Steganography

I believe that I have solved the challenge, but the flag is not recognized. Can someone tell me if there is more to the challenge. Here is what I have done until now (trying not to reveal to much):

From original PDF we get a JPG image, from that JPG image we get a PNG image and from PNG image we get just random looking file that begins with text that looks like flag: [Ech0 : spoil] (characters hidden for your protection!) But I am unable to validate the challenge with that flag. Is there something more to the challenge???

The rest of the last file is just random bytes. I tried to play around some more with it and I got it to something recognized as DOS COM executable, but running it DosBox produces no result.

Solved. It was my error. I need to triple-check when copying by hand. There was an error in the last phase, which made the flag corrupt in just 1 character. Thanks to pickle for nice challenge.

Hi!
I passed the PDF > JPG > PNG steps but I’m stuck at how to get something out of the PNG. It seems the more I read the hint (comment) the less I understand where it is supposed to lead me (knowing I need to pay attention only to what is in uppercases didn’t really help me 😕).
Any hint pleeeeeease ? (I’m desesperate)
Thanks !!
[EDIT] finally got it 😄)

"Pay attention to the UPPERCASE.." is the way to go! Anything more we say it will be to much spoil.

Hi, please a little hint for the part with PNG?

The PNG itself contains the best possible hint (I suppose that you have found the hint in PNG). I believe that it is not possible to give any better hint without completely spoiling this step. Just persevere, you are near the end.

Hello, I also ask for a clue to the last step, everything read in this thread did not help me. I already tried to assume that the "hint" in capital letters is the key or something but nothing work.

there is more.

Hello , Do i need Dosbox ?

No

Solved ! thks

Hello,

I’m stuck with the png step. I don’t see how to get the key and the iv from the comment. I have tried many combination from the comment but nothing.
Any help plz :s

Thank you in advance.

The key is not in the comment. The comment is just a hint how to get the key and iv.

Thank you for your answer. I’m thinking about the hint and its meaning.

Hi everybody! I’m trying to complete this challenge but I’m having a problem with iv.
I’m using python to decrypt/encrypt files, but when I try to create the object DES3.new(key, MODE_CBC, iv) it gaves me an error for bytes long... I’m converting iv to bytes using bytes.fromhex(iv)... am I in the wrong way? can anybody giveme a hint? jeje

Try more modern algorithms. As Einstein Said: If you don’t succeed, try again.

Ok, Now im stuck in the PNG step :v I just need to know something... if I’m doing thing right, wil i get something saying "flag: ****** iv: ******"??
[EDIT] I got the flag!!!!!

Putain j’en ai bien chié pour celui là, il aurait mérité bien plus de 30 points.