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TechKnowSurge Catalog Videos Confidentiality - Steganography
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Confidentiality - Steganography

Steganography is the practice of concealing a message or data inside another file, such as an image or audio recording, rather than encrypting it into an unreadable format. Unlike cryptography, steganography hides the very existence of the message, making it far less likely to attract scrutiny.

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About this video

Steganography is the practice of concealing a message or piece of information inside an ordinary carrier medium, such as an image, audio file, or block of text, so that the existence of the communication itself goes undetected. This distinguishes it from cryptography, which converts data into ciphertext that is openly present but mathematically protected. A steganographic message can be embedded as subtly as using the first letter of every other word in a sentence to spell out a hidden phrase, illustrating that the technique does not require digital media at all. In digital contexts, one of the most widely used steganographic methods exploits the structure of image files. Every pixel in an image is represented by binary values that encode the intensity of red, green, and blue color channels. The least significant bits in those values contribute so little to the final color that flipping them produces no perceptible change to a viewer. By systematically altering those low-order bits according to the binary content of a hidden message, an entire payload can be encoded inside an image without any visible distortion, with larger files offering greater capacity for concealment. The primary advantage of steganography over cryptography is psychological. An intercepted block of ciphertext immediately signals that sensitive information is being protected and invites attempts at decryption. A photograph or audio clip, by contrast, draws no such attention and is likely to pass unexamined. The tradeoff is that once an observer suspects a file contains hidden data, extracting and reading that data can sometimes be straightforward. Because each method has distinct strengths and weaknesses, combining them produces a more robust solution. Encrypting a message with standard cryptographic techniques and then embedding the resulting ciphertext inside a carrier file using steganography means the communication neither appears suspicious nor yields readable content if the hidden layer is detected. This layered approach reflects how steganography functions in practice within broader security and information-hiding strategies.

What you'll learn

What's covered

Steganography

Aligned to

NIST NICE
K0884 Knowledge of covert communication tools and techniques
K0942 Knowledge of cryptology principles and practices
S0652 Skill in performing bit-level analysis
K0694 Knowledge of computer algorithm capabilities and applications
K1094 Knowledge of hexadecimal data
Cisco CCST Cybersecurity
1.4 Explain encryption methods and applications
CompTIA Tech+
6.6 Explain common uses of encryption

Key terms

Steganography
The practice of concealing a message within another medium, such as an image or sentence, so its existence is hidden rather than its content scrambled.
Cryptography
The practice of securing information by transforming it into an unreadable format using mathematical algorithms.
Least Significant Bit
LSB
The lowest-value bit in a binary number, located at the far right, whose modification causes the smallest possible change to the overall value and is used in steganography to embed hidden data with minimal perceptible alteration.
Encryption
The process of converting readable data into an unreadable format using an algorithm and key to prevent unauthorized access.

Topics

Steganography Cryptography Least Significant Bit Data Concealment Digital Forensics Confidentiality

Transcript

Hiding a message instead of encoding it

With encryption, we're actually taking data and converting it into some sort of code. With steganography, what we're doing is hiding our message inside of something else.

Steganography is the art of hiding some sort of message or information inside something else. An example might be that we have some sort of secret message and we're hiding it inside a picture.

So here's what that looks like. We have a secret and we're going to hide it. Cryptography says that we are going to convert that into some sort of code that can be decoded later, or that we're going to encrypt it and then it's going to be decrypted later. Steganography means that we're concealing it inside something else.

A message hidden in a sentence

Maybe it's a message. This is an example where this secret is actually inside this little sentence right here. In fact, we can play a little bit of a game here. See if you can find the word secret embedded inside this message right here. It's embedded in a certain way, so it's very definitive on seeing the word secret in there, but how is it?

Here's the answer. The way it was embedded was the first letter of every second word spells out the word secret. So, did you get it right?

Hiding a message in a picture

If we want to embed a message into a picture, it could be something as even like a sign in the background of the picture that we're looking at and you derive information from there. Or it could be even using the bits of the picture itself. So let's take a look at how we'd actually embed a binary message inside a picture.

A picture actually has a lot of bits to it, and the bigger the picture, the more the bits. It takes a lot of bits in order to represent what a picture is going to look like. A picture is represented in colors, and those colors are going to be represented by binary numbers in how much red, how much green, how much blue, the higher the binary number. So this right here says that it has a lot of blue in it, it has quite a bit of green, and it has a little bit less red in it.

When you're looking at a binary number, and we won't get too in depth into this, the more significant bits are to the left, just as it is with decimal, and the least significant bits are to the right. So we could actually flip this one to a zero right here, or flip this 0 to a 1, without drastically altering any color. It would be a very small change in the color, it would be hardly noticeable at all. So we can take these little bits and we can flip them depending on what our message is that we're trying to convey.

This is a little more of what a picture might look like. We would have all these bits, and this would be a really small picture that this would represent right here, and then every eighth bit could be our secret message that we're encoding in it.

Pros and cons, and combining the two

There are pros and cons to using this method. With cryptography, you have some sort of code that you're passing back and forth. The problem with this is if I were to see a code, I would say, hm, I wonder if I could break the code, and then start trying to work at breaking the code. It's pretty obvious that this is going to be a coded message that's going to go back and forth.

With steganography, if I'm looking at a picture, I don't necessarily know that there's something embedded in it, and so the code could be much more breezed over, and I'm not even going to attempt to try to find a code in it, because it's just a picture. Now, that being said, once I did know, it might actually be easier for me to extract that code and figure out what it's saying.

So maybe what I can do, if I want a secret code that doesn't look like a code, is I could combine these two. I could have cryptography give me some sort of code, and I can embed that into a picture and send it. It doesn't have to be a picture, it could be an audio file. The audio file is also information rich, and we could flip some non-significant bits and we could encode a message and send it that way. Or there are other methods of sending this as well.

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