HSCTF 2020

I was given the following equations. Can you help me decode the flag?

Use flagCheck to input the flag you get from the challenge to get the actual flag

Author: HSN CS Club

Alice, Bob, and Carol are really close friends; in fact, they are so close, they even share the same primes in their RSA public keys! Alice has N = P*Q, Bob has N = QR, and Carol has N = PR, where P,Q,R are 1024 bit primes. All three also use the same public exponent e = 65537. Can you recover the three ciphertexts?

Use flagCheck to input the flag you get from the challenge to get the actual flag

Author: HSN CS Club

I found this file on my Keith's computer... what could be inside?

Use flagCheck to input the flag you get from the challenge to get the actual flag

Author: HSN CS Club

It seems that mountains are a great place for hiding secrets. Maybe you could find this one!

Use flagCheck to input the flag you get from the challenge to get the actual flag

Note: To view the image, open desktop mode and open the image via firefox

Author: HSN CS Club

My little brother who is in kindergarten was given this to him by his teacher. He wasn't able to solve it, but can you?

Note: 0 is black, 1 is white. The entire flag is hidden inside the word search, including flag{}. The flag may also be backwards or diagonally hidden.

Note: To view the image, open deskptop mode and open the file through firefox

Use flagCheck to input the flag you get from the challenge to get the actual flag

Author: AC

My friend gave this program to me, but I’m not sure what it means.

Note: Your output will have to be parsed into decimal representations of ASCII characters.

Use flagCheck to input the flag you get from the challenge to get the actual flag

Author: AC

Use flagCheck to input the flag you get from the challenge to get the actual flag

Author: HSN CS Club

This activity will ask you to reverse a basic program and solve an introductory reversing challenge. You will be given an output that is to be used in order to reconstruct the input, which is the flag.

Use flagCheck to input the flag you get from the challenge to get the actual flag

Author: AC

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.

Use flagCheck to input the flag you get from the challenge to get the actual flag

Author: AC