Hide Audio & Protect Files

TL;DR

This guide shows you how to hide secret audio messages inside other files (steganography) and add basic protection to prevent easy copying (Digital Rights Management – DRM). We’ll cover tools for both, plus discuss the limitations of these methods.

Audio Steganography

Steganography is hiding information in plain sight. With audio, this means embedding a secret message within an existing sound file so it’s not obvious to listeners.

1. Choose Your Tools

• Steghide: A command-line tool for Linux and macOS (also available on Windows via Cygwin). Powerful but requires some technical knowledge.
• DeepSound: A free, GUI-based tool for Windows. Easier to use than Steghide.

2. Using Steghide

1. Install Steghide: On Debian/Ubuntu:

   sudo apt install steghide

   On macOS (using Homebrew):

   brew install steghide

2. Embed Audio: Use the following command. Replace secret.wav with your audio file, and cover.mp3 with the file you want to hide it in.

   steghide embed -cf cover.mp3 -ef secret.wav -p "your_password"

   You’ll be prompted for a password – remember this!

3. Extract Audio: Use the following command, providing the same password as when embedding.

   steghide extract -sf cover.mp3 -p "your_password"

   The extracted audio will be saved in the current directory.

3. Using DeepSound

1. Download and Install: Get DeepSound from DeepSoftware’s website.
2. Embed Audio: Open DeepSound, select the cover file (the one you’re hiding in), then go to File > Embed. Choose your secret audio file and set a password.
3. Extract Audio: Open the steganographic file in DeepSound, go to File > Extract, enter the password, and choose where to save the extracted audio.

Basic DRM (Digital Rights Management)

True DRM is complex. We’ll cover simple methods to deter casual copying.

1. Password Protection

• Audio Editors: Most audio editors (Audacity, Adobe Audition, etc.) allow you to export files with passwords. This prevents opening the file without the password.
• File Encryption Tools: Use tools like 7-Zip or VeraCrypt to encrypt the entire audio file.

2. Watermarking

1. Audacity: Audacity can add a subtle watermark to your audio.
   • Generate a short, unique sound (e.g., a sine wave).
   • Import the audio file into Audacity.
   • Add the generated sound as a new track.
   • Lower the volume of the watermark significantly so it’s barely audible.
   • Mix and export the audio.

3. File Format Considerations

• Lossy vs. Lossless: Using a lossless format (FLAC, WAV) makes it easier to detect watermarks or embedded data compared to lossy formats (MP3, AAC). However, lossless files are larger.
• Metadata: Avoid storing sensitive information in metadata tags as these are easily accessible and editable.

Important Limitations

• Steganography is not secure: Experienced users can detect hidden data with specialized tools. It’s best for hiding small amounts of information, not large files.
• DRM is easily bypassed: Simple DRM methods are only effective against casual copying. Dedicated attackers will find ways around them.
• Password Strength: Use strong, unique passwords for both steganography and DRM.