I’d assume this problem has something to do with RSA. Just a guess. And It could maybe have something to do with the “ABC’s” of RSA. Who knows.
Lets click the links.
The first link we get is a link to a very refreshing ASMR video of a medieval battle.
After a few minutes of relaxing, I opened the second link.
Here we find a familiar set of numbers, an N, an E, and a C.
So since we have everything, this shouldn’t be that hard to decipher.
After a few minutes of online searching, I cam across a stack overflow post where one guy suggested using a tool called RsaCtfTool
Here is the link to it:
https://github.com/Ganapati/RsaCtfTool
After I cloned it to my desktop on kali linux, I opened up a terminal. I cd into the directory of the tool.
lets go back to the post to see how to format our command.
which explains to do it as python RSACtfTool – n {n} -e {e} –uncipher {c}
I replicate the command using the numbers we got from the challenge. Then I press enter.
Hmm, we got an error.
I figured I would try the command using python3 instead of python.
It worked! The tool ‘unciphered’ the cipher. (Down there at the bottom)
Flag: tjctf{BOLm1QMWi3c}
