CDR: Re: stego for the censored

[Michael Motyka]

>
> I'm currently looking for a way to get encrypted data via stego to
> people who live in countries where crypto is illegal, and who may be
> watched. so just sending them a large graphic would likely arouse
> suspicion.
> 
> the 2 best solutions I've come up with so far are porn and spam. both
> are readily believable, even in large quantities.
> the problem with porn is that it may be illegal in itself in the same
> countries. the problem with spam is that ascii text just doesn't offer
> much to hide stego in (whitespacing, etc. is both easy to find and can
> store very little data).
>
Since the amount of information you need to send and the channel/event
capacity for stego'd information are unspecified maybe you're looking
for a general solution. Part of a general solution might be a
scatter-gather mechanism.

XMIT

The information you need to send is broken up into multiple pieces and
an index. The simplest method would be a flat structure but a tree is
acceptable. Redundancy via overlapping segments could be introduced.
Redundancy/error correction might be useful if Mallet is inclined for
example to mess with whitespace in your e-mail. Anyway, the pieces are
stego'd into multiple carriers that are made available via any and all
protocols. 

RCV

Once a recipient has the top-level index they can gather the pieces and
reconstruct the original. 

Notes

Scattering the information over multiple sites and accessing it via
valid sets of linked pages for example might help in disguising the act
of retrieving any particular carrier. A typical browse sequence might
include many unused files and only one carrier. 

A single carrier might serve various fragments from multiple original
input documents intended for different recipients. 

If a single carrier is safe and acceptable a webcam might be a nice
broadcast for a few channels of text. It does simplify the task of
identifying the sender and making a list of possibly recipients. A
shifting set of sources would probably be safer.

Message fragments could be transmitted over any period of time with the
top-level index being the final step. That would help the sender avoid
detection of the actual transmission since it could be interleaved with
other activities.

Likewise reception could be over an arbitrary period of time and
interleaved with other activities.

***

There's a high bandwidth cost associated with the scatter-gather process
but it does allow arbitrarily sized messages and I'm assuming the cost
of getting caught is extremely high as is the desire of authorities to
view content, locate the sender or other recipients and suppress the
information if it is detected.

Mike