david wong

Hey! I'm David, the author of the Real-World Cryptography book. I'm a crypto engineer at O(1) Labs on the Mina cryptocurrency, previously I was the security lead for Diem (formerly Libra) at Novi (Facebook), and a security consultant for the Cryptography Services of NCC Group. This is my blog about cryptography and security and other related topics that I find interesting.

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Réseaux posted November 2013

I have an exam of Réseaux (Network) tomorrow and the slides of my prof are... how could I say this... not really clear. We have practical applications classes but they were... organized in the worst possible way. The subject did seem interesting at first but I felt like I learned nothing. Hopefully for the past few weeks I've been using the wonderful online course An Introduction to Computer Networks given by Nick McKeown and Philip Levis both very competent profs from Stanford. It seems like I should have gone there for my master of Cryptography :) Anyway, I'm doing with what I have here and I feel blessed studying Cryptography right when free online courses started becoming a thing.

The course is available here.

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Bullrun posted November 2013

Bullrun or BULLRUN is a clandestine, highly classified decryption program run by the United States National Security Agency (NSA). The British signals intelligence agency Government Communications Headquarters (GCHQ) has a similar program codenamed Edgehill. According to the NSA's BULLRUN Classification Guide, which was published by The Guardian, BULLRUN is not a Sensitive Compartmented Information (SCI) control system or compartment, but the codeword has to be shown in the classification line, after all other classification and dissemination markings. Information about the program's existence was leaked in 2013 by Edward Snowden.

from https://en.wikipedia.org/wiki/Bullrun_%28decryption_program%29" target="_blank">wikipedia.

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Sudoku Solver posted November 2013

My Programmmation class first part is about coding a sudoku solver. We have to do everything in english, we have to commit with svn, we have to write a final report with LaTeX.

Every week we're given some vague guidelines and we have to dive deep into C to first, understand what we have to do, and secondly, find solutions in a language we've never really played with before. We have to turn in what we did every week, if our code doesn't compile it's a zero, if it does compile it goes through a multitude of tests that quickly decrease your grade (out of 20). Let's just say I spent many nights and early mornings coding and I started the first week with a 2/20.

It felt like a crash course, it felt unfair at times, but holy cow did I learn some C in a really short amount of time. Props to my professor for that, and I wish I had more courses like that. I might not get the best grade out of this course but I sure learn the most things there.

I've also committed everything I've done on a public git repo so everyone can see how it looks like here :

https://github.com/mimoo/sudoku

You can compile with make, learn how to use with ./sudoku -h

It can read sudokus of different sizes from 1x1 to 64x64 as long as it is presented like this :

#this is a comment

5 3 _ _ 7 _ _ _ _

6 _ _ 1 9 5 _ _ _

_ 9 8 _ _ _ _ 6 _

8 _ _ _ 6 _ _ _ 3

4 _ _ 8 _ 3 _ _ 1

7 _ _ _ 2 _ _ _ 6

_ 6 _ _ _ _ 2 8 _

_ _ _ 4 1 9 _ _ 5

_ _ _ _ 8 _ _ 7 9
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One more list posted November 2013

It's time for a new list of random things I noticed about Bordeaux :

  • Many 2€ kebab places. Also, kebab here are made with a Lebanese bread, like a crepe, and not with the half of an Arabic bread like in Lyon.
  • It's raining, A LOT. It's raining at least once a week, but usually way more than once a week.
  • It's not that cold. I just came back from a week in Lyon and oh my god was it cold there, you can feel winter coming, but in Bordeaux ? Chill, you don't need that jacket.
  • There are no Bordelais. Most people I run into come from other places in France. I actually only met one Bordelaise and it was during my first week here.
  • The city is really not that big. In 30 minutes you feel like you've seen most of it.
  • We have Velov' in Lyon, Velib' in Paris, here it's Vcub. Those free bikes you can rent pretty much anywhere.
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What is it like in Bordeaux? posted October 2013

So, I've been living here for a month and here is my list of what it is to live in Bordeaux.

  • People say "chocolatine" instead of "pain au chocolat" and "poche" instead of "sac". It's kind of weird, especially when I have to say it, I'm always scared that they can tell I'm not from here, which is a stupid thing to be scared of, I had the same kind of feeling when I was living in Canada or China and didn't have the same accent as the locals, but it's weirder having that feeling in my own country.
  • Streets are dirty, really dirty, you will always have to avoid dog poops when you go somewhere. Sidewalks are very small so you also always have to walk directly on the road.
  • The city is pretty small. It's easy to get around. But when something is a bit far, it's annoying to get there since there is no subway.
  • The public transportation system is horrendous, every morning I have to get squished by a thousand students taking the same tramway, most of the time I miss several trams because there are too many people inside, my personal record is seeing five tram passing without being able to enter them. Pretty annoying.
  • Not so much accent here, but people say "gavé" a lot, it means "very". For example "c'était gavé bien hier soir".
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