Steganography | Hiding Data in a Video | Steghide

An Art of Hiding & Extracting Data | A clue that matters!

Only a clue can save them!

The room was dim, the air thick with silence, broken only by the flickering light of a paused video frame on the screen. To the untrained eye, it was just another ordinary, mundane recording. But hidden beneath the surface of those moving images lay a secret, buried deep within the pixels. This wasn’t just a video; it was a vault, a vessel of concealed truths. In the shadows of data and deception, steganography becomes the art of the unseen, a digital sleight of hand. This story isn’t about what you can watch, but what you can’t see. And in the world of video steganography, every frame holds a whisper… if you know where to look.

Video Steganography

Video steganography is the practice of concealing secret data within a video file in such a way that its presence remains undetected. Unlike encryption, which obscures the content, steganography hides the existence of the message itself. By subtly altering the pixels, frames, or audio components of a video, information can be embedded without noticeably changing the file’s appearance or quality.

Practical

Download the video you plan to use for embedding the hidden information, for instance, a file named test.mp4. Then, create a text file containing the secret data you want to hide; in this case, the file holds a quotation.

Steghide

Steghide is a command-line tool used for embedding data within image or audio files, allowing for covert communication through steganography. It supports formats like JPEG, BMP, WAV, and AU, and it can encrypt the hidden data with a passphrase for added security. The tool can both hide and extract information without noticeably altering the host file’s appearance or sound.

Installation

sudo apt update
sudo apt install steghide
  ---> You can read manual 
  man steghide
  ---> How to use steghide
  steghide --help

Process of steganography using steghide

help command

1st Step: Extract Audio from the Video

In the case of images, it is often possible to directly embed a text file using steganographic tools without damaging the file. However, when it comes to video, this approach becomes more complex due to the structure of video files, which contain multiple streams such as video, audio, and subtitles. Instead of embedding data directly into the video, a more effective technique is to extract the audio track and use it as the carrier for hidden information. Importantly, the extracted audio should not be in MP3 format. This is because MP3 is a lossy compression format that discards parts of the audio data to reduce file size, which can corrupt or completely remove any hidden content. For steganographic purposes, a lossless format like WAV is preferred, as it preserves the raw audio data and ensures that embedded information remains intact and recoverable.

Command and Explanation

ffmpeg tool

ffmpeg -i test.mp4 -vn -acodec pcm_s16le audio_extract.wav

-i test.mp4 – input file (your video).

-vn – "video none": disables video output (audio only).

-acodec pcm_s16le – sets audio codec to PCM signed 16-bit little-endian (raw WAV format).

audio_extract.wav – output audio file in .wav format.

PCM (Pulse Code Modulation) is a method of digitally representing analog audio by taking thousands of small “snapshots” of sound each second, known as samples. It’s similar to capturing many photos of a moving object; the more you take, the smoother and clearer the motion appears. In the same way, a higher sample rate results in more accurate sound reproduction. PCM is raw and uncompressed, making it ideal for steganography, where preserving audio quality is essential.

s16 (signed 16-bit) refers to the bit depth used for each audio sample. With 16 bits (or 2 bytes) per sample, this format can represent values from -32,768 to +32,767. Because it supports both positive and negative values, it accurately reflects the direction of sound waves. It offers good audio quality and is commonly used in steganographic tools like steghide.

le (Little Endian) defines the order in which bytes are stored in memory. In Little Endian format, the least significant byte is stored first. For example, the number 1234 would be stored as 34 12. This format is important because it matches the memory structure of most modern processors (Intel, AMD), ensuring wide compatibility.

Results

audio_extract.wav file is created

2nd Step : Embed Secret Data into the Audio File

The next step is to embed the secret.txt file into the audio audio_extract.wav file.

Command and Explanation

Hiding Data in an Audio File (stego_audio.wav)

steghide embed -ef secret.txt -cf audio_extract.wav -sf stego_audio.wav

embed – operation to hide data.

-ef secret.txt – embed file: the secret message you want to hide.

-cf audio_extract.wav – cover file: the carrier audio.

-sf stego_audio.wav – stego file: the new audio file with secret embedded.

You'll be prompted to enter a passphrase – this acts as a key for later extraction.

Results

stego_audio.wav, the new audio file with secret embedded

3rd Step : Merge Stego Audio Back into the Video

The next step is to merge the modified audio file back into the video file. This command will create a video file by the name of output_stego_video.mp4.

command

Command and Explanation

ffmpeg -i test.mp4 -i stego_audio.wav -c:v copy -map 0:v:0 -map 1:a:0 -c:a pcm_s16le output_stego_video.mp4

-i test.mp4 – original video file.

-i stego_audio.wav – the audio with hidden data.

-c:v copy – copy the video stream without re-encoding (preserves quality).

-map 0:v:0 – map video from input 0 (the original video).

-map 1:a:0 – map audio from input 1 (the stego audio).

-c:a pcm_s16le – ensure audio remains uncompressed WAV format.

output_stego_video.mp4 – output file with the original video + stego audio.

Results

Checking video File size before and after this procedure

The size may change.

To get our secret file back, we need to extract audio from the video first. Once the audio is extracted, the next step is to extract the text file from the audio file. For our convenience, let’s copy and paste output_stego_video.mp4 into a separate directory. Once it’s done, the next steps are as follows.

Step 1: Extract Audio from the Stego Video

The command will remains the same as we already done this step previously

Command and Explanation

ffmpeg -i output_stego_video.mp4 -vn -acodec copy extracted_stego_audio.wav

-i output_stego_video.mp4 – input is the video with stego audio.

-vn – disable video (extract audio only).

-acodec copy – copy the audio stream as-is (no re-encoding).

extracted_stego_audio.wav – extracted WAV file, still holding the secret message.

Results

Results

Step 2: Extract the Hidden Message from the Audio

The extracte_stego_audio.wav file contains the text file that we are going to extract next.

Command and Explanation

steghide extract -sf extracted_stego_audio.wav -xf recovered_message.txt

-sf extracted_stego_audio.wav – audio file containing the secret.

-xf recovered_message.txt – output file for the recovered message.

Results

recovered_message.txt

viewing data

For image steganography, you can read my article:

[embed]Steganography | Hiding Data in an Image | steghide True Detective: Learn and Implement.medium.com

Thank you for reading my article. I hope it gave useful information and practical expertise. If you have any questions or ideas or just want to explore this issue more, please contact me.

📧 Contact me at: 99alibinazam@gmail.com

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