mirror of git://git.gnupg.org/gnupg.git
318 lines
10 KiB
Scheme
Executable File
318 lines
10 KiB
Scheme
Executable File
#!/usr/bin/env gpgscm
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;; Copyright (C) 2016 g10 Code GmbH
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;;
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;; This file is part of GnuPG.
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;;
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;; GnuPG is free software; you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation; either version 3 of the License, or
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;; (at your option) any later version.
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;;
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;; GnuPG is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;;
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;; You should have received a copy of the GNU General Public License
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;; along with this program; if not, see <http://www.gnu.org/licenses/>.
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(load (with-path "defs.scm"))
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(setup-environment)
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;; Redefine GPG without --always-trust and a fixed time.
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(define GPG `(,(tool 'gpg) --no-permission-warning
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--faked-system-time=1466684990))
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(define GNUPGHOME (getenv "GNUPGHOME"))
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(if (string=? "" GNUPGHOME)
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(error "GNUPGHOME not set"))
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(catch (skip "Tofu not supported")
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(call-check `(,@GPG --trust-model=tofu --list-config)))
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(define KEYS '("2183839A" "BC15C85A" "EE37CF96"))
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;; Import the test keys.
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(call-check `(,@GPG --import ,(in-srcdir "tofu-keys.asc")))
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;; Make sure the keys are imported.
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(for-each (lambda (keyid)
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(catch (error "Missing key" keyid)
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(call-check `(,@GPG --list-keys ,keyid))))
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KEYS)
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;; Get tofu policy for KEYID. Any remaining arguments are simply
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;; passed to GPG.
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;;
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;; This function only supports keys with a single user id.
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(define (getpolicy keyid . args)
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(let ((policy
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(list-ref (assoc "tfs" (gpg-with-colons
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`(--trust-model=tofu --with-tofu-info
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,@args
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--list-keys ,keyid))) 5)))
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(unless (member policy '("auto" "good" "unknown" "bad" "ask"))
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(error "Bad policy:" policy))
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policy))
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;; Check that KEYID's tofu policy matches EXPECTED-POLICY. Any
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;; remaining arguments are simply passed to GPG.
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;;
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;; This function only supports keys with a single user id.
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(define (checkpolicy keyid expected-policy . args)
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(let ((policy (apply getpolicy `(,keyid ,@args))))
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(unless (string=? policy expected-policy)
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(error keyid ": Expected policy to be" expected-policy
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"but got" policy))))
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;; Get the trust level for KEYID. Any remaining arguments are simply
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;; passed to GPG.
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;;
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;; This function only supports keys with a single user id.
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(define (gettrust keyid . args)
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(let ((trust
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(list-ref (assoc "pub" (gpg-with-colons
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`(--trust-model=tofu
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,@args
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--list-keys ,keyid))) 1)))
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(unless (and (= 1 (string-length trust))
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(member (string-ref trust 0) (string->list "oidreqnmfuws-")))
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(error "Bad trust value:" trust))
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trust))
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;; Check that KEYID's trust level matches EXPECTED-TRUST. Any
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;; remaining arguments are simply passed to GPG.
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;;
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;; This function only supports keys with a single user id.
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(define (checktrust keyid expected-trust . args)
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(let ((trust (apply gettrust `(,keyid ,@args))))
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(unless (string=? trust expected-trust)
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(error keyid ": Expected trust to be" expected-trust
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"but got" trust))))
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;; Set key KEYID's policy to POLICY. Any remaining arguments are
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;; passed as options to gpg.
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(define (setpolicy keyid policy . args)
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(call-check `(,@GPG --trust-model=tofu ,@args
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--tofu-policy ,policy ,keyid)))
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(info "Checking tofu policies and trust...")
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;; Carefully remove the TOFU db.
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(catch '() (unlink (string-append GNUPGHOME "/tofu.db")))
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;; Verify a message. There should be no conflict and the trust
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;; policy should be set to auto.
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(call-check `(,@GPG --trust-model=tofu
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--verify ,(in-srcdir "tofu-2183839A-1.txt")))
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(checkpolicy "2183839A" "auto")
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;; Check default trust.
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(checktrust "2183839A" "m")
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;; Trust should be derived lazily. Thus, if the policy is set to
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;; auto and we change --tofu-default-policy, then the trust should
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;; change as well. Try it.
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(checktrust "2183839A" "f" '--tofu-default-policy=good)
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(checktrust "2183839A" "-" '--tofu-default-policy=unknown)
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(checktrust "2183839A" "n" '--tofu-default-policy=bad)
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;; Change the policy to something other than auto and make sure the
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;; policy and the trust are correct.
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(for-each-p
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"Setting a fixed policy..."
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(lambda (policy)
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(let ((expected-trust
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(cond
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((string=? "good" policy) "f")
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((string=? "unknown" policy) "-")
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(else "n"))))
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(setpolicy "2183839A" policy)
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;; Since we have a fixed policy, the trust level shouldn't
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;; change if we change the default policy.
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(for-each-p
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""
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(lambda (default-policy)
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(checkpolicy "2183839A" policy
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'--tofu-default-policy default-policy)
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(checktrust "2183839A" expected-trust
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'--tofu-default-policy default-policy))
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'("auto" "good" "unknown" "bad" "ask"))))
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'("good" "unknown" "bad"))
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;; BC15C85A conflicts with 2183839A. On conflict, this will set
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;; BC15C85A to ask. If 2183839A is auto (it's not, it's bad), then
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;; it will be set to ask.
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(call-check `(,@GPG --trust-model=tofu
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--verify ,(in-srcdir "tofu-BC15C85A-1.txt")))
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(checkpolicy "BC15C85A" "ask")
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(checkpolicy "2183839A" "bad")
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;; EE37CF96 conflicts with 2183839A and BC15C85A. We change
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;; BC15C85A's policy to auto and leave 2183839A's policy at bad.
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;; This conflict should cause BC15C85A's policy to be changed to
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;; ask (since it is auto), but not affect 2183839A's policy.
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(setpolicy "BC15C85A" "auto")
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(checkpolicy "BC15C85A" "auto")
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(call-check `(,@GPG --trust-model=tofu
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--verify ,(in-srcdir "tofu-EE37CF96-1.txt")))
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(checkpolicy "BC15C85A" "ask")
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(checkpolicy "2183839A" "bad")
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(checkpolicy "EE37CF96" "ask")
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;; Check that we detect the following attack:
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;;
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;; Alice and Bob each have a key and cross sign them. Bob then adds a
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;; new user id, "Alice". TOFU should now detect a conflict, because
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;; Alice only signed Bob's "Bob" user id.
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(display "Checking cross sigs...\n")
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(define GPG `(,(tool 'gpg) --no-permission-warning
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--faked-system-time=1476304861))
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;; Carefully remove the TOFU db.
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(catch '() (unlink (string-append GNUPGHOME "/tofu.db")))
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(define DIR "tofu/cross-sigs")
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;; The test keys.
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(define KEYA "1938C3A0E4674B6C217AC0B987DB2814EC38277E")
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(define KEYB "DC463A16E42F03240D76E8BA8B48C6BD871C2247")
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(define KEYIDA (substring KEYA (- (string-length KEYA) 8)))
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(define KEYIDB (substring KEYB (- (string-length KEYB) 8)))
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(define (verify-messages)
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(for-each
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(lambda (key)
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(for-each
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(lambda (i)
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(let ((fn (in-srcdir DIR (string-append key "-" i ".txt"))))
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(call-check `(,@GPG --trust-model=tofu --verify ,fn))))
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(list "1" "2")))
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(list KEYIDA KEYIDB)))
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;; Import the public keys.
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(display " > Two keys. ")
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(call-check `(,@GPG --import ,(in-srcdir DIR (string-append KEYIDA "-1.gpg"))))
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(call-check `(,@GPG --import ,(in-srcdir DIR (string-append KEYIDB "-1.gpg"))))
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;; Make sure the tofu engine registers the keys.
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(verify-messages)
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(display "<\n")
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;; Since there is no conflict, the policy should be auto.
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(checkpolicy KEYA "auto")
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(checkpolicy KEYB "auto")
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;; Import the cross sigs.
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(display " > Adding cross signatures. ")
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(call-check `(,@GPG --import ,(in-srcdir DIR (string-append KEYIDA "-2.gpg"))))
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(call-check `(,@GPG --import ,(in-srcdir DIR (string-append KEYIDB "-2.gpg"))))
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(verify-messages)
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(display "<\n")
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;; There is still no conflict, so the policy shouldn't have changed.
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(checkpolicy KEYA "auto")
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(checkpolicy KEYB "auto")
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;; Import the conflicting user id.
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(display " > Adding conflicting user id. ")
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(call-check `(,@GPG --import ,(in-srcdir DIR (string-append KEYIDB "-3.gpg"))))
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(verify-messages)
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(display "<\n")
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(checkpolicy KEYA "ask")
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(checkpolicy KEYB "ask")
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;; Import Alice's signature on the conflicting user id.
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(display " > Adding cross signature on user id. ")
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(call-check `(,@GPG --import ,(in-srcdir DIR (string-append KEYIDB "-4.gpg"))))
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(verify-messages)
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(display "<\n")
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(checkpolicy KEYA "auto")
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(checkpolicy KEYB "auto")
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;; Remove the keys.
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(call-check `(,@GPG --delete-key ,KEYA))
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(call-check `(,@GPG --delete-key ,KEYB))
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;; Check that we detect the following attack:
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;;
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;; Alice has an ultimately trusted key and she signs Bob's key. Then
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;; Bob adds a new user id, "Alice". TOFU should now detect a
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;; conflict, because Alice only signed Bob's "Bob" user id.
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(display "Checking UTK sigs...\n")
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(define GPG `(,(tool 'gpg) --no-permission-warning
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--faked-system-time=1476304861))
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;; Carefully remove the TOFU db.
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(catch '() (unlink (string-append GNUPGHOME "/tofu.db")))
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(define DIR "tofu/cross-sigs")
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;; The test keys.
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(define KEYA "1938C3A0E4674B6C217AC0B987DB2814EC38277E")
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(define KEYB "DC463A16E42F03240D76E8BA8B48C6BD871C2247")
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(define KEYIDA (substring KEYA (- (string-length KEYA) 8)))
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(define KEYIDB (substring KEYB (- (string-length KEYB) 8)))
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(define (verify-messages)
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(for-each
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(lambda (key)
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(for-each
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(lambda (i)
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(let ((fn (in-srcdir DIR (string-append key "-" i ".txt"))))
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(call-check `(,@GPG --trust-model=tofu --verify ,fn))))
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(list "1" "2")))
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(list KEYIDA KEYIDB)))
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;; Import the public keys.
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(display " > Two keys. ")
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(call-check `(,@GPG --import ,(in-srcdir DIR (string-append KEYIDA "-1.gpg"))))
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(call-check `(,@GPG --import ,(in-srcdir DIR (string-append KEYIDB "-1.gpg"))))
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(display "<\n")
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;; Import the cross sigs.
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(display " > Adding cross signatures. ")
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(call-check `(,@GPG --import ,(in-srcdir DIR (string-append KEYIDA "-2.gpg"))))
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(call-check `(,@GPG --import ,(in-srcdir DIR (string-append KEYIDB "-2.gpg"))))
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(display "<\n")
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;; Make KEYA ultimately trusted.
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(display (string-append " > Marking " KEYA " as ultimately trusted. "))
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(pipe:do
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(pipe:echo (string-append KEYA ":6:\n"))
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(pipe:gpg `(--import-ownertrust)))
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(display "<\n")
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;; An ultimately trusted key's policy is good.
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(checkpolicy KEYA "good")
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;; A key signed by a UTK for which there is no policy gets the default
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;; policy of good.
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(checkpolicy KEYB "good")
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;; Import the conflicting user id.
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(display " > Adding conflicting user id. ")
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(call-check `(,@GPG --import ,(in-srcdir DIR (string-append KEYIDB "-3.gpg"))))
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(verify-messages)
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(display "<\n")
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(checkpolicy KEYA "good")
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(checkpolicy KEYB "ask")
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;; Import Alice's signature on the conflicting user id.
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(display " > Adding cross signature on user id. ")
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(call-check `(,@GPG --import ,(in-srcdir DIR (string-append KEYIDB "-4.gpg"))))
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(verify-messages)
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(display "<\n")
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(checkpolicy KEYA "good")
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(checkpolicy KEYB "good")
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;; Remove the keys.
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(call-check `(,@GPG --delete-key ,KEYA))
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(call-check `(,@GPG --delete-key ,KEYB))
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