F5

File Format
Name	F5
Ontology	Electronic File Formats Encryption Steganography F5

F5 by Andreas Westfeld is an algorithm for BMP, GIF, and JPEG steganography.

Release 11 adds the switch "-c comment" to change or remove the default comment in the file. The JPEG compressor's comment header "JPEG Encoder Copyright 1998, James R. Weeks and BioElectroMech. " is very uncommon. If you change (or remove: -c "") the comment header, also the version of the APP0 marker is changed to the more common version 1.01.

nsF5 (non shrinkage F5) is an evolution of F5 that can hide more information.

Implementations

• F5 Release 11+
  • skips every second coefficient the absolute value of which is 1. This is the first try to prevent Mohammed's attack.
• F5 Release 11
  • Original
  • GitHub mirror with some bugfixes and Docker image
• Stegosuite
• F5 Steganography in Java (GitHub)
• Matlab implementation of F5 (GitHub)

Links

• Archived homepage
• F5—A Steganographic Algorithm- High Capacity Despite Better Steganalysis
• Steganalysis of JPEG Images: Breaking the F5 Algorithm
• Stego key recovery method for F5 steganography with matrix encoding
• Detected by Aletheia
• Detected by Stegdetect
• Statistically Undetectable JPEG Steganography: Dead Ends, Challenges, and Opportunities (nsF5)
• Mod4 vs F5