Introduction
A cybersecurity competition for high schoolers.
I participated with the team IrisCS and scored 1875 points landing us in 181st Place. We completed several challenges.
Below are the challenges I completed.
Keysar
Information: 905 Solves, 40 Points.
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Hey! My friend sent me a message... He said encrypted it with the key ANGSTROMCTF.
He mumbled what cipher he used, but I think I have a clue.
Gotta go though, I have history homework!!
agqr{yue_stdcgciup_padas}
Author: joshdabosh
The referenced cipher is a keyed ceaser cipher. In order to decode it, I will use Rumpkin’s decoder.
Link: http://rumkin.com/tools/cipher/caesar-keyed.php
After plugging in the given key and cipher text, I was given the flag.
Flag:
actf{yum_delicious_salad}
Consolation
Information: 50 Points, 580 Solves
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I've been feeling down lately... Cheer me up!
Refer to the youtube video below for an explanation and flag. The solution involves the chrome debugging console.
WS1
Information: 30 Points, 1222 Solves
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30 Points | 1222 Solves
Find my password from this recording (:
See the video below for an explanation. Basically, see all the wireshark streams and you will find a url-encoded flag.
PSK
266 Solves - 90 Points
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My friend sent me yet another mysterious recording...
He told me he was inspired by PicoCTF 2019 and made his own transmissions. I've looked at it, and it seems to be really compact and efficient.
Only 31 bps!!
See if you can decode what he sent to me. It's in actf{} format
Author: JoshDaBosh
See the video below for an explanation.
Basically, the audio file given is in the format BPSK31. In the video, I go over using a certain program to decrypt it.
Conclusion
This was a solid CTF. My team was excited to play in this CTF as it was popular and well recieved last year. It did not dissapoint.