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Thread: Lightweight compression with encryption based on Asymmetric Numeral Systems

  1. #31
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    Pure tANS encryption is intended only for flower-pot-type of situations: where usually there would be used no encryption and practically the only attacks are cipher-text only: to feed with your plaintext like here (your sequence of rare symbols would need jumping through extremes), you would need to steal the plant ... and you could only get tables for this single flower pot, its tables don't bring any information about the key (are generated using CSPRNG).

    But generally there should be also some additional inexpensive encryption layer - operating on large blocks like 64bit in single round of AES.

  2. #32
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    Quote Originally Posted by Jarek View Post
    Pure tANS encryption is intended only for flower-pot-type of situations: where usually there would be used no encryption and practically the only attacks are cipher-text only: to feed with your plaintext like here (your sequence of rare symbols would need jumping through extremes), you would need to steal the plant ... and you could only get tables for this single flower pot, its tables don't bring any information about the key (are generated using CSPRNG).

    But generally there should be also some additional inexpensive encryption layer - operating on large blocks like 64bit in single round of AES.
    I'm not sure what you mean by flower-pot-type situations. You don't necessarily need to feed your own plaintext. Sometimes parts of the message are predictable. The Allies used the technique in WWII. They knew that virtually all German transmissions ended with "Heil Hitler".

  3. #33
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    Predictable means frequent here - for delta filter the most predictable is zero value: that humidity has nearly not changed, making it a very frequent symbol in tANS symbol spread.
    By flower-pot-like situations I have meant common sensors nobody would bother to encrypt, as this means additional HW and energy cost, and you want the chip to cost ~5cents and being able to gather e.g. on average 1bit/s for 10 years on 1 AAA battery.
    Here imperfect encryption is just a bonus for adding compression.
    However, adding an inexpensive encryption layer, like single AES round, allows to cheaply protect against the weaknesses of pure tANS encryption - the question is how to choose the details.
    And additional cheap but extremely powerful protection is frequently generating new tables, e.g. every 30kB block in standard compressor - CSPRNG makes them completely independent - a sophisticated attack against one block gives no information about another block.

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  5. #34
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    We got a grant for tANS with simultaneous encryption e.g. for IoT with https://en.wikipedia.org/wiki/Josef_Pieprzyk - if somebody would be interested in a cryptology-compression-focused postdoc:
    https://www.dropbox.com/s/13gey4cf4l...yk_postdoc.pdf

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