Crypto: 23 times

Challenge Description

What could this message (attachment) possibly mean?

“Veni, vidi, vici” - Some guy, a few years back

Attachment

OFPZ{uvw_fp_qeb_kbt_xyz}

Approach

I’m sure a decent chunk of people reading this would immediately recognise the above as being a ROT cipher. If you didn’t, that’s okay - there’s a good way to determine that it is in fact a ROT cipher!

We know from previous challenges (and the attendance flag) that all of the flags start with RISC{ - and the attachment seems to follow that structure too. If we wanted to precisely determine that it is a ROT cipher instead of some other substitution cipher, we can observe letter distance:

R -> O      -3 letters (nOpqRs)
I -> F      -3 letters (eFghIj)
S -> P      -3 letters (oPqrSt)
C -> Z      -3 letters (yZabCd)

Every letter appears to be -3 from what we expect the flag to start with.

Besides this observation, there’s other hints:

• “23 times” - Julius Caesar was stabbed 23 times
• “Veni, Vidi, Vici” - Caesar quote

Going to CyberChef, we can see that with a rotation of 3, we get our desired flag:

RISC{xyz_is_the_new_abc}