author | paulson |
Tue, 08 Sep 1998 15:17:11 +0200 | |
changeset 5434 | 9b4bed3f394c |
parent 5421 | 01fc8d6a40f2 |
child 5492 | d9fc3457554e |
permissions | -rw-r--r-- |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
1 |
(* Title: HOL/Auth/Yahalom2 |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
2 |
ID: $Id$ |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
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|
3 |
Author: Lawrence C Paulson, Cambridge University Computer Laboratory |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
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|
4 |
Copyright 1996 University of Cambridge |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
5 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
6 |
Inductive relation "yahalom" for the Yahalom protocol, Variant 2. |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
7 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
8 |
This version trades encryption of NB for additional explicitness in YM3. |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
9 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
10 |
From page 259 of |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
11 |
Burrows, Abadi and Needham. A Logic of Authentication. |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
12 |
Proc. Royal Soc. 426 (1989) |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
13 |
*) |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
14 |
|
5066
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
4831
diff
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|
15 |
AddEs spies_partsEs; |
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
4831
diff
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|
16 |
AddDs [impOfSubs analz_subset_parts]; |
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
4831
diff
changeset
|
17 |
AddDs [impOfSubs Fake_parts_insert]; |
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
4831
diff
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|
18 |
|
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
4831
diff
changeset
|
19 |
|
2323 | 20 |
(*A "possibility property": there are traces that reach the end*) |
5434
9b4bed3f394c
Got rid of not_Says_to_self and most uses of ~= in definitions and theorems
paulson
parents:
5421
diff
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|
21 |
Goal "EX X NB K. EX evs: yahalom. \ |
5114
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
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diff
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|
22 |
\ Says A B {|X, Crypt K (Nonce NB)|} : set evs"; |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
23 |
by (REPEAT (resolve_tac [exI,bexI] 1)); |
2516
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Now with Andy Gordon's treatment of freshness to replace newN/K
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parents:
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|
24 |
by (rtac (yahalom.Nil RS yahalom.YM1 RS yahalom.YM2 RS yahalom.YM3 RS |
4d68fbe6378b
Now with Andy Gordon's treatment of freshness to replace newN/K
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parents:
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|
25 |
yahalom.YM4) 2); |
4d68fbe6378b
Now with Andy Gordon's treatment of freshness to replace newN/K
paulson
parents:
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diff
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|
26 |
by possibility_tac; |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
27 |
result(); |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
28 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
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|
29 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
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|
30 |
(**** Inductive proofs about yahalom ****) |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
31 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
32 |
(** For reasoning about the encrypted portion of messages **) |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
33 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
34 |
(*Lets us treat YM4 using a similar argument as for the Fake case.*) |
5114
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
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|
35 |
Goal "Says S A {|NB, Crypt (shrK A) Y, X|} : set evs ==> \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
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|
36 |
\ X : analz (spies evs)"; |
4091 | 37 |
by (blast_tac (claset() addSDs [Says_imp_spies RS analz.Inj]) 1); |
3683 | 38 |
qed "YM4_analz_spies"; |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
39 |
|
3683 | 40 |
bind_thm ("YM4_parts_spies", |
41 |
YM4_analz_spies RS (impOfSubs analz_subset_parts)); |
|
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
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|
42 |
|
2155 | 43 |
(*Relates to both YM4 and Oops*) |
5114
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Deleted leading parameters thanks to new Goal command
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parents:
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|
44 |
Goal "Says S A {|NB, Crypt (shrK A) {|B,K,NA|}, X|} : set evs ==> \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
45 |
\ K : parts (spies evs)"; |
5066
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
4831
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|
46 |
by (Blast_tac 1); |
3683 | 47 |
qed "YM4_Key_parts_spies"; |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
48 |
|
3683 | 49 |
(*For proving the easier theorems about X ~: parts (spies evs).*) |
50 |
fun parts_spies_tac i = |
|
51 |
forward_tac [YM4_Key_parts_spies] (i+6) THEN |
|
52 |
forward_tac [YM4_parts_spies] (i+5) THEN |
|
3519
ab0a9fbed4c0
Changing "lost" from a parameter of protocol definitions to a constant.
paulson
parents:
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diff
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|
53 |
prove_simple_subgoals_tac i; |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
54 |
|
3519
ab0a9fbed4c0
Changing "lost" from a parameter of protocol definitions to a constant.
paulson
parents:
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diff
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|
55 |
(*Induction for regularity theorems. If induction formula has the form |
3683 | 56 |
X ~: analz (spies evs) --> ... then it shortens the proof by discarding |
57 |
needless information about analz (insert X (spies evs)) *) |
|
3519
ab0a9fbed4c0
Changing "lost" from a parameter of protocol definitions to a constant.
paulson
parents:
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|
58 |
fun parts_induct_tac i = |
ab0a9fbed4c0
Changing "lost" from a parameter of protocol definitions to a constant.
paulson
parents:
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|
59 |
etac yahalom.induct i |
ab0a9fbed4c0
Changing "lost" from a parameter of protocol definitions to a constant.
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parents:
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diff
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|
60 |
THEN |
ab0a9fbed4c0
Changing "lost" from a parameter of protocol definitions to a constant.
paulson
parents:
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|
61 |
REPEAT (FIRSTGOAL analz_mono_contra_tac) |
3683 | 62 |
THEN parts_spies_tac i; |
3432 | 63 |
|
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
64 |
|
3683 | 65 |
(** Theorems of the form X ~: parts (spies evs) imply that NOBODY |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
66 |
sends messages containing X! **) |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
67 |
|
3683 | 68 |
(*Spy never sees another agent's shared key! (unless it's bad at start)*) |
5114
c729d4c299c1
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paulson
parents:
5076
diff
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|
69 |
Goal "evs : yahalom ==> (Key (shrK A) : parts (spies evs)) = (A : bad)"; |
3519
ab0a9fbed4c0
Changing "lost" from a parameter of protocol definitions to a constant.
paulson
parents:
3516
diff
changeset
|
70 |
by (parts_induct_tac 1); |
5066
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
4831
diff
changeset
|
71 |
by (ALLGOALS Blast_tac); |
2516
4d68fbe6378b
Now with Andy Gordon's treatment of freshness to replace newN/K
paulson
parents:
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diff
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|
72 |
qed "Spy_see_shrK"; |
4d68fbe6378b
Now with Andy Gordon's treatment of freshness to replace newN/K
paulson
parents:
2451
diff
changeset
|
73 |
Addsimps [Spy_see_shrK]; |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
74 |
|
5114
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
75 |
Goal "evs : yahalom ==> (Key (shrK A) : analz (spies evs)) = (A : bad)"; |
5066
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
4831
diff
changeset
|
76 |
by Auto_tac; |
2516
4d68fbe6378b
Now with Andy Gordon's treatment of freshness to replace newN/K
paulson
parents:
2451
diff
changeset
|
77 |
qed "Spy_analz_shrK"; |
4d68fbe6378b
Now with Andy Gordon's treatment of freshness to replace newN/K
paulson
parents:
2451
diff
changeset
|
78 |
Addsimps [Spy_analz_shrK]; |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
79 |
|
4471 | 80 |
AddSDs [Spy_see_shrK RSN (2, rev_iffD1), |
81 |
Spy_analz_shrK RSN (2, rev_iffD1)]; |
|
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
82 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
83 |
|
3432 | 84 |
(*Nobody can have used non-existent keys! Needed to apply analz_insert_Key*) |
5114
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
85 |
Goal "evs : yahalom ==> \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
86 |
\ Key K ~: used evs --> K ~: keysFor (parts (spies evs))"; |
3519
ab0a9fbed4c0
Changing "lost" from a parameter of protocol definitions to a constant.
paulson
parents:
3516
diff
changeset
|
87 |
by (parts_induct_tac 1); |
2516
4d68fbe6378b
Now with Andy Gordon's treatment of freshness to replace newN/K
paulson
parents:
2451
diff
changeset
|
88 |
(*YM4: Key K is not fresh!*) |
5066
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
4831
diff
changeset
|
89 |
by (Blast_tac 3); |
2516
4d68fbe6378b
Now with Andy Gordon's treatment of freshness to replace newN/K
paulson
parents:
2451
diff
changeset
|
90 |
(*YM3*) |
4091 | 91 |
by (blast_tac (claset() addss (simpset())) 2); |
2516
4d68fbe6378b
Now with Andy Gordon's treatment of freshness to replace newN/K
paulson
parents:
2451
diff
changeset
|
92 |
(*Fake*) |
4509
828148415197
Making proofs faster, especially using keysFor_parts_insert
paulson
parents:
4477
diff
changeset
|
93 |
by (blast_tac (claset() addSDs [keysFor_parts_insert]) 1); |
2160 | 94 |
qed_spec_mp "new_keys_not_used"; |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
95 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
96 |
bind_thm ("new_keys_not_analzd", |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
97 |
[analz_subset_parts RS keysFor_mono, |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
98 |
new_keys_not_used] MRS contra_subsetD); |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
99 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
100 |
Addsimps [new_keys_not_used, new_keys_not_analzd]; |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
101 |
|
2155 | 102 |
(*Describes the form of K when the Server sends this message. Useful for |
103 |
Oops as well as main secrecy property.*) |
|
5114
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
104 |
Goal "[| Says Server A {|nb', Crypt (shrK A) {|Agent B, Key K, na|}, X|} \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
105 |
\ : set evs; \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
106 |
\ evs : yahalom |] \ |
5434
9b4bed3f394c
Got rid of not_Says_to_self and most uses of ~= in definitions and theorems
paulson
parents:
5421
diff
changeset
|
107 |
\ ==> K ~: range shrK"; |
2155 | 108 |
by (etac rev_mp 1); |
109 |
by (etac yahalom.induct 1); |
|
3121
cbb6c0c1c58a
Conversion to use blast_tac (with other improvements)
paulson
parents:
2637
diff
changeset
|
110 |
by (ALLGOALS Asm_simp_tac); |
2155 | 111 |
qed "Says_Server_message_form"; |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
112 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
113 |
|
3519
ab0a9fbed4c0
Changing "lost" from a parameter of protocol definitions to a constant.
paulson
parents:
3516
diff
changeset
|
114 |
(*For proofs involving analz.*) |
3683 | 115 |
val analz_spies_tac = |
116 |
dtac YM4_analz_spies 6 THEN |
|
3519
ab0a9fbed4c0
Changing "lost" from a parameter of protocol definitions to a constant.
paulson
parents:
3516
diff
changeset
|
117 |
forward_tac [Says_Server_message_form] 7 THEN |
2516
4d68fbe6378b
Now with Andy Gordon's treatment of freshness to replace newN/K
paulson
parents:
2451
diff
changeset
|
118 |
assume_tac 7 THEN |
4d68fbe6378b
Now with Andy Gordon's treatment of freshness to replace newN/K
paulson
parents:
2451
diff
changeset
|
119 |
REPEAT ((etac conjE ORELSE' hyp_subst_tac) 7); |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
120 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
121 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
122 |
(**** |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
123 |
The following is to prove theorems of the form |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
124 |
|
3683 | 125 |
Key K : analz (insert (Key KAB) (spies evs)) ==> |
126 |
Key K : analz (spies evs) |
|
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
127 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
128 |
A more general formula must be proved inductively. |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
129 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
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|
130 |
****) |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
131 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
132 |
(** Session keys are not used to encrypt other session keys **) |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
133 |
|
5114
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
134 |
Goal "evs : yahalom ==> \ |
5066
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
4831
diff
changeset
|
135 |
\ ALL K KK. KK <= Compl (range shrK) --> \ |
5114
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
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|
136 |
\ (Key K : analz (Key``KK Un (spies evs))) = \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
137 |
\ (K : KK | Key K : analz (spies evs))"; |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
138 |
by (etac yahalom.induct 1); |
3683 | 139 |
by analz_spies_tac; |
2516
4d68fbe6378b
Now with Andy Gordon's treatment of freshness to replace newN/K
paulson
parents:
2451
diff
changeset
|
140 |
by (REPEAT_FIRST (resolve_tac [allI, impI])); |
3961 | 141 |
by (REPEAT_FIRST (rtac analz_image_freshK_lemma)); |
2516
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Now with Andy Gordon's treatment of freshness to replace newN/K
paulson
parents:
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diff
changeset
|
142 |
by (ALLGOALS (asm_simp_tac analz_image_freshK_ss)); |
3450
cd73bc206d87
Proof tidying and variable renaming (NA->na, NB->nb when of type msg)
paulson
parents:
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diff
changeset
|
143 |
(*Fake*) |
4422
21238c9d363e
Simplified proofs using rewrites for f``A where f is injective
paulson
parents:
4238
diff
changeset
|
144 |
by (spy_analz_tac 1); |
2516
4d68fbe6378b
Now with Andy Gordon's treatment of freshness to replace newN/K
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parents:
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diff
changeset
|
145 |
qed_spec_mp "analz_image_freshK"; |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
146 |
|
5114
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parents:
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diff
changeset
|
147 |
Goal "[| evs : yahalom; KAB ~: range shrK |] ==> \ |
c729d4c299c1
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parents:
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diff
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|
148 |
\ Key K : analz (insert (Key KAB) (spies evs)) = \ |
c729d4c299c1
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parents:
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diff
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|
149 |
\ (K = KAB | Key K : analz (spies evs))"; |
2516
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Now with Andy Gordon's treatment of freshness to replace newN/K
paulson
parents:
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diff
changeset
|
150 |
by (asm_simp_tac (analz_image_freshK_ss addsimps [analz_image_freshK]) 1); |
4d68fbe6378b
Now with Andy Gordon's treatment of freshness to replace newN/K
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parents:
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diff
changeset
|
151 |
qed "analz_insert_freshK"; |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
152 |
|
81c8d46edfa3
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paulson
parents:
diff
changeset
|
153 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
154 |
(*** The Key K uniquely identifies the Server's message. **) |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
155 |
|
5114
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parents:
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diff
changeset
|
156 |
Goal "evs : yahalom ==> \ |
c729d4c299c1
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parents:
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diff
changeset
|
157 |
\ EX A' B' na' nb' X'. ALL A B na nb X. \ |
c729d4c299c1
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parents:
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diff
changeset
|
158 |
\ Says Server A \ |
c729d4c299c1
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parents:
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diff
changeset
|
159 |
\ {|nb, Crypt (shrK A) {|Agent B, Key K, na|}, X|} \ |
c729d4c299c1
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parents:
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diff
changeset
|
160 |
\ : set evs --> A=A' & B=B' & na=na' & nb=nb' & X=X'"; |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
161 |
by (etac yahalom.induct 1); |
4091 | 162 |
by (ALLGOALS (asm_simp_tac (simpset() addsimps [all_conj_distrib]))); |
3730 | 163 |
by (Clarify_tac 1); |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
164 |
(*Remaining case: YM3*) |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
165 |
by (expand_case_tac "K = ?y" 1); |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
166 |
by (REPEAT (ares_tac [refl,exI,impI,conjI] 2)); |
2516
4d68fbe6378b
Now with Andy Gordon's treatment of freshness to replace newN/K
paulson
parents:
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diff
changeset
|
167 |
(*...we assume X is a recent message and handle this case by contradiction*) |
5066
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
4831
diff
changeset
|
168 |
by (blast_tac (claset() delrules [conjI] (*prevent splitup into 4 subgoals*) |
4199 | 169 |
addss (simpset() addsimps [parts_insertI])) 1); |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
170 |
val lemma = result(); |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
171 |
|
5114
c729d4c299c1
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parents:
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changeset
|
172 |
Goal "[| Says Server A \ |
c729d4c299c1
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parents:
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changeset
|
173 |
\ {|nb, Crypt (shrK A) {|Agent B, Key K, na|}, X|} : set evs; \ |
c729d4c299c1
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parents:
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changeset
|
174 |
\ Says Server A' \ |
c729d4c299c1
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parents:
5076
diff
changeset
|
175 |
\ {|nb', Crypt (shrK A') {|Agent B', Key K, na'|}, X'|} : set evs; \ |
c729d4c299c1
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parents:
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|
176 |
\ evs : yahalom |] \ |
c729d4c299c1
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parents:
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changeset
|
177 |
\ ==> A=A' & B=B' & na=na' & nb=nb'"; |
2451
ce85a2aafc7a
Extensive tidying and simplification, largely stemming from
paulson
parents:
2377
diff
changeset
|
178 |
by (prove_unique_tac lemma 1); |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
179 |
qed "unique_session_keys"; |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
180 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
181 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
182 |
(** Crucial secrecy property: Spy does not see the keys sent in msg YM3 **) |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
183 |
|
5434
9b4bed3f394c
Got rid of not_Says_to_self and most uses of ~= in definitions and theorems
paulson
parents:
5421
diff
changeset
|
184 |
Goal "[| A ~: bad; B ~: bad; evs : yahalom |] \ |
5114
c729d4c299c1
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parents:
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diff
changeset
|
185 |
\ ==> Says Server A \ |
c729d4c299c1
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parents:
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diff
changeset
|
186 |
\ {|nb, Crypt (shrK A) {|Agent B, Key K, na|}, \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
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parents:
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diff
changeset
|
187 |
\ Crypt (shrK B) {|Agent A, Agent B, Key K, nb|}|} \ |
c729d4c299c1
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parents:
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diff
changeset
|
188 |
\ : set evs --> \ |
c729d4c299c1
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parents:
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diff
changeset
|
189 |
\ Notes Spy {|na, nb, Key K|} ~: set evs --> \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
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diff
changeset
|
190 |
\ Key K ~: analz (spies evs)"; |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
191 |
by (etac yahalom.induct 1); |
3683 | 192 |
by analz_spies_tac; |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
193 |
by (ALLGOALS |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
194 |
(asm_simp_tac |
4831 | 195 |
(simpset() addsimps split_ifs |
4686 | 196 |
addsimps [analz_insert_eq, analz_insert_freshK]))); |
3450
cd73bc206d87
Proof tidying and variable renaming (NA->na, NB->nb when of type msg)
paulson
parents:
3432
diff
changeset
|
197 |
(*Oops*) |
4091 | 198 |
by (blast_tac (claset() addDs [unique_session_keys]) 3); |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
199 |
(*YM3*) |
5066
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
4831
diff
changeset
|
200 |
by (blast_tac (claset() delrules [impCE]) 2); |
3450
cd73bc206d87
Proof tidying and variable renaming (NA->na, NB->nb when of type msg)
paulson
parents:
3432
diff
changeset
|
201 |
(*Fake*) |
cd73bc206d87
Proof tidying and variable renaming (NA->na, NB->nb when of type msg)
paulson
parents:
3432
diff
changeset
|
202 |
by (spy_analz_tac 1); |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
203 |
val lemma = result() RS mp RS mp RSN(2,rev_notE); |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
204 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
205 |
|
3432 | 206 |
(*Final version*) |
5114
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
207 |
Goal "[| Says Server A \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
208 |
\ {|nb, Crypt (shrK A) {|Agent B, Key K, na|}, \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
209 |
\ Crypt (shrK B) {|Agent A, Agent B, Key K, nb|}|} \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
210 |
\ : set evs; \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
211 |
\ Notes Spy {|na, nb, Key K|} ~: set evs; \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
212 |
\ A ~: bad; B ~: bad; evs : yahalom |] \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
213 |
\ ==> Key K ~: analz (spies evs)"; |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
214 |
by (forward_tac [Says_Server_message_form] 1 THEN assume_tac 1); |
4091 | 215 |
by (blast_tac (claset() addSEs [lemma]) 1); |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
216 |
qed "Spy_not_see_encrypted_key"; |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
217 |
|
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
218 |
|
3450
cd73bc206d87
Proof tidying and variable renaming (NA->na, NB->nb when of type msg)
paulson
parents:
3432
diff
changeset
|
219 |
(** Security Guarantee for A upon receiving YM3 **) |
2155 | 220 |
|
3432 | 221 |
(*If the encrypted message appears then it originated with the Server. |
222 |
May now apply Spy_not_see_encrypted_key, subject to its conditions.*) |
|
5114
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
223 |
Goal "[| Crypt (shrK A) {|Agent B, Key K, na|} \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
224 |
\ : parts (spies evs); \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
225 |
\ A ~: bad; evs : yahalom |] \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
226 |
\ ==> EX nb. Says Server A \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
227 |
\ {|nb, Crypt (shrK A) {|Agent B, Key K, na|}, \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
228 |
\ Crypt (shrK B) {|Agent A, Agent B, Key K, nb|}|} \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
229 |
\ : set evs"; |
2155 | 230 |
by (etac rev_mp 1); |
3519
ab0a9fbed4c0
Changing "lost" from a parameter of protocol definitions to a constant.
paulson
parents:
3516
diff
changeset
|
231 |
by (parts_induct_tac 1); |
5066
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
4831
diff
changeset
|
232 |
by (ALLGOALS Blast_tac); |
2323 | 233 |
qed "A_trusts_YM3"; |
2155 | 234 |
|
4598
649bf14debe7
Added some more explicit guarantees of key secrecy for agents
paulson
parents:
4537
diff
changeset
|
235 |
(*The obvious combination of A_trusts_YM3 with Spy_not_see_encrypted_key*) |
5114
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
236 |
Goal "[| Crypt (shrK A) {|Agent B, Key K, na|} : parts (spies evs); \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
237 |
\ ALL nb. Notes Spy {|na, nb, Key K|} ~: set evs; \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
238 |
\ A ~: bad; B ~: bad; evs : yahalom |] \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
239 |
\ ==> Key K ~: analz (spies evs)"; |
4598
649bf14debe7
Added some more explicit guarantees of key secrecy for agents
paulson
parents:
4537
diff
changeset
|
240 |
by (blast_tac (claset() addSDs [A_trusts_YM3, Spy_not_see_encrypted_key]) 1); |
649bf14debe7
Added some more explicit guarantees of key secrecy for agents
paulson
parents:
4537
diff
changeset
|
241 |
qed "A_gets_good_key"; |
649bf14debe7
Added some more explicit guarantees of key secrecy for agents
paulson
parents:
4537
diff
changeset
|
242 |
|
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
243 |
|
3450
cd73bc206d87
Proof tidying and variable renaming (NA->na, NB->nb when of type msg)
paulson
parents:
3432
diff
changeset
|
244 |
(** Security Guarantee for B upon receiving YM4 **) |
cd73bc206d87
Proof tidying and variable renaming (NA->na, NB->nb when of type msg)
paulson
parents:
3432
diff
changeset
|
245 |
|
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
246 |
(*B knows, by the first part of A's message, that the Server distributed |
5066
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
4831
diff
changeset
|
247 |
the key for A and B, and has associated it with NB.*) |
5114
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
248 |
Goal "[| Crypt (shrK B) {|Agent A, Agent B, Key K, Nonce NB|} \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
249 |
\ : parts (spies evs); \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
250 |
\ B ~: bad; evs : yahalom |] \ |
5066
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
4831
diff
changeset
|
251 |
\ ==> EX NA. Says Server A \ |
5114
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
252 |
\ {|Nonce NB, \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
253 |
\ Crypt (shrK A) {|Agent B, Key K, Nonce NA|}, \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
254 |
\ Crypt (shrK B) {|Agent A, Agent B, Key K, Nonce NB|}|} \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
255 |
\ : set evs"; |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
256 |
by (etac rev_mp 1); |
3519
ab0a9fbed4c0
Changing "lost" from a parameter of protocol definitions to a constant.
paulson
parents:
3516
diff
changeset
|
257 |
by (parts_induct_tac 1); |
5066
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
4831
diff
changeset
|
258 |
by (ALLGOALS Blast_tac); |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
259 |
qed "B_trusts_YM4_shrK"; |
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
260 |
|
3450
cd73bc206d87
Proof tidying and variable renaming (NA->na, NB->nb when of type msg)
paulson
parents:
3432
diff
changeset
|
261 |
|
cd73bc206d87
Proof tidying and variable renaming (NA->na, NB->nb when of type msg)
paulson
parents:
3432
diff
changeset
|
262 |
(*With this protocol variant, we don't need the 2nd part of YM4 at all: |
cd73bc206d87
Proof tidying and variable renaming (NA->na, NB->nb when of type msg)
paulson
parents:
3432
diff
changeset
|
263 |
Nonce NB is available in the first part.*) |
2111
81c8d46edfa3
New version of Yahalom, as recommended on p 259 of BAN paper
paulson
parents:
diff
changeset
|
264 |
|
2155 | 265 |
(*What can B deduce from receipt of YM4? Stronger and simpler than Yahalom |
266 |
because we do not have to show that NB is secret. *) |
|
5114
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
267 |
Goal "[| Says A' B {|Crypt (shrK B) {|Agent A, Agent B, Key K, Nonce NB|}, \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
5076
diff
changeset
|
268 |
\ X|} \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
paulson
parents:
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|
269 |
\ : set evs; \ |
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|
270 |
\ A ~: bad; B ~: bad; evs : yahalom |] \ |
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|
271 |
\ ==> EX NA. Says Server A \ |
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272 |
\ {|Nonce NB, \ |
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|
273 |
\ Crypt (shrK A) {|Agent B, Key K, Nonce NA|}, \ |
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|
274 |
\ Crypt (shrK B) {|Agent A, Agent B, Key K, Nonce NB|}|} \ |
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|
275 |
\ : set evs"; |
4091 | 276 |
by (blast_tac (claset() addSDs [B_trusts_YM4_shrK]) 1); |
2323 | 277 |
qed "B_trusts_YM4"; |
3432 | 278 |
|
279 |
||
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|
280 |
(*The obvious combination of B_trusts_YM4 with Spy_not_see_encrypted_key*) |
5114
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|
281 |
Goal "[| Says A' B {|Crypt (shrK B) {|Agent A, Agent B, Key K, Nonce NB|}, \ |
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|
282 |
\ X|} \ |
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|
283 |
\ : set evs; \ |
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|
284 |
\ ALL na. Notes Spy {|na, Nonce NB, Key K|} ~: set evs; \ |
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|
285 |
\ A ~: bad; B ~: bad; evs : yahalom |] \ |
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|
286 |
\ ==> Key K ~: analz (spies evs)"; |
4598
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|
287 |
by (blast_tac (claset() addSDs [B_trusts_YM4, Spy_not_see_encrypted_key]) 1); |
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|
288 |
qed "B_gets_good_key"; |
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|
289 |
|
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290 |
|
3432 | 291 |
|
292 |
(*** Authenticating B to A ***) |
|
293 |
||
294 |
(*The encryption in message YM2 tells us it cannot be faked.*) |
|
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|
295 |
Goal "[| Crypt (shrK B) {|Agent A, Nonce NA|} : parts (spies evs); \ |
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|
296 |
\ B ~: bad; evs : yahalom \ |
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|
297 |
\ |] ==> EX NB. Says B Server {|Agent B, Nonce NB, \ |
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|
298 |
\ Crypt (shrK B) {|Agent A, Nonce NA|}|} \ |
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|
299 |
\ : set evs"; |
5066
30271d90644f
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|
300 |
by (etac rev_mp 1); |
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|
301 |
by (etac rev_mp 1); |
3519
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Changing "lost" from a parameter of protocol definitions to a constant.
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|
302 |
by (parts_induct_tac 1); |
5066
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|
303 |
by (ALLGOALS Blast_tac); |
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|
304 |
qed "B_Said_YM2"; |
3432 | 305 |
|
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|
306 |
|
3432 | 307 |
(*If the server sends YM3 then B sent YM2, perhaps with a different NB*) |
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|
308 |
Goal "[| Says Server A \ |
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|
309 |
\ {|nb, Crypt (shrK A) {|Agent B, Key K, Nonce NA|}, X|} \ |
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|
310 |
\ : set evs; \ |
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|
311 |
\ B ~: bad; evs : yahalom \ |
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|
312 |
\ |] ==> EX nb'. Says B Server {|Agent B, nb', \ |
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|
313 |
\ Crypt (shrK B) {|Agent A, Nonce NA|}|} \ |
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|
314 |
\ : set evs"; |
5066
30271d90644f
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|
315 |
by (etac rev_mp 1); |
30271d90644f
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|
316 |
by (etac rev_mp 1); |
3432 | 317 |
by (etac yahalom.induct 1); |
318 |
by (ALLGOALS Asm_simp_tac); |
|
319 |
(*YM3*) |
|
5066
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|
320 |
by (blast_tac (claset() addSDs [B_Said_YM2]) 3); |
3432 | 321 |
(*Fake, YM2*) |
322 |
by (ALLGOALS Blast_tac); |
|
5066
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|
323 |
val lemma = result(); |
3432 | 324 |
|
325 |
(*If A receives YM3 then B has used nonce NA (and therefore is alive)*) |
|
5114
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|
326 |
Goal "[| Says S A {|nb, Crypt (shrK A) {|Agent B, Key K, Nonce NA|}, X|} \ |
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|
327 |
\ : set evs; \ |
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|
328 |
\ A ~: bad; B ~: bad; evs : yahalom |] \ |
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|
329 |
\==> EX nb'. Says B Server \ |
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|
330 |
\ {|Agent B, nb', Crypt (shrK B) {|Agent A, Nonce NA|}|} \ |
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|
331 |
\ : set evs"; |
5066
30271d90644f
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|
332 |
by (blast_tac (claset() addSDs [A_trusts_YM3, lemma]) 1); |
3432 | 333 |
qed "YM3_auth_B_to_A"; |
334 |
||
335 |
||
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diff
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|
336 |
(*** Authenticating A to B using the certificate Crypt K (Nonce NB) ***) |
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|
337 |
|
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Proof tidying and variable renaming (NA->na, NB->nb when of type msg)
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parents:
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diff
changeset
|
338 |
(*Assuming the session key is secure, if both certificates are present then |
3432 | 339 |
A has said NB. We can't be sure about the rest of A's message, but only |
5066
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
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parents:
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changeset
|
340 |
NB matters for freshness. Note that Key K ~: analz (spies evs) must be |
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
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parents:
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|
341 |
the FIRST antecedent of the induction formula.*) |
5114
c729d4c299c1
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|
342 |
Goal "evs : yahalom \ |
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|
343 |
\ ==> Key K ~: analz (spies evs) --> \ |
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changeset
|
344 |
\ Crypt K (Nonce NB) : parts (spies evs) --> \ |
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changeset
|
345 |
\ Crypt (shrK B) {|Agent A, Agent B, Key K, Nonce NB|} \ |
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|
346 |
\ : parts (spies evs) --> \ |
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|
347 |
\ B ~: bad --> \ |
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|
348 |
\ (EX X. Says A B {|X, Crypt K (Nonce NB)|} : set evs)"; |
3519
ab0a9fbed4c0
Changing "lost" from a parameter of protocol definitions to a constant.
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parents:
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diff
changeset
|
349 |
by (parts_induct_tac 1); |
3432 | 350 |
(*Fake*) |
5066
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
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changeset
|
351 |
by (Blast_tac 1); |
3432 | 352 |
(*YM3: by new_keys_not_used we note that Crypt K (Nonce NB) could not exist*) |
4238
679a233fb206
Crypt_imp_keysFor: version of Crypt_imp_invKey_keysFor for shared keys
paulson
parents:
4199
diff
changeset
|
353 |
by (fast_tac (claset() addSDs [Crypt_imp_keysFor] addss (simpset())) 1); |
3450
cd73bc206d87
Proof tidying and variable renaming (NA->na, NB->nb when of type msg)
paulson
parents:
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diff
changeset
|
354 |
(*YM4: was Crypt K (Nonce NB) the very last message? If not, use ind. hyp.*) |
4091 | 355 |
by (asm_simp_tac (simpset() addsimps [ex_disj_distrib]) 1); |
3450
cd73bc206d87
Proof tidying and variable renaming (NA->na, NB->nb when of type msg)
paulson
parents:
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diff
changeset
|
356 |
(*yes: apply unicity of session keys*) |
3683 | 357 |
by (not_bad_tac "Aa" 1); |
5066
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
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diff
changeset
|
358 |
by (blast_tac (claset() addSDs [A_trusts_YM3, B_trusts_YM4_shrK] |
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
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changeset
|
359 |
addDs [unique_session_keys]) 1); |
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
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diff
changeset
|
360 |
qed_spec_mp "Auth_A_to_B_lemma"; |
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
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diff
changeset
|
361 |
|
3432 | 362 |
|
363 |
(*If B receives YM4 then A has used nonce NB (and therefore is alive). |
|
3450
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Proof tidying and variable renaming (NA->na, NB->nb when of type msg)
paulson
parents:
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diff
changeset
|
364 |
Moreover, A associates K with NB (thus is talking about the same run). |
3432 | 365 |
Other premises guarantee secrecy of K.*) |
5114
c729d4c299c1
Deleted leading parameters thanks to new Goal command
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diff
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|
366 |
Goal "[| Says A' B {|Crypt (shrK B) {|Agent A, Agent B, Key K, Nonce NB|}, \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
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|
367 |
\ Crypt K (Nonce NB)|} : set evs; \ |
c729d4c299c1
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|
368 |
\ (ALL NA. Notes Spy {|Nonce NA, Nonce NB, Key K|} ~: set evs); \ |
c729d4c299c1
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|
369 |
\ A ~: bad; B ~: bad; evs : yahalom |] \ |
c729d4c299c1
Deleted leading parameters thanks to new Goal command
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diff
changeset
|
370 |
\ ==> EX X. Says A B {|X, Crypt K (Nonce NB)|} : set evs"; |
5066
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
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diff
changeset
|
371 |
by (subgoal_tac "Key K ~: analz (spies evs)" 1); |
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
4831
diff
changeset
|
372 |
by (blast_tac (claset() addIs [Auth_A_to_B_lemma]) 1); |
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
4831
diff
changeset
|
373 |
by (blast_tac (claset() addDs [Spy_not_see_encrypted_key, |
30271d90644f
Changed format of Bob's certificate from Nb,K,A to A,B,K,Nb.
paulson
parents:
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diff
changeset
|
374 |
B_trusts_YM4_shrK]) 1); |
3432 | 375 |
qed_spec_mp "YM4_imp_A_Said_YM3"; |