Challenge - Image DNA
Santa has thousands of Christmas balls in stock. They all look the same, but he can still tell them apart. Can you see the difference?
Challenge - HV20.04 Br❤️celet
Santa was given a nice bracelet by one of his elves. Little does he know that the secret admirer has hidden a message in the pattern of the bracelet…
Challenge - Packed gifts
One of the elves has unfortunately added a password to the last presents delivery and we cannot open it. The elf has taken a few days off after all the stress of the last weeks and is not available. Can you open the package for us?
We found the following packages:
Challenge - Chinese Animals
The challenge description of day 2 read:
I've received this note from a friend, who is a Chinese CTF player:
恭喜！收旗爲：ＨＶ２０｛獭慬氭敬敧慮琭扵瑴敲晬礭汯癥猭杲慳猭浵搭桯牳ｅ｝
Unfortunately, Google Translate wasn’t of much help. I suspect the data has somehow been messed up while transmitting...
Happy HACKvent 2020
Welcome to this year’s HACKvent. Attached you can find the “Official” invitation to the HackVent. One of my very young Cyber Elves cut some parts of the card with his alpha scissors.
Have a great HACKvent,
– Santa
This is the teaser challenge, released a day before the start of this capture the flag event. We were presented the following text.
On the third day of christmas my true love sent to me…
three caesar salads,
two to (the) six basic arguments,
one quick response.
Sbopb 3 alkb! Lcc tfqe vlr! Db...In this article I derive a ray-sphere intersection algorithm from it's math. While certain knowledge in mathematics and programming will be assumed, I am trying to show all the steps of the process.
Ray-sphere intersection is used to determine wether and where a ray hits a sphere. This is useful in selecting 3D objects with the cursor (well, spheres in this case), calculating bullet hits in games, etc., but you knew that. Why else would you look up such a specific topic?
So let's start with what we have: a sphere (your object, a hitbox, ...) and a ray (a bullet, your cursor, ...). What we we'd like to know is, if they intersect and what the intersection point(s) are, if any.
For years I have used the "Open Calculator"-button on my keyboard as a hotkey to open KeePass. When I set up my new laptop, I wanted to configure KeePass to use my hotkey again – but it didn't work anymore.
Recently I had to implement encoder/decoders for some ISO standardized data structures in the area of intelligent transport systems. It's always nice having standards. Work went well until I encountered ISO 14823:2017. Up to this, for some strange reason, I considered ISO standards as infallible a...
In the course of the last week i moved some websites from my self managed VPS to an designated webhoster. Once moved, i encountered the problem that i could not use ngnix's proxy_pass feature. So i wrote myself a little ReverseProxy using PHP.
I wanted to move the websites from the VPS to an Web...