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Re: Analysing a (binary) string. (rare, distances)

by tye (Sage)
on Jun 28, 2013 at 04:46 UTC ( #1041136=note: print w/replies, xml ) Need Help??

in reply to Analysing a (binary) string. (Solved)

Find the least common byte value(s) and look at how far apart they are. Look for repeating patterns in those differences, thus reducing the size of the problem probably by orders of magnitude. Verify which of these repeating patterns of differences actually represent repeating patterns of bytes.

- tye        

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Re^2: Analysing a (binary) string. (rare, distances)
by BrowserUk (Pope) on Jun 28, 2013 at 06:04 UTC
    Find the least common byte value(s)

    That is an utterly excellent notion. Thank you.

    Doing frequency analysis on several of my strings produces stats like this:

    [ undef, 614567, 614576, 785984, 225487, 262875, 174368, 67367, 28011, 30654, 4738, 6848, 3784, 592, 435, 175, 8, 14, 2, ]

    Of course, some of those low numbers could be due to the errors, but looking for common differences in the positions of the characters in the reverse of that ordering should confirm or deny my hypothesis very quickly.

    With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.

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