GnuPG News for Summer 2015

It's been a few months since the last posting. Our most visible activity has been several presentations, but hacking has continued.

In July, Neal attended RMLL in Beauvais, France and presented "An Advanced Introduction to GnuPG". This presentation is for anyone who knows how to encrypt, decrypt and sign data, but wants to learn how messages are constructed, better understand GnuPG's architecture, and hear some tips and tricks for making the most of GnuPG. The presentation went quite well: the room was nearly full and there were a number of questions at the end as well as after the talk.

In August, Werner, Niibe and Daniel Kahn Gillmor (dkg) attended Debconf in Heidelberg. Werner held a keynote: "GnuPG: Past, Present and Future." The presentation was recorded and the slides are also available. Werner started with the history of GnuPG. He related some anecdotes about his motivation to start the project, some of the legal challenges (working around patents), and the founding and running of g10 Code, the free software company behind GnuPG. He then talked about current activities both within GnuPG (some new features and the recent fund raising campaign) as well as some activities related to GnuPG (in particular, the rechartering of the OpenPGP working group). Finally, he discussed his vision for the future. In particular, he wants GnuPG to be easier to use for the masses. This means, for instance, using TOFU as a trust model instead of the web of trust, which requires too much curating for nearly all users—including most technical users—to be effective. Nevertheless, the goal isn't to somehow neuter GnuPG: it will remain possible to harden GnuPG for users who are trying to prevent targeted attacks with just a few configuration options. The primary focus, however, is making GnuPG easier to use and more secure for casual use by default.

Also at DebConf, dkg presented "GnuPG in Debian Report" on behalf of the GnuPG packaging team (slides). He reported the status of GnuPG in Debian and what the team has planned. He began by relating the current status of GnuPG in Debian. First, everything has been moved over to git. The packaging team has also adopted not only GnuPG, but several related packages. The team has been uploading version 2.1 to experimental and, shortly before the talk, made the first upload to unstable. A lot of work has been done on minimizing GnuPG's dependencies. This is particularly helpful for server installs that don't need any of the graphical components. Unfortunately, this work didn't make it into Jessie, but the workaround is easy (install pinentry-curses before installing gnupg2). The plan is to support GnuPG 2.1 by default. As such, it will be installed as /usr/bin/gpg (not /usr/bin/gpg2). Note: GnuPG 1.4, with its support for old, broken crypto will remain available for those few who still need it, but it will no longer be the default in the next version of Debian. Making GnuPG 2.1 the default also means that support for ECC cryptography will become much more widely spread in the near future. Daniel also called for support for encrypted swap by default and encouraged people to file bugs. He then turned to some divergences from upstream. He wants GnuPG to be stronger by default and he wants to do some Linux-specific hardening. Some possible future work are: integrating autopkgtest, for testing the built package in specific environments; and, improving desktop integration and the UI/UX. dkg also mentioned that he is excited about the proposed official support for TOFU in GnuPG: he has a set of scripts for implementing TOFU and would like better support. dkg also ran a GnuPG Packaging BoF, which was recorded as well.

Niibe is running a campaign called "more entropy, please." His goal is firstly to raise awareness of the importance of entropy and also about making computations constant time to avoid side-channel attacks. He presented this campaign at DebConf. His presentation was recorded and he wrote a followup article.

This campaign is related to Niibe's works on a true random number generator (TRNG) and smartcard called NeuG. This device runs only free software and the schematics are also freely available. The device is available for purchase from the FSF's shop. Happily, it is so popular that it sold out (but more are on the way!).

At the end of August, Werner attended the "Sommerakademie 2015: Ohne Vertrauenswürdigkeit keine Informationsgesellschaft," which was organized by the Unabhängiges Landeszentrum für Datenschutz Schleswig-Holstein. He held a keynote in which he introduced public-key encryption and GnuPG to privacy activists. In addition to the slides, he also wrote a short handout. Note: both are in German. Werner held the same talk at the Düsseldorf Fellowship meeting.

At the beginning of November, Werner will hold a keynote at FSCONS in Göteborg, Sweden.

Due to renewed interest in the OpenPGP protocol, the IETF OpenPGP working group was rechartered in June to work on updating the OpenPGP specification. The group is co-chaired by dkg. Both he and Werner attended the IETF-93 OpenPGP session (Werner attended remotely) to discuss its agenda. The minutes are also available.

Neal recently spearheaded an effort to better integrate GnuPG and Gnome Keyring. For a long time, Gnome Keyring proxied access to gpg-agent. Unfortunately, the proxy was incomplete and this proved to be a serious problem with GnuPG 2.1. Since Gnome Keyring only wanted to provide a passphrase cache, we decided to modify gpg-agent to support this directly. This work has been completed in GnuPG and the proxy has since been removed from Gnome Keyring. Stef Walter recently announced this to Gnome's distributor list so we should see a proper fix to this long-standing issue coming to end users soon.

Neal posted a design document about integrating TOFU (trust on first use), a new trust model, into GnuPG. As noted above, TOFU requires little support from users. The Web of Trust, on the other hand, requires not only signing keys, but for every user to assign trust to people they potentially don't know. This is a huge burden and few people actually do this in practice. As such, they are getting less protection than with TOFU, which is able to detect when a user's key changes. Note: our intention is to support both TOFU and the Web of Trust at the same time.

We have modified Pinentry to use normal widgets instead of the custom widgets that use locked memory. Rough consensus for this decision was reached on the gnupg-devel mailing list. The motivation is that the secure widget code is large and buggy and it relies on lots of code to carefully handle the password (namely, anything that deals with keyboard input, such as, the X server, the graphical toolkit and the C library). This supporting code is not designed to be secure and thus probably isn't. Further, in practice, locked memory isn't really locked anymore. It can still be written to disk if the machine is hibernated. Finally, the secure widgets are less feature rich and don't integrate as well into the desktop environments. This is particularly important as regards accessibility. Neal modified the gtk-based pinentry and Andre modified the Qt-based pinentry to use the standard widgets. This allowed us to immediately close a number of bug reports.

Niibe has been working on integrating support for Curve25519 for encryption. This is available in the latest version of libgcrypt and scdaemon.

Kai has been working on various enhancements for Enigmail. In particular, Enigmail now displays the algorithms used for signing messages under "Enigmail Security Info". He added functionality for importing and exporting Enigmail preferences. Enigmail now asks before importing public keys from attachments. And, a patch is pending that allows Enigmail to use as keyserver.

There have been a number of new releases. These include: GnuPG 2.1.8, GnuPG 2.0.29, GPA 0.9.9, libgcrypt 1.6.4, libassuan 2.3.0, libgpg-error 1.20, GPGME 1.6.0, and Pinentry 0.9.6. Andre Heinecke also released gpg4win 2.2.6.

On GnuPG-devel, Bjarni reraised the memory-hole discussion. This was originally discussed at the OpenPGP summit back in April. The idea is to be able to sign and encrypt sensitive mail headers, such as the subject. Both Mailpile and Enigmail already have partial support for the proposed standard.

Jan Suhr asked about GnuPG using exclusive mode when accessing OpenPGP cards. Niibe and Werner argued that only a single application should use the smartcard at a time. There are two main arguments: performance and security. From a performance perspective, GnuPG (or rather, scadaemon) can cache the status of the card. Having to refresh information (and rerun the initialization procedure) can introduce a several second delay. From a security perspective, we want to make sure that another application does not get access to the card without having to enter the PIN.

On gnupg-users, Simon Josefsson asked about how to setup a shared email with hardware-backed keys. He detailed his setup and dkg thought it was sound and also mentioned an alternative approach.

A.T. Leibson started an interesting thread on teaching GnuPG to new users. A number of people replied with suggestions and anecdotes. If you are an encryption advocate, it is probably worth a look.

Tankred Hase linked to the Secure Private Key Synchronization protocol, a secure way to synchronize a user's private key between devices. This was originally discussed at the OpenPGP summit. He's interested in additional feedback.

Nico posted a design document for a key server that validates OpenPGP keys by sending a mail to the key's holder. A main issue that was raised was how to decide which key server should be authoritative: users are not going to want to validate that they control the key to hundreds of key servers. Werner noted that this effectively reimplements X.509 and its trusted CAs.

Nico asked for feedback on how to organize the next OpenPGP summit. He wants to have a meeting that is open to the public, but with some limitations to ensure that work gets done and that the limited space is available to those most engaged in OpenPGP.

Robert J. Hansen has begun overhauling the FAQ. He is planning on removing references to GnuPG 1.4 as much as possible. He also sought feedback about some proposed clarifications.

About this news posting

We try to write a news posting each month. However, other work may have a higher priority (e.g. security fixes) and thus there is no promise for a fixed publication date. If you have an interesting topic for a news posting, please send it to us. A regular summary of the mailing list discussions would make a nice column on this news.