Vous l’avez peut-être vu passer, cette semaine j’ai doublé mon salaire du mois de septembre grâce à un concours d’algo.

In this article, I want to illustrate three levels of solving a crackme problem. The challenge is called Easy Crack Me, from TokyoWesterns CTF 2019. I really enjoyed playing this CTF which was very hard as expected (even the “easy” problems), but I managed to briefly make it to the top 100 even though I was playing alone.

Here’s a simple dataviz I made while trying to understand the community behind our Twitter account @h25io. I especially wanted to see where the audience comes from, and how strongly it overlaps with the company’s founders @MathisHammel and @clement_hammel.

This is my solution to a cool problem I found while playing the Facebook Hacker Cup recently.

For the 4th year in a row, I’ve registered for the Facebook Hacker Cup, a great coding competition played in 4 rounds and a final, where my personal goal is to make it to the world’s top 500 to earn a T-shirt. Last year I ended at the 282nd place out of 8200 which wasn’t enough to advance to the last round, but I got the T-shirt ! If I win the same Hacker Cup T-shirt this time, I’ll give it away to one of my Twitter followers who retweets one of my Hacker Cup articles.

It’s been 6 months I haven’t been playing CTFs, mostly due to me graduating INSA and having to leave its academic team InSecurity. But I’m back in the game, so let’s celebrate by breaking some crypto !

This weekend, I played SpamAndFlags CTF Teaser 2019, which was a very interesting CTF. I didn’t play for too long, having another CTF and the Google Code Jam quals at the same time, but there was a particular task that I immediately fell in love with : the goal was to find a counter-example to Fermat’s last theorem in order to get a flag.

Almost a year ago I started using an app called “Too Good To Go” (this article is not sponsored!). Its goal is to reduce food waste by allowing stores from all around Europe to sell their unsold products to the app users at a very small price. You usually pay 20 to 50% of the retail price, but the products have very short expiration dates and you don’t know what you will get beforehand.

I recently launched a small Code golf contest on the Advent of Code 2018 day 20 problem. Contestants had to submit their shortest source code which gives a correct answer, and I received 17 submissions over the four days of the contest.

Il y a quelques semaines, j’avais publié une solution de l’exercice 5 du BattleDev de novembre 2018.

Here are my solutions to the Advent of Code 2018, updated almost daily with new challenges.

Il y a quelques semaines s’est tenue la 12ème Battle Dev. J’ai décroché la 100e place tout pile, et bien que déçu par mon classement je trouve que les problèmes étaient de très bonne qualité, en particulier les deux plus difficiles dont je vais présenter la solution ici.

I’ve been busy recently and couldn’t play CTFs as much as I used to, but IceCTF was such a good memory in 2016 that I really wanted to play their second edition !