If you're going to store the cleartext index of an encrypted message,
in most situations you might just as well store the session key.
Doing this storage has efficiency and recoverability advantages.
Combined with a schedule of regular OpenPGP subkey rotation and
destruction, this can also offer security benefits, like "deletable
e-mail", which is the store-and-forward analog to "forward secrecy".
But wait, i hear you saying, i have a special need to store cleartext
indexes but it's really bad for me to store session keys! Maybe
(let's imagine) i get lots of e-mails with incriminating photos
attached, and i want to be able to search for them by the text in the
e-mail, but i don't want someone with access to the index to be
actually able to see the photos themselves.
Fret not, the next patch in this series will support your wacky
uncommon use case.
There are some situations where the user wants to get rid of the
cleartext index of a message. For example, if they're indexing
encrypted messages normally, but suddenly they run across a message
that they really don't want any trace of in their index.
In that case, the natural thing to do is:
notmuch reindex --decrypt=false id:whatever@example.biz
But of course, clearing the cleartext index without clearing the
stashed session key is just silly. So we do the expected thing and
also destroy any stashed session keys while we're destroying the index
of the cleartext.
Note that stashed session keys are stored in the xapian database, but
xapian does not currently allow safe deletion (see
https://trac.xapian.org/ticket/742).
As a workaround, after removing session keys and cleartext material
from the database, the user probably should do something like "notmuch
compact" to try to purge whatever recoverable data is left in the
xapian freelist. This problem really needs to be addressed within
xapian, though, if we want it fixed right.
The new "auto" decryption policy is not only good for "notmuch show"
and "notmuch reindex". It's also useful for indexing messages --
there's no good reason to not try to go ahead and index the cleartext
of a message that we have a stashed session key for.
This change updates the defaults and tunes the test suite to make sure
that they have taken effect.
The stashed session keys are stored internally as notmuch properties.
So a user or developer who is reading about those properties might
want to understand how they fit into the bigger picture.
Note here that decrypting with a stored session key no longer needs
-decrypt for "notmuch show" and "notmuch reply".
When showing a message, if the user doesn't specify --decrypt= at all,
but a stashed session key is known to notmuch, notmuch should just go
ahead and try to decrypt the message with the session key (without
bothering the user for access to their asymmetric secret key).
The user can disable this at the command line with --decrypt=false if
they really don't want to look at the e-mail that they've asked
notmuch to show them.
and of course, "notmuch show --decrypt" still works for accessing the
user's secret keys if necessary.
If the user doesn't specify --decrypt= at all, but a stashed session
key is known to notmuch, when replying to an encrypted message,
notmuch should just go ahead and decrypt.
The user can disable this at the command line with --decrypt=false,
though it's not clear why they would ever want to do that.
This new automatic decryption policy should make it possible to
decrypt messages that we have stashed session keys for, without
incurring a call to the user's asymmetric keys.
the command-line interface for indexing (reindex, new, insert) used
--try-decrypt; and the configuration records used index.try_decrypt.
But by comparison with "show" and "reply", there doesn't seem to be
any reason for the "try" prefix.
This changeset adjusts the command-line interface and the
configuration interface.
For the moment, i've left indexopts_{set,get}_try_decrypt alone. The
subsequent changeset will address those.
When doing any decryption, if the notmuch database knows of any
session keys associated with the message in question, try them before
defaulting to using default symmetric crypto.
This changeset does the primary work in _notmuch_crypto_decrypt, which
grows some new parameters to handle it.
The primary advantage this patch offers is a significant speedup when
rendering large encrypted threads ("notmuch show") if session keys
happen to be cached.
Additionally, it permits message composition without access to
asymmetric secret keys ("notmuch reply"); and it permits recovering a
cleartext index when reindexing after a "notmuch restore" for those
messages that already have a session key stored.
Note that we may try multiple decryptions here (e.g. if there are
multiple session keys in the database), but we will ignore and throw
away all the GMime errors except for those that come from last
decryption attempt. Since we don't necessarily know at the time of
the decryption that this *is* the last decryption attempt, we'll ask
for the errors each time anyway.
This does nothing if no session keys are stashed in the database,
which is fine. Actually stashing session keys in the database will
come as a subsequent patch.
Now that it's easy to add argument specific modifiers in opt
descriptions, add a new .allow_empty field to allow empty strings for
individual string arguments while retaining strict checks
elsewhere. Use this for notmuch insert --folder, where the empty
string means top level folder.
Enable override of the index.try_decrypt setting on a per-run basis
when invoking "notmuch reindex". This allows the possibility of (for
example) an emacs keybinding that adds the cleartext of the currently
shown decrypted message to the index, making it searchable in the
future.
It also enables one-time indexing of all messages matching some query,
like so:
notmuch reindex tag:encrypted and\
not property:index.decryption=success and\
from:alice@example.org
We also update the documentation and tab completion, and add a few
more tests.
Enable override of the index.try_decrypt setting on a per-message
basis when invoking "notmuch insert".
We also update the documentation and tab completion, and add more tests.
Enable override of the index.try_decrypt setting during "notmuch new"
on a per-invocation basis.
We update the documentation and tab completion, and also add a test.
By default, notmuch won't try to decrypt on indexing. With this
patch, we make it possible to indicate a per-database preference using
the config variable "index.try_decrypt", which by default will be
false.
At indexing time, the database needs some way to know its internal
defaults for how to index encrypted parts. It shouldn't be contingent
on an external config file (since that can't be retrieved from the
database object itself), so we store it in the database.
This behaves similarly to the query.* configurations, which are also
stored in the database itself, so we're not introducing any new
dependencies by requiring that it be stored in the database.
QUERY_STRING was only used in two places, both to test whether a
variable should be stored in (or retrieved from) the database.
Since other configuration variables might be stored in the database in
the future, consolidate that test into a single function.
We also document that these configuration options should not be placed
in the config file.
If we see index options that ask us to decrypt when indexing a
message, and we encounter an encrypted part, we'll try to descend into
it.
If we can decrypt, we add the property index.decryption=success.
If we can't decrypt (or recognize the encrypted type of mail), we add
the property index.decryption=failure.
Note that a single message may have both values of the
"index.decryption" property: "success" and "failure". For example,
consider a message that includes multiple layers of encryption. If we
manage to decrypt the outer layer ("index.decryption=success"), but
fail on the inner layer ("index.decryption=failure").
Because of the property name, this will be automatically cleared (and
possibly re-set) during re-indexing. This means it will subsequently
correspond to the actual semantics of the stored index.
This allows us to create new properties that will be automatically set
during indexing, and cleared during re-indexing, just by choice of
property name.
By default, Sphinx tries to pre-process text through SmartyPants,
which attempts to convert ASCII quotes and dashes to Unicode
characters. Unfortunately, this mangles technical text such as command
lines. For instance, this excerpt from notmuch-tag.rst:
**notmuch** **tag** **--batch** [--input=<*filename*>]
got turned into:
notmuch tag –batch [–input=<filename>]
That's an en-dash and an em-dash respectively.
Not only are these characters visually confusing and could easily be
mistaken for a single dash, copying and pasting such command lines
into a terminal is doomed to result in incomprehensible error
messages.
* doc/conf.py: Disable SmartyPants.
A leading / in paths in a .gitignore file matches the beginning of the
path, meaning that for patterns without slashes, git will match files
only in the current directory as opposed to in any subdirectory.
Prefix relevant paths with / in .gitignore files, to prevent
accidentally ignoring files in subdirectories and possibly slightly
improve the performance of "git status".
gmime 3.0 no longer offers a means to set the path for gpg.
Users can set $PATH anyway if they want to pick a
differently-installed gpg (e.g. /usr/local/bin/gpg), so this isn't
much of a reduction in functionality.
The one main difference is for people who have tried to use "gpg2" to
make use of gpg 2.1, but that isn't usefully co-installable anyway.
the idea is that you can run
% notmuch search subject:/<your-favourite-regexp>/
% notmuch search from:/<your-favourite-regexp>/
or
% notmuch search subject:"your usual phrase search"
% notmuch search from:"usual phrase search"
This feature is only available with recent Xapian, specifically
support for field processors is needed.
It should work with bindings, since it extends the query parser.
This is easy to extend for other value slots, but currently the only
value slots are date, message_id, from, subject, and last_mod. Date is
already searchable; message_id is left for a followup commit.
This was originally written by Austin Clements, and ported to Xapian
field processors (from Austin's custom query parser) by yours truly.
In most part, our .rst documents are indented with 8 spaces instead
of tabs. Bring the rest of the lines to the same format.
Also, on one (supposedly empty) line, trailing spaces were removed.
If the --hello parameter is given, display the notmuch hello buffer
instead of the message composition buffer if no message composition
parameters are given.
Signed-off-by: Jani Nikula <jani@nikula.org>
Install man pages based on $(MAN_GZIP_FILES), which directly
corresponds to the man page source rst files. This way we can filter
the man pages to be installed as needed.
Use $(wildcard ...) to generate the list of man pages based on the rst
source files present in the man page directories, instead of reading
conf.py. This has three main benefits:
1) This makes the man page build slightly less complicated and easier
to understand. At least there are fewer moving parts.
2) This makes the build fail if we add a man page rst file, but fail
to add it to conf.py.
3) We can use Sphinx constructs in conf.py that are not available when
importing the file into a normal python program such as
mkdocdeps.py.
If Sphinx fails to create any of the roff files, having touch create
them hides the errors until someone realizes, possibly much later,
that the resulting files are empty. (Note that gzip doesn't fail on
empty input files.) Sphinx will change the timestamps of any files it
has written anyway.
Fix make sphinx-texinfo warnings:
WARNING: undefined label: notmuch-jump (if the link has no caption the
label must precede a section header)
WARNING: undefined label: notmuch-saved-searches (if the link has no
caption the label must precede a section header)
No need to repeat mostly the same information twice in conf.py. We
probably want to have a corresponding texinfo document for all the man
pages. Python list comprehension to the rescue. (The reverse is not
true; we have a texinfo document for notmuch-emacs we don't want as a
man page.)
There should be no user visible changes.
