[tor-bugs] #5384 [Pluggable transport]: Image Steganography for BridgeFinder

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#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.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/5384>
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