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Robbers thread

Your task is to create a method for hiding information in an image. You will post three encoded messages of your choice (keep them classy), each with its associated image. Reveal the messages for the first two images and do not reveal the third. Robbers have the task of determining what your third hidden message is, along with an explanation of how your system works.

Rules and Scoring

  • Any data aside from the image required to make your algorithm work must be revealed openly and be constant across all possible message encodings.
    • For example, you may have a book cipher referencing The Great Gatsby (which is in the public domain as of January 1, 2021) as long as you link to the exact text required to make your system work.
    • RNG and Cryptographic algorithms are allowed under this caveat. Robbers should not be required to guess cryptographic secrets such as keys, hashes, salts, or initial seeds, as that easily makes cracking any given challenge infeasible. That would ruin the fun.
    • Do not share irrelevant information, e.g. "It's one of these 100 books" when you only use 1, or revealing a key which you don't use at all in your system, etc...
  • Data may not be hidden entirely in image metadata; you must incorporate at least one bit of one pixel in your system of encoding.
  • The encoded messages must be in English.
  • The encoded message does not need to be easily machine-readable (though it's perfectly acceptable if it is), but must be reasonably legible as rendered.
    • For example, you could have the message manifest itself as a rendering in Arial. Or perhaps it renders as a figlet font in ascii art.
    • The hidden message being rendered in something like Wingdings would be unacceptable, however. Using a frilly gothic font is probably pushing it.
  • You may encode the message as audio as long as it is intelligible to a fluent English speaker.
  • The encoded message should always be in the same format. So for example, using a rendered hidden text image for one message, an audio recording for the second, and plain text for the third, would not be allowed.
  • Data required to render the message as an image or audio is not considered part of the data required to make your algorithm work (which you would otherwise need to reveal)
  • A rendered encoding must be intelligible as-is and not require additional processing, e.g. a ROT13 cipher.
  • You may post more than 3 hidden messages if you wish, but keep in mind this is probably a disadvantage.
  • You may only encode one message in the image. No (intentional) decoy messages.
  • It's not required per-se that the images hiding your messages look like anything (e.g. cats, dinosaurs, scenic vistas, etc...), but you're no fun if they look like random noise and I will be downvoting any post that uses examples that do.

You will score 1 point if your system remains uncracked after 7 days.

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  • 6
    \$\begingroup\$ Needing both an ASCII art as well as an image in combination to encode the message strikes me as overly complicated. I think this challenge would be more accessible if it were just one or the other. \$\endgroup\$
    – xnor
    Apr 9, 2021 at 15:57
  • \$\begingroup\$ "Data hidden in the image must be hidden in the pixel data rather than headers or how the image is encoded; your system should still work if the image is converted to another lossless format." doesn't that ruin all the interesting things and restrict us to LSB steganography? If there are 10 ways to hide information in an image, 10 ways to hide it in ASCII art and 10 ways to combine them, don't we have to try 1000 different things to win? (this question has my imaginary downvote now; it's not an actual one because an actual one would magically push it to +5 in a few minutes) \$\endgroup\$ Apr 9, 2021 at 16:07
  • \$\begingroup\$ @Arnauld - yeah, that's pretty much what I had in mind. \$\endgroup\$
    – Beefster
    Apr 9, 2021 at 16:11
  • \$\begingroup\$ @xnor I'm going to feel it out for a few days and remove the ascii art element if there are no submissions by monday. \$\endgroup\$
    – Beefster
    Apr 9, 2021 at 16:12
  • 1
    \$\begingroup\$ One potential problem I see with allowing data to be hidden in png metadata is that imgur might mangle it during uploads \$\endgroup\$
    – Beefster
    Apr 9, 2021 at 16:18

9 Answers 9

7
\$\begingroup\$

RRRGGGBBB!!! Cracked by Unrelated String

Difficulty: Easy

First image: HELLO,WORLD!

Red

Second image: COPS AND ROBBERS

Green

Third image

Blue

Title inspired by rrrgggbbb.com

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4
  • \$\begingroup\$ AFAICT, these images are pure #f00, #0f0, and #00f, respectively, so I don't see how a message could be encoded in the pixel data. (Note that hiding the message in image metadata isn't allowed) \$\endgroup\$
    – tjjfvi
    Dec 21, 2021 at 3:02
  • 1
    \$\begingroup\$ @tjjfvi I can confirm the data is stored in the pixels. I can't give any more hints without pretty much giving the answer away \$\endgroup\$
    – CreaZyp154
    Dec 21, 2021 at 9:36
  • 1
    \$\begingroup\$ Cracked \$\endgroup\$ Dec 21, 2021 at 12:55
  • \$\begingroup\$ @alephalpha (15 chars) \$\endgroup\$ Jan 10, 2022 at 5:38
4
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Low difficulty

Image 1:

ABCDabcd01::::

A cat, whose name is Scully, sleeping. The image itself doesn't matter, of course.

Image 2:

Fun fact: The practice of designing a cryptographic algorithm which itself uses cryptography to allow the designer of the algorithm to read any message is known as "kleptography" (not relevant to this, just an interesting field that's a friend-of-a-friend of steganography)

A llama, with wheels. The image itself doesn't matter, of course.

Image 3:

Crack this one!

A snowy field. The image itself doesn't matter, of course.

Hints

Hint 1:

Only one color channel is relevant. Look for odd patterns.

Hint 2:

Try looking at the parity of things. (You'll know what these "things" are when you see them)

Hint 3:

Symmetry matters, but not necessarily the visual symmetry.

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  • 2
    \$\begingroup\$ md5sum for these images: 4bf4130af67681416775706b9399002b (cat), 46c897e0588c289f52864a55f5d86871 (llama), 7766488bbc2f3a849aff5d97d555791c (snow) \$\endgroup\$ Dec 16, 2021 at 19:14
  • \$\begingroup\$ Probably safe now? \$\endgroup\$
    – emanresu A
    Dec 26, 2021 at 7:56
3
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Cracked by Redwolf Programs

enter image description here

Message: HI

enter image description here

Message: BYE

enter image description here

So what is this one?

I'll see what happens....

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1
3
\$\begingroup\$

Feline Steganography

Image 1: feline steganography

Image 1

Image 2: what could it be?

Image 2

Image 3: ???

Image 3

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  • \$\begingroup\$ Not a crack, but I think I can finally make out a cat shooting beams from its eyes and mouth in your profile picture...? \$\endgroup\$ Dec 21, 2021 at 13:12
  • 2
    \$\begingroup\$ @UnrelatedString Close; those are its whiskers \$\endgroup\$
    – tjjfvi
    Dec 21, 2021 at 17:23
  • \$\begingroup\$ Safe now (I think?) \$\endgroup\$
    – emanresu A
    Dec 27, 2021 at 19:56
  • \$\begingroup\$ @emanresuA Probably, yeah, but I’ll let it stick around for a little longer since it’s the holidays \$\endgroup\$
    – tjjfvi
    Dec 27, 2021 at 21:31
2
\$\begingroup\$

Medium difficulty

Image 1:

hello world

image one

Image 2:

llama with wheels

image two

Image 3:

image three

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2
  • \$\begingroup\$ This issafe now \$\endgroup\$
    – emanresu A
    Dec 26, 2021 at 7:57
  • 1
    \$\begingroup\$ @emanresuA Sadly, this is actually not possible to crack. I'm working on a new one that is. \$\endgroup\$
    – Ginger
    Jan 6, 2022 at 13:13
2
\$\begingroup\$

Should be easy

Image 1:

first image used

This was a really astoundingly terrible idea, come to think of it

Image 2:

second image used

posed look

Image 3:
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  • 1
    \$\begingroup\$ Oh, seeing your old pfp at that size I finally see how it was supposed to be Ryze originally :P \$\endgroup\$
    – hyper-neutrino
    Dec 18, 2021 at 19:11
  • 1
    \$\begingroup\$ I think this is safe now \$\endgroup\$
    – emanresu A
    Dec 26, 2021 at 7:56
  • \$\begingroup\$ @emanresuA I'm worried this might be too far into a grey area with the no hidden keys rule, so I might post a revised version without the possibly-offending bit before claiming the point \$\endgroup\$ Dec 26, 2021 at 8:22
2
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The sort you'd expect

Image 1:

These are colorful for a reason!

A rainbow

Image 2:

Stock photos FTW

Oil paints

Image 3:

Crack this one!

Multicolored clothes in a closet

Hint 1:

The title is a hint

Hint 2:

This was inspired by emanresu A's cop

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1
  • \$\begingroup\$ Thissis safe now \$\endgroup\$
    – emanresu A
    Dec 26, 2021 at 7:57
2
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Medium

Note: I had to update the images due to a problem with the encoder, be sure to redownload them if needed

Image 1:

explore the universe

Image 1

Image 2:

no transparency?

Image 2

Image 3:

Image 3

Hint 1:

The first pixel of the image is the only one where the green channel is important.

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1
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Should be easy for real this time

Image 1

This is a simplified version of my previous cop, and very directly so. I hope you can already guess at the basic principle of it, but I would strongly caution against trying to do this by eye alone.

enter image description here

Image 2

In combination with salt, this liquid will give the sea a flavour of the kind of lemonade known as aigresel. It will thus be easy to remove the saline and citric particles from the water and render it drinkable, which will make it unnecessary for ships to be provisioned with barrels of water. This breaking down of sea water by the boreal liquid is a necessary preliminary to the development of new sea creatures, which will provide a host of amphibious servants to pull ships and help in fisheries, replacing the ghastly legions of sea-monsters which will be annihilated by the admixture of boreal fluid and the consequent changes in the the sea’s structure. The sudden death of all of them will rid the Ocean of these vile creatures, images of the intensity of our passions which are represented by the bloodthirsty battles of so many monsters.

--Charles Fourier, apparently (there's only supposed to be one newline)

enter image description here

Image 3

enter image description here

Hints even though it's already been a week:

An image composed entirely of red and white of the same intensity (by some measure) could not encode a message. Replace either with yellow, and it could.

The message is encoded in UTF-8.

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