Simple Steganographic Store (scubed)

Deniable encryption in GNU/Linux with dm-crypt and dm-linear
Introduction | Download | Documentation | Links | Contact

Introduction

With rubberhose (wayback machine search) gone, stegfs vast asleep and phonebook having a (IMHO) weird and complex architecture (and dependencies on fuse and Python), the GNU/Linux user wanting plausibe deniability is at a loss. Until now...

Let me introduce the Simple Steganographic Store:

Simple, the program is small, easy to understand, maintain and use.
Steganographic, it should provide the user with deniable encryption.
Store, it can be read from and written to through blockdevices

WARNING: You should see this program as an unreviewed bug-ridden hack. If you seriously need deniable encryption and you want to use this program, you are free to do so, but you should put it up for technical and legal review. Don't trust the stuff you read here, even though IANAL. Don't say I didn't warn you.

How is plausibe deniability implemented? First some terminoligy. There is a raw device which contains the encrypted data. Using cryptsetup and scubed you can create at most between 512 and 1024 cryptographic views on the raw device. I will call those cryptographic views partitions.

Suppose you use scubed on a DVD+RW which can hold 4.377 GB. You have a partition of 2 GB, one of 1 GB and one of 600MB. This leaves about 0.791 GB of free space.

Now someone demands your encryption keys, this someone cannot see how many partitions you have, so you could give the keys to the first two partitions and claim that the rest is free space (reserved for a new partition or for expansion of an existing partition to enlarge the filesystem it contains).

Without the right passphrases even scubed itself can't say if the free space is truly free or is partly occupied by a hidden partition. This is why you need to tell scubed about all your partitions before you enlarge a partition or create a new one.

A small tutorial is contained in the README file.

Download

The latest development version of this program lives in a subversion repository which can be browsed using viewvc. Also there is public read-only access to the repository. If you have installed subversion, the source can be checked out by typing

svn checkout 
http://cube.dyndns.org/svn/scubed/trunk scubed

. This command will create a directory scubed/ in the current directory and populate it with files.