Hide Secret Files Inside Images on Linux Using Steghide

Steganography is the technique of concealing a file within another file to transmit information without raising suspicion. This article shows how to hide a simple text file inside a JPEG image on a Linux system using the steghide tool.

Prerequisites

First, install the necessary development libraries and the steghide program:

sudo apt install -y libjpeg-dev libmcrypt-dev libmhash-dev

sudo apt install steghide

Embedding the Secret File

Generate the MD5 checksum of the cover image to later verify changes: md5sum linuxmi.jpg Create the secret text file: echo "这是超级机密文档" > linuxmi.txt Check its checksum as well: md5sum linuxmi.txt Embed the text file into the JPEG using: steghide embed -cf linuxmi.jpg -ef linuxmi.txt You will be prompted to enter and confirm a passphrase; after completion the tool reports “done”. The command options mean:

steghide : the program name.

embed : operation to insert data.

-cf : specifies the cover (media) file.

-ef : specifies the file to embed.

Verify that the image has changed by checking its MD5 checksum again:

md5sum linuxmi.jpg

Extracting the Hidden Data

To retrieve the secret file from the modified image, run: steghide extract -sf linuxmi.jpg The tool will ask for the passphrase and then write the extracted data to the original filename (e.g., linuxmi.txt). Verify the extraction by displaying the file and checking its checksum:

cat linuxmi.txt

md5sum linuxmi.txt

Conclusion

You now understand the basics of steganography on Linux and can successfully hide and retrieve text files within JPEG images. Steghide also supports BMP, WAV, and AU files as cover media, and you can consult its manual pages for additional options.