C#

HACKVent 2020 – Day 12

Challenge – Wiener waltz

During their yearly season opening party our super-smart elves developed an improved usage of the well known RSA crypto algorithm. Under the “Green IT” initiative they decided to save computing horsepower (or rather reindeer power?) on their side.…

HACKVent 2020 – Day 11

Challenge – Chris’mas carol

Since yesterday’s challenge seems to have been a bit on the hard side, we’re adding a small musical innuendo to relax.

My friend Chris from Florida sent me this score. Enjoy! Is this what you call postmodern?…

HACKVent 2020 – Day 7

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Challenge – Bad morals

One of the elves recently took a programming 101 course. Trying to be helpful, he implemented a program for Santa to generate all the flags for him for this year’s HACKvent 2020. The problem is, he can’t remember how to use the program any more and the link to the documentation just says 404 Not found.…

HACKVent 2020 – Day 6

Challenge – Twelve steps of christmas

On the sixth day of Christmas my true love sent to me…

six valid QRs,
five potential scrambles,
four orientation bottom and right,
and the rest has been said previously.


PDF version

Requirements

a printer

Hints

selbmarcs

Solution

Since I am not that much into rubik cubes, I tried the brute force method.…

HACKVent 2020 – Day 5

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?

Solution

The first attempt so solving the challenge was to load the images into an editor and inspect them visually.…

HACKVent 2020 – Day 3

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.…

HACKVent 2020 – Day 2

Challenge – Chinese Animals

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 it.

Sadly, I can’t ask my friend about more details.

HACKvent 2020 – Day 1

Challenge – 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

Solution

Those alpha scissors are clearly a hint.…