src/HOL/Quickcheck_Benchmark/Needham_Schroeder_Guided_Attacker_Example.thy
changeset 48618 1f7e068b4613
parent 48243 b149de01d669
child 61984 cdea44c775fa
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/Quickcheck_Benchmark/Needham_Schroeder_Guided_Attacker_Example.thy	Thu Jul 26 15:55:19 2012 +0200
@@ -0,0 +1,100 @@
+theory Needham_Schroeder_Guided_Attacker_Example
+imports Needham_Schroeder_Base
+begin
+
+inductive_set ns_public :: "event list set"
+  where
+         (*Initial trace is empty*)
+   Nil:  "[] \<in> ns_public"
+
+ | Fake_NS1:  "\<lbrakk>evs1 \<in> ns_public; Nonce NA \<in> analz (spies evs1) \<rbrakk>
+          \<Longrightarrow> Says Spy B (Crypt (pubEK B) \<lbrace>Nonce NA, Agent A\<rbrace>)
+                # evs1  \<in> ns_public"
+ | Fake_NS2:  "\<lbrakk>evs1 \<in> ns_public; Nonce NA \<in> analz (spies evs1); Nonce NB \<in> analz (spies evs1) \<rbrakk>
+          \<Longrightarrow> Says Spy A (Crypt (pubEK A) \<lbrace>Nonce NA, Nonce NB\<rbrace>)
+                # evs1  \<in> ns_public"
+
+         (*Alice initiates a protocol run, sending a nonce to Bob*)
+ | NS1:  "\<lbrakk>evs1 \<in> ns_public;  Nonce NA \<notin> used evs1\<rbrakk>
+          \<Longrightarrow> Says A B (Crypt (pubEK B) \<lbrace>Nonce NA, Agent A\<rbrace>)
+                # evs1  \<in>  ns_public"
+         (*Bob responds to Alice's message with a further nonce*)
+ | NS2:  "\<lbrakk>evs2 \<in> ns_public;  Nonce NB \<notin> used evs2;
+           Says A' B (Crypt (pubEK B) \<lbrace>Nonce NA, Agent A\<rbrace>) \<in> set evs2\<rbrakk>
+          \<Longrightarrow> Says B A (Crypt (pubEK A) \<lbrace>Nonce NA, Nonce NB\<rbrace>)
+                # evs2  \<in>  ns_public"
+
+         (*Alice proves her existence by sending NB back to Bob.*)
+ | NS3:  "\<lbrakk>evs3 \<in> ns_public;
+           Says A  B (Crypt (pubEK B) \<lbrace>Nonce NA, Agent A\<rbrace>) \<in> set evs3;
+           Says B' A (Crypt (pubEK A) \<lbrace>Nonce NA, Nonce NB\<rbrace>) \<in> set evs3\<rbrakk>
+          \<Longrightarrow> Says A B (Crypt (pubEK B) (Nonce NB)) # evs3 \<in> ns_public"
+
+declare ListMem_iff[symmetric, code_pred_inline]
+
+lemmas [code_pred_intro] = ns_publicp.intros[folded synth'_def]
+
+code_pred [skip_proof] ns_publicp unfolding synth'_def by (rule ns_publicp.cases) fastforce+
+thm ns_publicp.equation
+
+code_pred [generator_cps] ns_publicp .
+thm ns_publicp.generator_cps_equation
+
+
+lemma "ns_publicp evs ==> \<not> (Says Alice Bob (Crypt (pubEK Bob) (Nonce NB))) : set evs"
+quickcheck[smart_exhaustive, depth = 5, timeout = 100, expect = counterexample]
+(*quickcheck[narrowing, size = 6, timeout = 200, verbose, expect = no_counterexample]*)
+oops
+
+lemma
+  "\<lbrakk>ns_publicp evs\<rbrakk>            
+       \<Longrightarrow> Says B A (Crypt (pubEK A) \<lbrace>Nonce NA, Nonce NB\<rbrace>) : set evs
+       \<Longrightarrow> A \<noteq> Spy \<Longrightarrow> B \<noteq> Spy \<Longrightarrow> A \<noteq> B 
+           \<Longrightarrow> Nonce NB \<notin> analz (spies evs)"
+(*quickcheck[smart_exhaustive, depth = 6, timeout = 100, expect = counterexample]
+quickcheck[narrowing, size = 7, timeout = 200, expect = no_counterexample]*)
+oops
+
+section {* Proving the counterexample trace for validation *}
+
+lemma
+  assumes "A = Alice" "B = Bob" "C = Spy" "NA = 0" "NB = 1"
+  assumes "evs = 
+  [Says Alice Spy (Crypt (pubEK Spy) (Nonce 1)),
+   Says Bob Alice (Crypt (pubEK Alice) {|Nonce 0, Nonce 1|}),
+   Says Spy Bob (Crypt (pubEK Bob) {|Nonce 0, Agent Alice|}),
+   Says Alice Spy (Crypt (pubEK Spy) {|Nonce 0, Agent Alice|})]" (is "_ = [?e3, ?e2, ?e1, ?e0]")
+  shows "A \<noteq> Spy" "B \<noteq> Spy" "evs : ns_public" "Nonce NB : analz (knows Spy evs)"
+proof -
+  from assms show "A \<noteq> Spy" by auto
+  from assms show "B \<noteq> Spy" by auto
+  have "[] : ns_public" by (rule Nil)
+  then have first_step: "[?e0] : ns_public"
+  proof (rule NS1)
+    show "Nonce 0 ~: used []" by eval
+  qed
+  then have "[?e1, ?e0] : ns_public"
+  proof (rule Fake_NS1)
+    show "Nonce 0 : analz (knows Spy [?e0])" by eval
+  qed
+  then have "[?e2, ?e1, ?e0] : ns_public"
+  proof (rule NS2)
+    show "Says Spy Bob (Crypt (pubEK Bob) {|Nonce 0, Agent Alice|}) \<in> set [?e1, ?e0]" by simp
+    show " Nonce 1 ~: used [?e1, ?e0]" by eval
+  qed
+  then show "evs : ns_public"
+  unfolding assms
+  proof (rule NS3)
+    show "  Says Alice Spy (Crypt (pubEK Spy) {|Nonce 0, Agent Alice|}) \<in> set [?e2, ?e1, ?e0]" by simp
+    show "Says Bob Alice (Crypt (pubEK Alice) {|Nonce 0, Nonce 1|})
+    : set [?e2, ?e1, ?e0]" by simp
+  qed
+  from assms show "Nonce NB : analz (knows Spy evs)"
+    apply simp
+    apply (rule analz.intros(4))
+    apply (rule analz.intros(1))
+    apply (auto simp add: bad_def)
+    done
+qed
+
+end
\ No newline at end of file