HSCTF 2020 Algorithms

Pythagorean Tree Fractal 1 Category: Algorithms Points: 100 Description: Please see the attached file for more details (and ignore the red dots on the images). Author: Plate_of_Sunshine Given: pdf named “Pythagorean_Tree_Fractal” Writeup This algorithm was pretty simple to make. After looking at the PDF given to us, we can see that our goal is to see how many rectangles there are at stage 50! Here is the math:...

June 6, 2020 · 2 min · Me

HSCTF 2020 Crypto

Chonky E Category: Crypto Points: 100 Description: E Note: P>Q Author: AC Given: ChonkyE.txt Writeup From the text file given, we see two different cryptosystems in play: RSA and Schmidt-Samoa. We are given the ciphertext encrypted by the Schmidt-Samoa cryptosystem and the n and e from the RSA cryptosystem. I have given links to the Wiki pages for both cryptosystems below. Schmidt Samoa encryption is very similar to RSA encryption....

June 6, 2020 · 4 min · Me

HSCTF 2020 Forensics

Picture Lab: Activity 10 Category: Forensics Points: 100 Description: Dear APCSA students, You thought you were done with Picture Lab. Unfortunately, you were wrong. We’re sorry. We should not have pushed this challenge out, it was irresponsible for us to deploy a meme challenge in the middle of a very serious “Catch-The-Flag” competition. We originally wrote this challenge as a joke, hoping that it would poke fun at Collegeboard’s APCSA “Picture Lab”; however, we now realize that this decision was insensitive and outright disrespectful to all those who have to solve the challenge....

June 6, 2020 · 3 min · Me

HSCTF 2020 Reversing

AP Lab: English Language Category: Reverse Points: 100 Description: The AP English Language activity will ask you to reverse a program about manipulating strings and arrays. Again, an output will be given where you have to reconstruct an input. Author: AC Given: EnglishLanguage.java & a pdf Writeup We can see right away that we have a .java file. I loaded up Eclipse and opened the .java file there....

June 6, 2020 · 6 min · Me

HSCTF 2020 Web

Blurry Eyes Category: Web Points: 100 Description: I can’t see :( https://blurry-eyes.web.hsctf.com Author: meow Writeup After clicking on the link, it takes us to a website with information on CTFs. We see that it says that our flag is … and is then blurred out. Best think to do is to Right-Click and “View page source”. Looking at the HTML, we don’t see anything useful besides the CSS class used for the flag....

June 6, 2020 · 4 min · Me