Steganography - TENET

"Two realities coexist: one moving forward, the other in reverse. Your past self has left you clues, but only by decrypting both timelines can you escape. Can you break free before the loop resets?"

Note: Be Cautious with Flag Format of this challenge

Solution :

There was a file.wav and a time.jpeg attached with this challenge. Opening .wav file in sonic visualizer gave me a image with a string imprinted in it, so mirrored and made it right to get this string "tenet_opera_rotas"

Next step, I tried steghide for the time.jpeg steghide extract -sf time.jpeg . For the password, tried out various different combinations and extracted a latin.txt file with pass "sator_arepo_tenet" (TENET reversed is TENET, palindrome W).

Latin.txt

U2FsdGVkX1/7+V1o59yZ8g3TFdiYlCkbIgYMPx4qIV8ECViq1CNiveKje89pltcN 0+JIHaE5YZcbn9UjV+wFfw==

I was later given a hint for this challenge, it says - "Use 256 to unlock, 512 to guide the way."

Therefore, by looking at the hint I found out we have to decrypt it using aes-256 and sha512: so, decrypted it with the same password i got from the .wav file "tenet_opera_rotas" (got it after trying various combinations from the sator square).

Command to decrypt

openssl enc -d -aes-256-cbc -base64 -pbkdf2 -md sha512 -in latin.txt -out output.txt -pass pass:"tenet_opera_rotas"

The output.txt had the flag.

Flag: VishwaCtf{7H3_FUTUR3_HAS_ALR3ADY_H4PP3N3D}