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[tor-bugs] #5384 [Pluggable transport]: Image Steganography for BridgeFinder
#5384: Image Steganography for BridgeFinder
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Reporter: seaman | Owner: asn
Type: project | Status: new
Priority: normal | Milestone: Tor: unspecified
Component: Pluggable transport | Version:
Keywords: | Parent:
Points: | Actualpoints:
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Regarding the design of BridgeFinder, I suggest that it contains a plugin
system in order to allow different inputs. In
https://trac.torproject.org/projects/tor/ticket/5096 it is proposed to use
QR codes but I think that this should not be the only option.
One problem with QR codes is that they are clearly describing something
that is hidden. So instead I propose an additional plugin that does
steganography. In more detail I'm thinking of image steganography
(although at a later stage one could add audio/video or others (random
bytes)).
The basic idea:
A list of bridge addresses get sent to a trusted person. This person
encodes the bridge addresse(s) into an image and sends them to a friend.
This friend then decodes the bridge address contained in the image and
uses it to connect to Tor (via BridgeFinder).
A bit more specific:
# The encoding will not alter the image signficantly so that it appears to
be a valid unsuspicious data exchange (e.g. a holiday snapshot, avatar,
signature).
# To encode the image a password needs to be entered that is known by both
ends. Password suggestions:
# # a complex password known by both parties
# # name of a significant object in the image (this would allow external
people easier access, on the other hand it would also allow the use of
image sharing websites and blogs, automatic algorithms (object detection)
to treat large amounts of images would be difficult).
# # I can also think of images that contain no password at all. But of
course that would make it easier for censors to find them and block the
bridges.
# The decoding process must be computationally expensive in order to avoid
dictonary attacks.
# The algorithm for decoding contains automatic error correction as well
as data verification.
Let me know what you think about this idea. If it is worth pursuing I can
do the coding.
--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/5384>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online
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