[PATCH] test: signature verification during decryption (session keys)

[Daniel Kahn Gillmor]

When the user knows the signer's key, we want "notmuch show" to be
able to verify the signature of an encrypted and signed message
regardless of whether we are using a stashed session key or not.

I wrote this test because I was surprised to see signature
verification failing when viewing some encrypted messages after
upgrading to GPGME 1.13.0-1 in debian experimental.

The added tests here all pass with GPGME 1.12.0, but the final test
fails with 1.13.0, due to some buggy updates to GPGME upstream: see
https://dev.gnupg.org/T3464 for more details.

While the bug needs to be fixed in GPGME, notmuch's test suite needs
to make sure that GMime is doing what we expect it to do; i was a bit
surprised that it hadn't caught the problem, hence this patch.

I've fixed this bug in debian experimental with gpgme 1.13.0-2, so the
tests should pass on any debian system.  I've also fixed it in the
gpgme packages (1.13.0-2~ppa1) in the ubuntu xenial PPA
(ppa:notmuch/notmuch) that notmuch uses for Travis CI.

Signed-off-by: Daniel Kahn Gillmor <dkg at fifthhorseman.net>
---
 test/T357-index-decryption.sh            | 19 +++++++++++++
 test/corpora/crypto/encrypted-signed.eml | 35 ++++++++++++++++++++++++
 2 files changed, 54 insertions(+)
 create mode 100644 test/corpora/crypto/encrypted-signed.eml

diff --git a/test/T357-index-decryption.sh b/test/T357-index-decryption.sh
index 8a2d4c02..1ac2836a 100755
--- a/test/T357-index-decryption.sh
+++ b/test/T357-index-decryption.sh
@@ -226,6 +226,7 @@ output=$(notmuch dump | LC_ALL=C sort)
 expected='#= simple-encrypted at crypto.notmuchmail.org index.decryption=failure
 #notmuch-dump batch-tag:3 config,properties,tags
 +encrypted +inbox +unread -- id:basic-encrypted at crypto.notmuchmail.org
++encrypted +inbox +unread -- id:encrypted-signed at crypto.notmuchmail.org
 +encrypted +inbox +unread -- id:simple-encrypted at crypto.notmuchmail.org'
 test_expect_equal \
     "$output" \
@@ -288,6 +289,24 @@ test_expect_equal \
     "$output" \
     "$expected"
 
+goodsig='good_sig:[0][0][0]["crypto"]["signed"]["status"][0]["status"]="good"'
+nosig='no_sig:[0][0][0]["crypto"]!"signed"'
+
+test_begin_subtest "verify signature without a session key stashed when --decrypt=true"
+output=$(notmuch show --format=json --decrypt=true id:encrypted-signed at crypto.notmuchmail.org)
+test_json_nodes <<<"$output" "$goodsig"
+
+test_begin_subtest "do not verify sig without a session key stashed if --decrypt=auto"
+output=$(notmuch show --format=json id:encrypted-signed at crypto.notmuchmail.org)
+test_json_nodes <<<"$output" "$nosig"
+
+test_begin_subtest "verify signature when --decrypt=stash"
+output=$(notmuch show --format=json --decrypt=stash id:encrypted-signed at crypto.notmuchmail.org)
+test_json_nodes <<<"$output" "$goodsig"
+
+test_begin_subtest "verify signature with stashed session key"
+output=$(notmuch show --format=json id:encrypted-signed at crypto.notmuchmail.org)
+test_json_nodes <<<"$output" "$goodsig"
 
 # TODO: test removal of a message from the message store between
 # indexing and reindexing.
diff --git a/test/corpora/crypto/encrypted-signed.eml b/test/corpora/crypto/encrypted-signed.eml
new file mode 100644
index 00000000..0345e3e9
--- /dev/null
+++ b/test/corpora/crypto/encrypted-signed.eml
@@ -0,0 +1,35 @@
+From: test_suite at notmuchmail.org
+To: test_suite at notmuchmail.org
+Subject: Lyrics
+Date: Wed 29 May 2019 06:09:22 PM EDT
+Message-ID: <encrypted-signed at crypto.notmuchmail.org>
+MIME-Version: 1.0
+Content-Type: multipart/encrypted; boundary="=-=-=";
+	protocol="application/pgp-encrypted"
+
+--=-=-=
+Content-Type: application/pgp-encrypted
+
+Version: 1
+
+--=-=-=
+Content-Type: application/octet-stream
+
+-----BEGIN PGP MESSAGE-----
+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+=x12v
+-----END PGP MESSAGE-----
+--=-=-=--
-- 
2.20.1