With F-Droid, we have been working towards getting a complete app distribution channel that is able to reproducibly build each Android app from source. while this may sound like a mundane detail, it does provide lots of tangible benefits. First, it means that anyone can verify that the app that they are using is 100% built from the source code, with nothing else added. That verifies that the app is indeed 100% free, open source software. [Read More]
Reducing metadata leakage from software updates
Update: now you can do this with Tor Onion Services Many software update systems use code signing to ensure that only the correct software is downloaded and installed, and to prevent the code from being altered. This is an effective way to prevent the code from being modified, and because of that, software update systems often use plain, unencrypted HTTP connections for downloading code updates. That means that the metadata of what packages a machine has installed is available in plain text for any network observer, from someone sitting on the same public WiFi as you, to state actors with full network observation capabilities. [Read More]
CipherKit updates: IOCipher and CacheWord
We’ve been on a big kick recently, updating the newest members of our CipherKit family of frameworks: IOCipher and CacheWord. There also are is a little news about the original CipherKit framework: SQLCipher-for-Android. IOCipher v0.2 IOCipher is a library for storing files in an encrypted virtual disk. It’s API is the exact same as java.io for working with files, and it does not need root access. That makes it the sibling of SQLCipher-for-Android, both are native Android APIs that wrap the SQLCipher database. [Read More]
Question: central server, federated, or p2p? Answer: all!
There are many ideas of core architectures for providing digital services, each with their own advantages and disadvantages. I break it down along the lines of central servers, federated servers, and peer-to-peer, serverless systems. a central service with clients connecting to it Most big internet companies operate in effect as a central server (even though they are implemented differently). There is only facebook.com, there are no other services that can inter-operate with facebook. [Read More]
New Official Guardian Project app repo for FDroid!
We now have an official FDroid app repository that is available via three separate methods, to guarantee access to a trusted distribution channel throughout the world! To start with, you must have FDroid installed. Right now, I recommend using the latest test release since it has support for Tor and .onion addresses (earlier versions should work for non-onion addresses): https://f-droid.org/repo/org.fdroid.fdroid_710.apk In order to add this repo to your FDroid config, you can either click directly on these links on your devices and FDroid will recognize them, or you can click on them on your desktop, and you will be presented with a QR Code to scan. [Read More]
Our first deterministic build: Lil’ Debi 0.4.7
We just released Lil’ Debi 0.4.7 into the Play Store and f-droid.org. It is not really different than the 0.4.6 release except in has a new, important property: the APK contents can be reproduced on other machines to the extent that the APK signature can be swapped between the official build and builds that other people have made from source, and this will still be installable. This is known as a “deterministic build” or “reproducible build”: the build process is deterministic, meaning it runs the same way each time, and that results in an APK that is reproducible by others using only the source code. [Read More]
Automatic, private distribution of our test builds
One thing we are very lucky to have is a good community of people willing to test out unfinished builds of our software. That is a very valuable contribution to the process of developing usable, secure apps. So we want to make this process as easy as possible while keeping it as secure and private as possible. To that end, we have set up an FDroid repository of apps generated from the test builds that our build server generates automatically every time we publish new code. [Read More]
Security in a thumb drive: the promise and pain of hardware security modules, take one!
Hardware Security Modules (aka Smartcards, chipcards, etc) provide a secure way to store and use cryptographic keys, while actually making the whole process a bit easier. In theory, one USB thumb drive like thing could manage all of the crypto keys you use in a way that makes them much harder to steal. That is the promise. The reality is that the world of Hardware Security Modules (HSMs) is a massive, scary minefield of endless technical gotchas, byzantine standards (PKCS#11! [Read More]
Tweaking HTTPS for Better Security
The HTTPS protocol is based on TLS and SSL, which are standard ways to negotiate encrypted connections. There is a lot of complexity in the protocols and lots of config options, but luckily most of the config options can be ignored since the defaults are fine. But there are some things worth tweaking to ensure that as many connections as possible are using reliable encryption ciphers while providing forward secrecy. A connection with forward secrecy provides protection to past transactions even if the server’s HTTPS private key/certificate is stolen or compromised. [Read More]
Turn Your Device Into an App Store
As we’ve touched upon in previous blog posts the Google Play model of application distribution has some disadvantages. Google does not make the Play store universally available, instead limiting availability to a subset of countries. Using the Play store to install apps necessitates both sharing personal information with Google and enabling Google to remotely remove apps from your device (colloquially referred to as having a ‘kill switch’). Using the Play store also requires a functional data connection (wifi or otherwise) to allow apps to be downloaded. [Read More]
Setting up your own app store with F-Droid
(_This blog post as now been cooked into an updated HOWTO_) The Google Play Store for Android is not available in all parts of the world, US law restricts its use in certain countries like Iran, and many countries block access to the Play Store, like China. Also, the Google Play Store tracks all user actions, reporting back to Google what apps have been installed and also run on the phone. [Read More]
Issues when distributing software
There is currently a discussion underway on the Debian-security list about adding TLS and Tor functionality to the official repositories (repos) of Debian packages that is highlighting how we need to update how we think about the risks when distributing software. Mostly, we are used to thinking about making sure that the software that the user is installing is the same exact software that has been posted for distribution. This is generally handled by signing the software package, then verifying that signature on the user’s machine. [Read More]