• Author: Robert Winslow
• Source: http://github.com/rw/plainsight
• Email: robert.winslow@gmail.com
• Twitter: @robert_winslow
• Presentation video (8 minutes): http://bit.ly/pecGgW

The goal of Plainsight is to help you avoid being flagged as 'suspicious' by internet censors. By using Plainsight, your data will be enciphered to look like harmless English prose. When you transmit it to someone else, eaves- droppers will only see the written word, and not your data payload.

This is an improvement over just sending an encrypted file, because no suspicious random-looking bitstreams are seen by others.

1. Install it (only Python 2 is supported at this time, due to the path in the executable shim):

    sudo pip install bitstring
    sudo pip install plainsight
   

2. Download a copy of 'The Adventures of Sherlock Holmes'

    curl -o sherlock.txt http://www.gutenberg.org/cache/epub/1661/pg1661.txt
   

3. Type your message to encode:

    echo 'Meet at Union Square at noon. The password is FuriousGreen.' > cleartext
   

4. Then, pipe it through Plainsight:

    cat cleartext | plainsight -m encipher -f sherlock.txt > ciphertext
   

5. The output will be gibberish that Doyle could've written:

    cat ciphertext | fold -s
   
    which was the case, of a light. And, his hand. "BALLARAT." only applicant?" 
    decline be walking we do, the point of the little man in a strange, her 
    husband's hand, going said road, path but you do know what I have heard of you, 
    I found myself to get away from home and for the ventilator little cold night, 
    and I he had left my friend Sherlock of our visitor and he had an idea was not 
    to abuse step I of you, I knew what I was then the first signs it is the 
    daughter, at least a fellow-countryman. had come. as I have already explained, 
    the garden. what you can see a of importance. your hair. a picture upon of the 
    money which had brought a you have a little good deal in way: out to my wife 
    and hurry." made your hair. a charge me a series events, and excuse no sign his 
    note-book has come away and in my old Sherlock was already down to do with the 
    twisted
   

6. Now, decipher that ciphertext:

    cat ciphertext | plainsight -m decipher -f sherlock.txt > deciphered
   
    cat deciphered
   
    Meet at Union Square at noon. The password is FuriousGreen.
   

• More entropic ciphertexts.
  (e.g. play with changing the probability mass as tree depth increases).
• Regression tests (e.g. for EOF).
• Robust adding of files to language model (e.g. independent of args order).
• Model serialization to pickled Python objects.
• Higher throughput.
• Tighter code.
• Support for other languages (e.g. Chinese).
• Port to other languages (e.g. Ruby).

The implementation is not as clear as it should be.

Copyright (c) 2011, Robert Winslow All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

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