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So, today I have some news. I will be resigning as Ambassador for Hack The Box after our in-person meetup in June (2024). This means that I will be stepping down from organizing the monthly virtual and quarterly in-person Hack The Box meetups. Let me explain how I got to this decision.

The beginning

So, in 2019, I started out building a cyber security curriculum for NOVI Hogeschool. I had the ability to greenfield the courses and create something that is of value to students. In this curriculum I started using Hack The Box for exercises and training next to the regular classwork.

Last week I was a guest on the Cyber Cafe podcast by rootsec. It was a fun discussion on education and the current xz backdoor story. It is in the Dutch language. It is available on youtube and included below:

This post is just a small note for those of you who also run Microsoft Teams on Linux through their browser and now receive a note “your browser does not meet the requirements for the new Teams”. It turns out that the client is looking at the user-agent string to determine which browsers it accepts, and which not.

So, if you have the message, install an user-agent switcher and select a common browser on a common OS (from the MS perspective) and you will suddenly meet the requirements.

This is a longer form article. I is relevant as of February 18th 2023. If the circumstances of my environment changes I will try to update this article to reflect the situation. You can find the full source code of my dotfiles on Github.

I like consistency and simplicity. I do not like to use many different tools to do different things, I rather spend my time learning to use a few tools very well then to follow the hype on the latest trend of tools for something we have been doing forever.

It has been a little while. I have been swamped with work and the work on my thesis, leaving no room to finish the Advent of Code or much of anything else.

Yesterday I gave my practice presentation for my thesis. This means I am one more step closer to the finish line. During the day there were many interactions with fellow students. One of the topics has been the templates to use at Open Universiteit. So, I thought I would just create a repository of the templates that I use, so that anyone can learn from them.

The weekend generally is a place to find hard puzzles again, this time not so much. A simple quest to find the next number in a sequence with a fully written out algorithm to follow. They key here is to use recursion.

Somewhat suspicious of 2 easy days we end up at Day 8. A simple map to follow again, from one key follow the instructions until we hit ZZZ. Part 2 had us do it for several keys at once, with the goal to find the spot where they all converge. This can take forever, erhm, a long time.

So there has to be a math type solution to this problem. It turns out to be a Least Common Multiple problem. It is the smallest positive integer that is divisible by two or more numbers without leaving a remainder. To find the LCM of two or more numbers, you can use a method called prime factorization or a simpler approach involving multiples. We can also use the Greatest Common Divisor (GCD) to find the LCM.

Today we learned about CamelCards, a game of poker meant to play on the back of a camel. The most interesting part here was the parsing of the cards and figuring out how to properly rank them. Part 2 turned out to be as easy as tracking Jokers.

Day 6 turned out to be the easiest day in the range so far. A simple implementation of the algorithm was more than sufficient.

I later learned that it was a quadratic function. On the subreddit Deatranger999 said:

If you hold down the button for x seconds, then you will beat the distance if the quadratic x^2 - t x + d is at most 0, where t is the total time of the race and d is the distance you’d like to beat. So I just plugged each one into WolframAlpha, found the roots, and then calculated the number of integers between the two roots.

Today was an interesting problem. We are basically given a map to follow based on a number, possibly transforming the number at each step. With a single number this is quite simple, just apply the rules and step through each set of transformations. The problem becomes tricky when it turns out we have to deal with enormous ranges of numbers. On the subreddit some people reported their implementation to take hours and use 20GB of memory.

The difficulty is going up and down. This day was quite easy in comparison to yesterday. Today it was about parsing some numbers and finding a set of winning numbers.

As I am doing these puzzles in Go I found out that there is no default set type. There is an implementation by HashiCorp named go-set that fills this void. I did not use an external package (I try to avoid them while doing AoC), but I am very tempted to pull that package in.

Day 3 was quite something. I think that in an attempt to make it harder for AI to solve the puzzles the creators also increased the difficulty level of the base puzzles a little too much. The test was not very clear as to what should happen with negative numbers and it might trip people up. The puzzle itself is a great to exercise grid knowledge as you have to work with neighbors and you have to extend the numbers when you find them. Part 2 was just some bookkeeping on my existing implementation, so it was not too much work.

Day 2 was another fun challenge. Lots of splitting of strings. I wonder if there is a better way to filter out the min and max value from the separate grabs.

I am sure I will not be able to complete all challenges this year, but so far so good.

The Advent of Code has started again. At NOVI we participate with a group of our students. We use the AoC throughout the entire curriculum as practice exercises to learn new programming languages or the application of data-structures and algorithms.

Day 1 was a tricky start for most people. Part 1 was not too bad, but part 2 tripped most people up. I guess the idea was that you would have to solve the challenge with an array iteration, but most students tripped up. They tried to match each word and replace the occurrence in the text, running head-on into the edge-case where 2 numbers overlap, such as “eightwo”.

As the warm haze of summer gives way to the crisp air of autumn, the season marks a pivotal moment in my academic journey: the commencement of my Master’s thesis project. Having successfully had my research proposal accepted earlier this year, I now face the last leg of this marathon—bringing my theoretical framework to life.

The Powerhouse Partnership: Open Universiteit and CWI

While undertaking a Master’s thesis is a significant endeavor on its own, I always have to make it more complex. My research will be a collaborative effort between two prominent institutions: the Open Universiteit and the Centrum Wiskunde & Informatica (CWI).

Working on my thesis research proposal has been quite the journey, and not always in the direction I would have chosen. A personal revelation that struck me during the process is the tight and rather vexing relationship between perfectionism, procrastination, and paralysis.

It’s often said that the perfect is the enemy of the good. In my quest for the ‘just right’ words to articulate my thoughts, I found this saying to be glaringly accurate. The ticking clock became a dull backdrop to my cerebral scavenger hunt. My concentration started to drift and instead of zeroing in on my research proposal, I found myself fixated on, of all things, the color scheme of my desktop environment.

Using AI, in particular generative models such as GPT, are in contention within academics. The purity of academics resides in students writing on their research and having their work peer-reviewed. But how can you now be sure that the student wrote the paper and how can you trust its content? Many universities, including the OU have written about it. The OU published an article in Modulair about it. Generally, the consensus seems to be that it is ok to use AI as an assistant, but you must write your texts.

Today, I took the first step towards starting my master’s thesis. I have decided to document my journey and experiences on my blog. Given that the thesis will play a pivotal role in my life for the next nine months, I expect it to be a thrilling journey.

Finding a topic

As a student at Open Universiteit in The Netherlands, I had the opportunity to work with the Rascal programming language during the Software Quality Management course. I found the language intriguing and enjoyed working with it throughout the module. After consulting with my professor, we brainstormed various possibilities for my master’s thesis topic, ultimately settling on the creation of a visualization library for the language.

Background

I have been working on getting my Master’s degree in Software Engineering. To do this I have started following courses at the Dutch Open Universiteit. They have a Master’s program that takes 2 years and you are able to follow it from home.

Original Post

During each in-person Hack The Box meetup I have a small badge challenge that will give the first solver of the challenge a price. at the meetup of March 2023 there will be a very nice little challenge to be done as well, a beautiful NOVI hoodie. You can already download the password protected zip archive. The password will be shared during the meetup opening words.