It's often difficult for me to say "no" to taking on new projects. Some ideas are so captivating that they beg to be implemented. The problem is, if you are eager to say "yes" to every interesting project that crosses your path, they'll quickly fill up your life to the exclusion of important things like spending time with family and friends.

Recently, I've started saying "no" to everything that gets proposed to me. I want to trim my obligations down to just a few things that I really care about. Once I do that, I'll be able to do a really good job of those few things, while still having time for all of the non-project things in my life. As well as not taking on any new projects, I've started to "end of life" some of the open source projects I've become responsible for over the years. These are the ones that are pretty much "finished" and no longer need to undergo active development:


defuse/php-encryption is one of the few cryptography libraries for PHP that doesn't get almost everything wrong. Version 2.0 is in the works, and it's nearly done. It adds support for encrypting large files without loading them all into memory, as well other things like composer support that make the library easier to use. It's probably about 40 hours of work away from completion. Once it's done, I don't expect to touch it ever again, except to fix bugs. If you need more features, you should be using libsodium (it has bindings for PHP).


defuse/password-hashing is password hashing code in PHP, C#, Java, and Ruby. It's the code that, for a long time, lived on's hashing security page. I'm ending its life since it uses PBKDF2 and today we have better options (bcrypt, scrypt, yescrypt, Argon2, etc.)

I'm happy to announce that just today I signed the git tag for its version 2.0 release. Version 2 has been nipping at my free time since 2014! Obviously, I'm relieved to finally have it finished. Version 2.0 makes all of the implementations compatible with each other, so that you can create hashes in PHP and check them in C#, or whichever combination you'd like. Having implementations that are compatible with each other, and tested against each other, also reduces the chance that any one of them has serious security bugs.

If you want to use PBKDF2 in a PHP, C#, Java, or Ruby project, it's definitely what you want to be using. But you should try to use the scrypt in libsodium first, and keep an eye out for the PHC winner Argon2.

I don't expect to touch the code any more, at least not until better algorithms are natively available in those languages. Maybe once PHP, C#, Java, and Ruby all natively support Argon2 I'll make a version 3.0, that's backwards-compatible with version 2.0, to make it easy for users to upgrade to the better algorithm.

The future?

So far I've told you I'm getting rid of the obligations in my life, and I've mentioned the two projects that I'm putting to rest. What will I be working on in the future?

I'm excited to announce that the University of Waterloo just offered me admission into an MMath computer science degree in quantum information. I couldn't be happier about it, because I've always loved physics, and getting to study physics alongside theoretical computer science sounds like it will be an amazing experience. I'm planning to meld the mathematics of quantum mechanics with my infosec background in interesting ways... hopefully some good will come of it.

So, my current priorities are:

  1. Zcash: This is my day job. I work with an awesome team of engineers to build what you might already know as Zerocoin or Zerocash. If anything on Earth is better than getting paid to learn physics and computer science, it's this job.

  2. The Underhanded Crypto Contest: This is a contest kind of like the Underhanded C contest, except for cryptography protocol designs and implementations. There's a 2016 contest, so if pretending to be the NSA and backdooring stuff is your thing, I encourage you to participate!

  3. Learning quantum information stuff before I go to Waterloo. I haven't accepted Waterloo's offer yet, but it's very appealing, and I want to go in already knowing a lot about quantum mechanics and the related computer science. So, hopefully I'll have some leftover time to do studying.

  4. Finishing my Flush+Reload research project. For my undergrad thesis I proved that you can use the Flush+Reload side-channel attack can tell which of a set of web pages you're visiting, or which of a set of PDF files you're opening, from another unprivileged user account on your system. I think this research is really important since it shows that Flush+Reload can do way more than just steal keys from OpenSSL. Right now the project has been passed on to another (very talented) student, so I'm hoping to have time to help them polish up the final results. Right now, there's a robust attack tool and good repeatable experiment code sitting in a private GitHub repository; I want to get that out for the world to play with as soon as possible.

  5. Yescrypt implementations: I'm implementing Solar Designer's yescrypt algorithm in a bunch of different languages. Sadly, this is my most neglected project, and I'm really disappointed with the feeble amount of time I've put into it. It's important, because it gives Solar Designer feedback on how easy it is to implement yescrypt and it double-checks the correctness of the reference code.

So, those are the 5 things I'm working on right now. Hopefully this list will keep getting shorter.