Hackernoon logoHiding Secrets: Steganography in Digital Arts and NFTs by@babycommando

Hiding Secrets: Steganography in Digital Arts and NFTs

Image steganography is a technique for hiding files inside other files, being an image, a text, a video, or anything else. Images are just streams of bytes like any other file, making them a particularly effective medium for concealing secret text and other data. The same idea can be used to attach a complete file to an image using the RAR archive format. An image viewer only reads the code related to displaying the image and ignores any other files contained within the archive. A malicious actor or program can easily extract the appended file.
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@babycommandoBaby Commando

Full time hacker based in São Paulo, Brazil. Love C64 demos and trackers. ASCII art/NFT enjoyer. ▬▬ι═══════ﺤ -═══════ι▬▬

“If you want to keep a secret, you must also hide it from yourself.”
― 
George Orwell, 1984

The world of art has always been full of secrets; trying to achieve powerful meanings or sometimes by hiding real-life secrets, messages, treasures, tributes, or techniques... Artists love to put their marks into their art to make them memorable. For example, take software cracking teams - they make NFO ASCII art files for increasing respect in the scene.

But what happens when the whole world, including the art world, enters into the technological revolution?

Blockchain, mixed reality, quantum computing, NFTs, and AI construct a whole new generation where the meaning of art itself has changed. Modern technologies have merged virtual reality with actual reality.

If the world changes, we must find (cool) ways to adapt to it. Definitely, the world of Non Fungible Tokens took over the scene by converting digital formats like JPG, PNG, GIF, GLB, GLTF, MP3, MP4 into something uncopiable, unique.

image

Enter Steganography

steg·​a·​nog·​ra·​phy | \ ˌste-gə-ˈnä-grə-fē \
Definition of steganography:
archaic 
CRYPTOGRAPHY
2: 
the art or practice of concealing a message,image, or file within another message, image, or file.

Steganography is a technique for hiding files inside other files, being an image, a text, a video, or anything else. For example, you can send an image of a cute little cat to a friend that contains a secret text file about a corruption scheme in your government.

Yes, it’s an old friend of computer virus developers also.

image

Images can carry a lot of data that’s normally invisible to the human eye. Many Facebook users discovered the hidden image tags attached to users’ pictures. Though, it's nothing compared to the sophisticated methods threat actors use to craft images that can deliver malicious code in the wild. Some of them are Microcin (AKA six little monkeys), NetTraveler, Zberp, Enfal (its new loader called Zero.T), Shamoon, KinS, ZeusVM, Triton (Fibbit), and more.

Digital images are just streams of bytes like any other file, making them a particularly effective medium for concealing secret text and other data.

image

How Steganography Hides Information

To understand how image steganography works, let’s take a look at some basic ways you can hide text in an image file.

One simple method is to append a string to the end of the file. Doing so does not prevent the image from being displayed normally, nor does it change its visual appearance. Here, we simply append “hello world” to the end of the file. The output from 

hexdump
shows us the extra bytes added.

image

The plain text string can easily be dumped out or read by a program. In this case, we’ll just use the 

xxd
utility to reverse the hexadecimal and print it out in plaintext.

echo 68 65 6c 6c 6f 20 77 6f 72 6c 64 0a | xxd -r -p

image

The same idea can be used to attach a complete file to an image using the RAR archive format. An image viewer only reads the code related to displaying the image and ignores any other files contained within the archive. A malicious actor or program, though, can easily extract the appended file.

In this example, the file 

new.jpg
 displays a picture when opened in an image viewer application, but when inspected using the WinRAR archiving utility, we can see that the unpacked 
.jpg
 file contains a secret 28-byte text file, 
msg.txt
.

image

Sometimes it can get way bigger than the actual image size, which makes it recognizable by antiviruses as a malicious archive. But there is always a way around it. Always.

A better approach is to get down into the code at a binary level and manipulate individual pixels' least significant bits (LSB). Pixels in a color image can be represented by 3 bytes, each for RGB (Red, Green, Blue). Suppose we have three bytes representing one particular color, in this case, orange:

image

The least significant bits — the last four if we’re reading left-to-right — do not make much of an impact on the color’s visual appearance.

1 1 1 1
 1 1 1 1

0 1 1 1
 1 1 1 1

0000
0000

We can change those to anything we like, and the pixel will still look pretty much the same. So, let’s take a completely different color, turquoise, say :

image

100 1
 100 1

1 100
 1 100

1 100
 1 100

And replace the last 4 bits in the code for orange with the first four bits of the code for turquoise to produce this composite RGB:

orange turquoise

1 1 1 1
 100 1

0 1 1 1
 1 100

0000
 1 100

There’s no discernible impact on the appearance of the color this generates.

But if we use a program to read and extract these last 4 bits separately, we have effectively hidden the code for turquoise inside the code for orange. Two pixels for the price of one since there’s no increase in the file size. We can transmit our hidden message without increasing the bandwidth of the original message and without manipulating the file format, so there’s nothing for simple detection methods that rely on file scanning to find.

image

LSB manipulation is only one of several steganographic techniques. There are actually a number of other methods by which images and other kinds of files can be manipulated to hide secret code, such as Palette Based Technique, Secure Cover Selection, Audio Steganography, and many more.

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image
image

There are many software out there that provide automation for these methods of steganography, so we can cipher our information faster.
Seghide is one great option, and here is a good list of more.

Conclusion

As the art world changes, the techniques changes with it. Hiding information or secrets inside work is actually another art by itself. In terms of security, there is no perfect system. Every single technology around us can be exploited to bring new meanings, reflections, and manifestations.

Now it’s up to us, the artists. What wonders and secrets will be written with steganography in the new world being built around us?

Baby Commando

Previously published here.

Baby Commando Hacker Noon profile picture
by Baby Commando @babycommando. Full time hacker based in São Paulo, Brazil. Love C64 demos and trackers. ASCII art/NFT enjoyer. ▬▬ι═══════ﺤ -═══════ι▬▬Read my stories

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