1913
   381
			     analz.Decrypt]) 1);
paulson@1839
   382
val lemma2 = result();
paulson@1839
   383
paulson@1913
   384
goal thy "!!H. Key (invKey K) : analz H ==>  \
paulson@1913
   385
\              analz (insert (Crypt X K) H) = \
paulson@1913
   386
\              insert (Crypt X K) (analz (insert X H))";
paulson@1839
   387
by (REPEAT (ares_tac [equalityI, lemma1, lemma2] 1));
paulson@1913
   388
qed "analz_insert_Decrypt";
paulson@1839
   389
paulson@1885
   390
(*Case analysis: either the message is secure, or it is not!
paulson@1885
   391
  Use with expand_if;  apparently split_tac does not cope with patterns
paulson@1913
   392
  such as "analz (insert (Crypt X' K) H)" *)
paulson@1913
   393
goal thy "analz (insert (Crypt X' K) H) = \
paulson@1913
   394
\         (if (Key (invKey K)  : analz H) then    \
paulson@1913
   395
\               insert (Crypt X' K) (analz (insert X' H)) \
paulson@1913
   396
\          else insert (Crypt X' K) (analz H))";
paulson@1913
   397
by (excluded_middle_tac "Key (invKey K)  : analz H " 1);
paulson@1913
   398
by (ALLGOALS (asm_simp_tac (!simpset addsimps [analz_insert_Crypt, 
paulson@1913
   399
					       analz_insert_Decrypt])));
paulson@1913
   400
qed "analz_Crypt_if";
paulson@1885
   401
paulson@1913
   402
Addsimps [analz_insert_Agent, analz_insert_Nonce, 
paulson@1913
   403
	  analz_insert_Key, analz_insert_MPair, 
paulson@1913
   404
	  analz_Crypt_if];
paulson@1839
   405
paulson@1839
   406
(*This rule supposes "for the sake of argument" that we have the key.*)
paulson@1913
   407
goal thy  "analz (insert (Crypt X K) H) <=  \
paulson@1913
   408
\          insert (Crypt X K) (analz (insert X H))";
paulson@1839
   409
br subsetI 1;
paulson@1913
   410
be analz.induct 1;
paulson@1839
   411
by (Auto_tac());
paulson@1913
   412
qed "analz_insert_Crypt_subset";
paulson@1839
   413
paulson@1839
   414
paulson@1839
   415
(** Idempotence and transitivity **)
paulson@1839
   416
paulson@1913
   417
goal thy "!!H. X: analz (analz H) ==> X: analz H";
paulson@1913
   418
be analz.induct 1;
paulson@1839
   419
by (ALLGOALS Fast_tac);
paulson@1913
   420
qed "analz_analzE";
paulson@1913
   421
AddSEs [analz_analzE];
paulson@1839
   422
paulson@1913
   423
goal thy "analz (analz H) = analz H";
paulson@1839
   424
by (Fast_tac 1);
paulson@1913
   425
qed "analz_idem";
paulson@1913
   426
Addsimps [analz_idem];
paulson@1839
   427
paulson@1913
   428
goal thy "!!H. [| X: analz G;  G <= analz H |] ==> X: analz H";
paulson@1913
   429
by (dtac analz_mono 1);
paulson@1839
   430
by (Fast_tac 1);
paulson@1913
   431
qed "analz_trans";
paulson@1839
   432
paulson@1839
   433
(*Cut; Lemma 2 of Lowe*)
paulson@1913
   434
goal thy "!!H. [| X: analz H;  Y: analz (insert X H) |] ==> Y: analz H";
paulson@1913
   435
be analz_trans 1;
paulson@1839
   436
by (Fast_tac 1);
paulson@1913
   437
qed "analz_cut";
paulson@1839
   438
paulson@1839
   439
(*Cut can be proved easily by induction on
paulson@1913
   440
   "!!H. Y: analz (insert X H) ==> X: analz H --> Y: analz H"
paulson@1839
   441
*)
paulson@1839
   442
paulson@1885
   443
paulson@1913
   444
(** A congruence rule for "analz" **)
paulson@1885
   445
paulson@1913
   446
goal thy "!!H. [| analz G <= analz G'; analz H <= analz H' \
paulson@1913
   447
\              |] ==> analz (G Un H) <= analz (G' Un H')";
paulson@1885
   448
by (Step_tac 1);
paulson@1913
   449
be analz.induct 1;
paulson@1913
   450
by (ALLGOALS (best_tac (!claset addIs [analz_mono RS subsetD])));
paulson@1913
   451
qed "analz_subset_cong";
paulson@1885
   452
paulson@1913
   453
goal thy "!!H. [| analz G = analz G'; analz H = analz H' \
paulson@1913
   454
\              |] ==> analz (G Un H) = analz (G' Un H')";
paulson@1913
   455
by (REPEAT_FIRST (ares_tac [equalityI, analz_subset_cong]
paulson@1885
   456
	  ORELSE' etac equalityE));
paulson@1913
   457
qed "analz_cong";
paulson@1885
   458
paulson@1885
   459
paulson@1913
   460
goal thy "!!H. analz H = analz H' ==> analz(insert X H) = analz(insert X H')";
paulson@1885
   461
by (asm_simp_tac (!simpset addsimps [insert_def] 
paulson@1913
   462
		           setloop (rtac analz_cong)) 1);
paulson@1913
   463
qed "analz_insert_cong";
paulson@1885
   464
paulson@1913
   465
(*If there are no pairs or encryptions then analz does nothing*)
paulson@1839
   466
goal thy "!!H. [| ALL X Y. {|X,Y|} ~: H;  ALL X K. Crypt X K ~: H |] ==> \
paulson@1913
   467
\         analz H = H";
paulson@1839
   468
by (Step_tac 1);
paulson@1913
   469
be analz.induct 1;
paulson@1839
   470
by (ALLGOALS Fast_tac);
paulson@1913
   471
qed "analz_trivial";
paulson@1839
   472
paulson@1839
   473
(*Helps to prove Fake cases*)
paulson@1913
   474
goal thy "!!X. X: analz (UN i. analz (H i)) ==> X: analz (UN i. H i)";
paulson@1913
   475
be analz.induct 1;
paulson@1913
   476
by (ALLGOALS (fast_tac (!claset addEs [impOfSubs analz_mono])));
paulson@1839
   477
val lemma = result();
paulson@1839
   478
paulson@1913
   479
goal thy "analz (UN i. analz (H i)) = analz (UN i. H i)";
paulson@1839
   480
by (fast_tac (!claset addIs [lemma]
paulson@1913
   481
		      addEs [impOfSubs analz_mono]) 1);
paulson@1913
   482
qed "analz_UN_analz";
paulson@1913
   483
Addsimps [analz_UN_analz];
paulson@1839
   484
paulson@1839
   485
paulson@1913
   486
(**** Inductive relation "synth" ****)
paulson@1839
   487
paulson@1913
   488
AddIs  synth.intrs;
paulson@1839
   489
paulson@1913
   490
goal thy "H <= synth(H)";
paulson@1839
   491
by (Fast_tac 1);
paulson@1913
   492
qed "synth_increasing";
paulson@1839
   493
paulson@1839
   494
(*Monotonicity*)
paulson@1913
   495
goalw thy synth.defs "!!G H. G<=H ==> synth(G) <= synth(H)";
paulson@1839
   496
by (rtac lfp_mono 1);
paulson@1839
   497
by (REPEAT (ares_tac basic_monos 1));
paulson@1913
   498
qed "synth_mono";
paulson@1839
   499
paulson@1839
   500
(** Unions **)
paulson@1839
   501
paulson@1913
   502
(*Converse fails: we can synth more from the union than from the 
paulson@1839
   503
  separate parts, building a compound message using elements of each.*)
paulson@1913
   504
goal thy "synth(G) Un synth(H) <= synth(G Un H)";
paulson@1913
   505
by (REPEAT (ares_tac [Un_least, synth_mono, Un_upper1, Un_upper2] 1));
paulson@1913
   506
qed "synth_Un";
paulson@1839
   507
paulson@1913
   508
goal thy "insert X (synth H) <= synth(insert X H)";
paulson@1913
   509
by (fast_tac (!claset addEs [impOfSubs synth_mono]) 1);
paulson@1913
   510
qed "synth_insert";
paulson@1885
   511
paulson@1839
   512
(** Idempotence and transitivity **)
paulson@1839
   513
paulson@1913
   514
goal thy "!!H. X: synth (synth H) ==> X: synth H";
paulson@1913
   515
be synth.induct 1;
paulson@1839
   516
by (ALLGOALS Fast_tac);
paulson@1913
   517
qed "synth_synthE";
paulson@1913
   518
AddSEs [synth_synthE];
paulson@1839
   519
paulson@1913
   520
goal thy "synth (synth H) = synth H";
paulson@1839
   521
by (Fast_tac 1);
paulson@1913
   522
qed "synth_idem";
paulson@1839
   523
paulson@1913
   524
goal thy "!!H. [| X: synth G;  G <= synth H |] ==> X: synth H";
paulson@1913
   525
by (dtac synth_mono 1);
paulson@1839
   526
by (Fast_tac 1);
paulson@1913
   527
qed "synth_trans";
paulson@1839
   528
paulson@1839
   529
(*Cut; Lemma 2 of Lowe*)
paulson@1913
   530
goal thy "!!H. [| X: synth H;  Y: synth (insert X H) |] ==> Y: synth H";
paulson@1913
   531
be synth_trans 1;
paulson@1839
   532
by (Fast_tac 1);
paulson@1913
   533
qed "synth_cut";
paulson@1839
   534
paulson@1839
   535
paulson@1839
   536
(*Can only produce a nonce or key if it is already known,
paulson@1913
   537
  but can synth a pair or encryption from its components...*)
paulson@1913
   538
val mk_cases = synth.mk_cases msg.simps;
paulson@1839
   539
paulson@1913
   540
(*NO Agent_synth, as any Agent name can be synthd*)
paulson@1913
   541
val Nonce_synth = mk_cases "Nonce n : synth H";
paulson@1913
   542
val Key_synth   = mk_cases "Key K : synth H";
paulson@1913
   543
val MPair_synth = mk_cases "{|X,Y|} : synth H";
paulson@1913
   544
val Crypt_synth = mk_cases "Crypt X K : synth H";
paulson@1839
   545
paulson@1913
   546
AddSEs [Nonce_synth, Key_synth, MPair_synth, Crypt_synth];
paulson@1839
   547
paulson@1913
   548
goal thy "(Nonce N : synth H) = (Nonce N : H)";
paulson@1839
   549
by (Fast_tac 1);
paulson@1913
   550
qed "Nonce_synth_eq";
paulson@1839
   551
paulson@1913
   552
goal thy "(Key K : synth H) = (Key K : H)";
paulson@1839
   553
by (Fast_tac 1);
paulson@1913
   554
qed "Key_synth_eq";
paulson@1839
   555
paulson@1913
   556
Addsimps [Nonce_synth_eq, Key_synth_eq];
paulson@1839
   557
paulson@1839
   558
paulson@1839
   559
goalw thy [keysFor_def]
paulson@1913
   560
    "keysFor (synth H) = keysFor H Un invKey``{K. Key K : H}";
paulson@1839
   561
by (Fast_tac 1);
paulson@1913
   562
qed "keysFor_synth";
paulson@1913
   563
Addsimps [keysFor_synth];
paulson@1839
   564
paulson@1839
   565
paulson@1913
   566
(*** Combinations of parts, analz and synth ***)
paulson@1839
   567
paulson@1913
   568
goal thy "parts (synth H) = parts H Un synth H";
paulson@1839
   569
br equalityI 1;
paulson@1839
   570
br subsetI 1;
paulson@1839
   571
be parts.induct 1;
paulson@1839
   572
by (ALLGOALS
paulson@1913
   573
    (best_tac (!claset addIs ((synth_increasing RS parts_mono RS subsetD)
paulson@1839
   574
			     ::parts.intrs))));
paulson@1913
   575
qed "parts_synth";
paulson@1913
   576
Addsimps [parts_synth];
paulson@1839
   577
paulson@1913
   578
goal thy "analz (synth H) = analz H Un synth H";
paulson@1839
   579
br equalityI 1;
paulson@1839
   580
br subsetI 1;
paulson@1913
   581
be analz.induct 1;
paulson@1839
   582
by (best_tac
paulson@1913
   583
    (!claset addIs [synth_increasing RS analz_mono RS subsetD]) 5);
paulson@1839
   584
(*Strange that best_tac just can't hack this one...*)
paulson@1913
   585
by (ALLGOALS (deepen_tac (!claset addIs analz.intrs) 0));
paulson@1913
   586
qed "analz_synth";
paulson@1913
   587
Addsimps [analz_synth];
paulson@1839
   588
paulson@1839
   589
(*Hard to prove; still needed now that there's only one Enemy?*)
paulson@1913
   590
goal thy "analz (UN i. synth (H i)) = \
paulson@1913
   591
\         analz (UN i. H i) Un (UN i. synth (H i))";
paulson@1839
   592
br equalityI 1;
paulson@1839
   593
br subsetI 1;
paulson@1913
   594
be analz.induct 1;
paulson@1839
   595
by (best_tac
paulson@1913
   596
    (!claset addEs [impOfSubs synth_increasing,
paulson@1913
   597
		    impOfSubs analz_mono]) 5);
paulson@1839
   598
by (Best_tac 1);
paulson@1913
   599
by (deepen_tac (!claset addIs [analz.Fst]) 0 1);
paulson@1913
   600
by (deepen_tac (!claset addIs [analz.Snd]) 0 1);
paulson@1913
   601
by (deepen_tac (!claset addSEs [analz.Decrypt]
paulson@1913
   602
			addIs  [analz.Decrypt]) 0 1);
paulson@1913
   603
qed "analz_UN1_synth";
paulson@1913
   604
Addsimps [analz_UN1_synth];
paulson@1929
   605
paulson@1929
   606
(*Especially for reasoning about the Fake rule in traces*)
paulson@1929
   607
goal thy "!!Y. X: G ==> parts(insert X H) <= parts G Un parts H";
paulson@1929
   608
br ([parts_mono, parts_Un_subset2] MRS subset_trans) 1;
paulson@1929
   609
by (Fast_tac 1);
paulson@1929
   610
qed "parts_insert_subset_Un";
paulson@1929
   611
paulson@1929
   612
(*Also for the Fake rule, but more specific*)
paulson@1929
   613
goal thy "!!H. X: synth (analz H) ==> \
paulson@1929
   614
\              parts (insert X H) <= synth (analz H) Un parts H";
paulson@1929
   615
bd parts_insert_subset_Un 1;
paulson@1929
   616
by (Full_simp_tac 1);
paulson@1929
   617
by (Fast_tac 1);
paulson@1929
   618
qed "synth_analz_parts_insert_subset_Un";
paulson@1929
   619
paulson@1929
   620
paulson@1929
   621
paulson@1929
   622
(*We do NOT want Crypt... messages broken up in protocols!!*)
paulson@1929
   623
Delrules partsEs;
paulson@1929
   624