Find the message is a crypto challenge that was part of the MetaRed CTF 2022 (4th STAGE).

Sy@t{N_f0yq13e fubBg$, n uNpx3E t!irf 3agrE}

We were give no other information.

First look

To solve this challenge, we need to find the encryption method used.

The website pointed us to the Vigenere cipher.


Now we had to find the key.

Using the same website, with the Knowing a plaintext word option, and word FLAG as a first guess, got us these results:

YLAJBV	Un@t{E_e0ds13t flaGi$, c uEoc3G i!iie 3figE}
NNTHC	Fl@a{G_d0ld13l ysoOn$, g sAce3X r!vem 3teeR}
ENNNKM	Ol@g{A_v0mm13r shrPc$, a hAfl3A g!vev 3oceR}
YLDGFU	Un@q{H_a0es13t cowHi$, c rHkd3G i!fla 3gigB}
AJBV	Sp@s{S_f0pp13j flaGg$, e tSpo3D y!iie 3fgiD}
TTCNNS	Zf@r{A_s0gx13l dhoJn$, u sAcf3L a!ges 3inyC}
NNTHNQ	Fl@a{G_s0id13r mnoLt$, a bGch3R g!pks 3kteL}

Turns out that FLAG is not in the message. But we weren’t that far off. NNTHNQ seems to be very close.

The first and second letter of our plaintext should be F and L (from FLAG{...) and the first two letters of NNTHNQ are N which gave us Fl@a{G_s0id13r mn....

So we tried the Knowing the Key/Password option with N:

Fl@g{A_s0ld13r shoOt$, a hAck3R g!ves 3nteR}

That’s it!


The flag is “Fl@g{A_s0ld13r shoOt$, a hAck3R g!ves 3nteR}”.