*** D A N G E R O U S ***
             *** M U N I T I O N S *** 

These programs make use of strong encryption technology. Possession, import or export may be illegal in your country.

They are licenced under GPL and you use them at your own risk.

Hide and Seek for Linux

These two programs let you hide a file in a jpeg file and then let you recover it later.

There are many similar programs but "jphide" and "jpseek" have a big advantage over any others I have seen. They distribute the hidden file in the jpeg so that not only are the visual effects minimized but also the statistical effects. Simple programs which store the hidden file in low order bits result in jpeg files which are so statistically different from normal jpeg files that the hidden file can be recovered with ease.

"jphide" uses the Blowfish algorithm to provide a stream of pseudo random control bits which determine where to store the bits of the hidden file. The program asks for a pass phrase to initialize this stream. Although the hidden file is "encrypted" by this process I strongly recommend that you encrypt the hidden file before insertion into the jpeg.

Using jpeg files of about 200Kb, up to 20Kb can be inserted with minimal visual and statistical effect. Up to about 35Kb is often possible at the cost of visual and/or statistical effects. The program will refuse to insert even more because it is just too obvious in the resulting jpeg file.

Note that if the original jpeg file is available then a hidden file can always be detected (but it cannot be extracted without the pass phrase). Always use originals that you have scanned yourself and destroy the original afterwards. A reasonable alternative if you have access to very high quality jpegs is to make a cropped and lower quality version of about 200 to 300Kb; again this must be destroyed after making the jpeg containing the hidden file.

Instructions

jphide input-jpeg-file output-jpeg-file file-to-be-hidden

jpseek input-jpeg-file output-hidden-file

Building the programs

Just type make.

Install "jphide" and "jpseek" in your /usr/local/bin or wherever.

Conclusion

This pair of programs offers you the ability to hide a file in such a way that you can later deny that the resulting jpeg contains a hidden file. Always use original scans and destroy them afterwards. Do not try to hide more than about 10% of the file. If you are paranoid you can keep jphide and jpseek on a floppy and be prepared to physically destroy it. It is then even more difficult to prove that you have anything other than normal jpegs.

If you decide to improve these programs please make the results public domain and post them so that others can enjoy them. The security of your own hidden files does not depend on keeping your modifications secret.

Revision 0.3 Allan Latham alatham@flexsys-group.com Revised 2012/02/03 by Dan Church amphetamachine@gmail.com