Devel March 2018

devel@lists.sequoia-pgp.org

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2 discussions

Decryption support in the tool & Python bindings
by Justus Winter 27 Mar '18

27 Mar '18

Hi :) I went ahead and implemented support for decrypting symmetrically encrypted messages in our 'sq' tool, mostly to get a feeling for how the parser works: % echo 123456789 | sq decrypt -i openpgp/tests/data/messages/encrypted-aes128-password-123456789.gpg 2>/dev/null | head -n 8 A Cypherpunk's Manifesto by Eric Hughes Privacy is necessary for an open society in the electronic age. Privacy is not secrecy. A private matter is something one doesn't want the whole world to know, but a secret matter is something one doesn't want anybody to know. Privacy is the power to selectively reveal oneself to the world. For the curious, here [0] is the code. Note that this code is using the low-level API, we don't expect that every application developer will use this, but 0/ some people might, and b/ currently there is no high-level API. 0: https://gitlab.com/sequoia-pgp/sequoia/commit/30604553c08564e27621ce1e022cf… Then I was curious how the parser API would translate to the foreign function interface, so I added just barely enough glue to be able to do the same from C or Python. The Python version looks like this: import sys import os from getpass import getpass from enum import Enum, auto from sequoia.core import Context, NetworkPolicy from sequoia.openpgp import Tag, PacketParser ctx = Context("org.sequoia-pgp.tests", network_policy=NetworkPolicy.Offline, ephemeral=True) class State(Enum): Start = auto() Decrypted = auto() Deciphered = auto() Done = auto() state = State.Start algo, key = None, None pp = PacketParser.open(ctx, sys.argv[1]) while pp.has_packet: packet = pp.packet tag = packet.tag if state == State.Start: if tag == Tag.SKESK: passphrase = getpass("Enter passphrase to decrypt message: ") algo, key = packet.match().decrypt(passphrase.encode()) state = State.Decrypted elif tag == Tag.PKESK: sys.stderr.write("Decryption using PKESK not yet supported.\n") elif state == State.Decrypted: if tag == Tag.SEIP: pp.decrypt(algo, key) state = State.Deciphered elif state == State.Deciphered: if tag == Tag.Literal: body = pp.buffer_unread_content() os.write(sys.stdout.fileno(), body) state = State.Done pp.recurse() assert state == State.Done It is structured like the Rust version and I think it looks quite reasonable. (To use it, grab the latest Python branch from [1]). 1: https://gitlab.com/sequoia-pgp/sequoia/tree/justus/python-4 Cheers, Justus

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Playing with the Python bindings
by Justus Winter 16 Mar '18

16 Mar '18

Hello :) I have been working on the foreign function interface, aka our C API. Instead of writing tests for that, I decided to write bindings for Python and testing that. This also gives me a feel for how complete and usable the C API is. And while there is no documentation yet, I have integrated it in our new build system and I invite you to try it out. Even if you are not into Python, it is a nice way to interactively play with Sequoia. To get it, either checkout the 'justus/python-3' branch or clone it using: % git clone -b justus/python-3 https://gitlab.com/sequoia-pgp/sequoia.git In addition to the build dependencies mentioned in 'README.md', you need python3-dev, python3-cffi (poke me if I missed any additional dependencies) and ipython3 (only for the nice interactive shell). Then do 'make', followed by: % make -Cffi/lang/python shell [... stuff...] IPython 5.5.0 -- An enhanced Interactive Python. ? -> Introduction and overview of IPython's features. %quickref -> Quick reference. help -> Python's own help system. object? -> Details about 'object', use 'object??' for extra details. In [1]: Wow, an interactive Python shell with all of Sequoias functionality already imported for you and a Context 'ctx' already created for your convenience is at your fingertips. Let's have some fun: In [1]: fp = Fingerprint.from_hex("D2F2C5D45BE9FDE6A4EE0AAF31855247603831FD") In [2]: keyid = fp.keyid() In [3]: tpk = KeyServer.sks_pool(ctx).get(keyid) In [4]: assert fp == tpk.fingerprint() In [5]: st = Store.open(ctx, "my awesome store") In [6]: st.import_("Justus' signing key", tpk) Out[6]: <sequoia.openpgp.TPK at 0x7fc5c0142780> In [7]: binding = st.lookup("Justus' signing key") In [8]: list(map(str, binding.log())) Out[8]: ["2018-03-16 13:10:10+00:00: org.sequoia-pgp.tests.interactive:my awesome store: New binding Justus' signing key -> 3185 5247 6038 31FD"] For more ideas you can look into ffi/lang/python/tests. Cheers, Justus

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Devel March 2018