When we are indexing, we should treat SignedData parts the same way
that we treat a multipart object, indexing the wrapped part as a
distinct MIME object.
Unfortunately, this means doing some sort of cryptographic
verification whose results we throw away, because GMime doesn't offer
us any way to unwrap without doing signature verification.
I've opened https://github.com/jstedfast/gmime/issues/67 to request
the capability from GMime but for now, we'll just accept the
additional performance hit.
As we do this indexing, we also apply the "signed" tag, by analogy
with how we handle multipart/signed messages. These days, that kind
of change should probably be done with a property instead, but that's
a different set of changes. This one is just for consistency.
Note that we are currently *only* handling signedData parts, which are
basically clearsigned messages. PKCS#7 parts can also be
envelopedData and authEnvelopedData (which are effectively encryption
layers), and compressedData (which afaict isn't implemented anywhere,
i've never encountered it). We're laying the groundwork for indexing
these other S/MIME types here, but we're only dealing with signedData
for now.
Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
When checking cryptographic signatures, Notmuch relies on GMime to
tell it whether the certificate that signs a message has a valid User
ID or not.
If the User ID is not valid, then notmuch does not report the signer's
User ID to the user. This means that the consumer of notmuch's
cryptographic summary of a message (or of its protected headers) can
be confident in relaying the reported identity to the user.
However, some versions of GMime before 3.2.7 cannot report Certificate
validity for X.509 certificates. This is resolved upstream in GMime
at https://github.com/jstedfast/gmime/pull/90.
We adapt to this by marking tests of reported User IDs for
S/MIME-signed messages as known-broken if GMime is older than 3.2.7
and has not been patched.
If GMime >= 3.2.7 and certificate validity still doesn't work for
X.509 certs, then there has likely been a regression in GMime and we
should fail early, during ./configure.
To break out these specific User ID checks from other checks, i had to
split some tests into two parts, and reuse $output across the two
subtests.
Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
Add a simple S/MIME SignedData message, taken from an upcoming draft
of
https://datatracker.ietf.org/doc/draft-autocrypt-lamps-protected-headers/
RFC 8551 describes a SignedData, a one-part clearsigned object that is
more resistant to common patterns of MTA message munging than
multipart/signed (but has the downside that it is only readable by
clients that implement S/MIME).
To make sure sure notmuch can handle this kind of object, we want to
know a few things:
Already working:
- Is the content of the SignedData object indexed? It actually is
right now because of dumb luck -- i think we're indexing the raw
CMS object and it happens to contain the cleartext of the message
in a way that we can consume it before passing it on to Xapian.
- Are we accidentally indexing the embedded PKCS#7 certificates? We
don't want to, and for some reason I don't understand, our indexing
is actually skipping the embedded certificates already. That's
good!
Still need fixing:
- do we know the MIME type of the embedded part?
- do we know that the message is signed?
- can notmuch-show read its content?
- can notmuch-show indicate the signature validity?
- can notmuch-reply properly quote and attribute content?
Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
These tests describe some simple behavior we would expect to work if
we were to correctly index the cleartext of encrypted S/MIME messages
(PKCS#7 envelopedData).
Of course, they don't currently pass, so we mark them known-broken.
Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
When consuming a signed+encrypted S/MIME message generated by emacs,
we expect to see the same cryptographic properties for the message as
a whole. This is not done correctly yet, so the test is marked as
known broken.
Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
No functional change.
We no longer need to identify the key and cert to mml-mode when
sending an S/MIME message, so making a copy of key+cert.pem to
test_suite.pem is superfluous. Get rid of the extra file.
Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
The documentation for message mode clearly states that EasyPG (which
uses GnuPG) is the default and recommended way to use S/MIME with
mml-secure:
[0] https://www.gnu.org/software/emacs/manual/html_node/message/Using-S_002fMIME.html
To ensure that this mode works, we just need to import the secret key
in question into gpgsm in addition to the public key. gpgsm should be
able pick the right keys+certificates to use based on To/From headers,
so we don't have to specify anything manually in the #secure mml tag.
The import process from the OpenSSL-preferred form (cert+secretkey) is
rather ugly, because gpgsm wants to see a PKCS#12 object when
importing secret keys.
Note that EasyPG generates the more modern Content-Type:
application/pkcs7-signature instead of application/x-pkcs7-signature
for the detached signature.
We are also obliged to manually set gpgsm's include-certs setting to 1
because gpgsm defaults to send "everything but the root cert". In our
weird test case, the certificate we're using is self-signed, so it
*is* the root cert, which means that gpgsm doesn't include it by
default. Setting it to 1 forces inclusion of the signer's cert, which
satisfies openssl's smime subcommand. See https://dev.gnupg.org/T4878
for more details.
Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
This allows MUAs that don't want to think about per-mime-part
cryptographic status to have a simple high-level overview of the
message's cryptographic state.
Sensibly structured encrypted and/or signed messages will work fine
with this. The only requirement for the simplest encryption + signing
is that the message have all of its encryption and signing protection
(the "cryptographic envelope") in a contiguous set of MIME layers at
the very outside of the message itself.
This is because messages with some subparts signed or encrypted, but
with other subparts with no cryptographic protection is very difficult
to reason about, and even harder for the user to make sense of or work
with.
For further characterization of the Cryptographic Envelope and some of
the usability tradeoffs, see here:
https://dkg.fifthhorseman.net/blog/e-mail-cryptography.html#cryptographic-envelope
When i'm trying to understand a message signature, i care that i know
who it came from (the "validity" of the identity associated with the
key), *not* whether i'm willing to accept the keyholder's other
identity assertions (the "trust" associated with the certificate).
We've been reporting User ID information based on the "trust"
associated with the certificate, because GMime didn't clearly expose
the validity of the User IDs.
This change relies on fixes made in GMime 3.0.3 and later which
include https://github.com/jstedfast/gmime/pull/18.
Since the error field is unused by the emacs front end, no changes are
needed other than bumping the format version number.
As it is, this is a bit overengineered, but it will reduce duplication
when we support gmime 3.0
Since gnupg 2.1.20, gpg-agent no longer shut itself down when
$GNUPGHOME directory is removed.
Add exit hooks to the test modules which execute `gpgconf --kill all`
Add exit hooks to execute `gpgconf --kill all` in the modules that
create $GNUPGHOME for gpg to work with.
Unify the subtests by requiring test_begin_subtest before
test_expect_success. (Similar change for test_expect_code will
follow.)
This increases clarity in the test scripts by having a separate line
for the start of the subtest with the heading, and makes it possible
to simplify the test infrastructure by making all subtests similar.
Instead of just having the first filename for the message, list all
duplicate filenames of the message as a list in the formatted
outputs. This bumps the format version to 3.
GnuPG 2.1.16 is now injecting the full issuer fingerprint in its
signatures, which makes them about 32 octets larger when
ascii-armored.
This change in size means that the size of the MIME parts will vary
depending on the version of gpg that the user has installed. at any
rate, the signature part should be non-zero (this is true for
basically any MIME part), so we just test for that instead of an exact
size.
notmuch-show --verify will now also process S/MIME multiparts if
encountered. Requires gmime-2.6 and gpgsm.
Based on work by Jameson Graef Rollins <jrollins@finestructure.net>.
The test is pretty much cut and paste from the PGP/MIME version, with
obvious updates taken from notmuch output. This also requires setting
up gpgsm infrastucture.
Test the ability of notmuch-mua-mail to send S/MIME signed (and
encrypted) messages; this really relies on existing functionality in
message-mode.
The generated keys and messages will later be useful for testing the
notmuch CLI.
