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Thread: Slow but strong compression idea

  1. #1
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    Slow but strong compression idea

    What if we use hashcat to bruteforce multiple fast hashes of fragments of file at the same time?
    There would be need for fast hashes, filesize, few first and last bytes and maybe entropy.
    Has anyone tried that?

  2. #2
    Administrator Shelwien's Avatar
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    May 2008
    Kharkov, Ukraine
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    Hashes are lossy.
    > md5sum *_*
    79054025255fb1a26e4bc422aef54eb4 *md5_1
    79054025255fb1a26e4bc422aef54eb4 *md5_2
    2a8c87d415a369eeb396d17df6241c57 *sha1_1
    d27794ba8bc1f19e97ec82fea19a231e *sha1_2
    > sha1sum *_*
    a34473cf767c6108a5751a20971f1fdfba97690a *md5_1
    4283dd2d70af1ad3c2d5fdc917330bf502035658 *md5_2
    8ac60ba76f1999a1ab70223f225aefdc78d4ddc0 *sha1_1
    8ac60ba76f1999a1ab70223f225aefdc78d4ddc0 *sha1_2
    It may be possible to use hashing as a replacement for entropy coding, to produce a codec with reverse asymmetry
    (fast encoding/slow decoding; in a way, some dedup algorithms already do work like that - only check hash matches rather than full data blocks).
    But you can't rely on bruteforce for reconstruction of input string - its lossy and too slow even for password hashes.
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