96 lines
4.0 KiB
HTML
96 lines
4.0 KiB
HTML
<!DOCTYPE html>
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<html lang="en">
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<head>
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<meta charset="utf-8"/>
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<meta name="viewport" content="initial-scale=1.0,maximum-scale=1.0" />
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<title>__FNAME__ – Page Analyis</title>
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<link rel="stylesheet" type="text/css" href="../style.css">
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</head>
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<body>
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<nav class="small">
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<a href="../index.html" class="home"></a>
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<a href="#top">Top</a>
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<a href="#count">Count</a>
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<a href="#double-rune">Double-Rune</a>
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<a href="#ioc">IoC</a>
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<a href="#mod-ioc">Mod-IoC</a>
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<a href="#running-ioc">Running-IoC</a>
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<a href="#concealment">Concealment</a>
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</nav>
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<h1 id="top">Page Analysis: __FNAME__</h1>
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<h2 id="count">Count</h2>
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__SEC_COUNTS__
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<h2 id="double-rune">Double-Rune Occurrence</h2>
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<p>
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The following analysis looks at two neighboring runes.
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Whenever two identical runes appear one after another, the number sequence will print a “1” on dark background.
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Rune difference looks at the shortest distance between two neighbors.
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Maximum value is 14 if they are farthest apart.
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The value is zero if they are identical.
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</p>
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<p>
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<b>Note:</b> Hover on a cell to see the offset in the file.
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</p>
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__SEC_DOUBLE__
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<h2 id="ioc">Index of Coincidence (IoC)</h2>
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<p>
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Quick IoC recap: Normal english IoC is about 1.77.
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Values below 1.4 are highly unlikely to be anywhat meaningful.
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Predicting english text with IoC gets worse if the text is very short.
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</p>
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<p>
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Here we are considering to either ᚠ being an interrupt; or it's inverse ᛠ.
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The numbers (1–32) represent the key length.
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With a key length of 5, every fifth rune will be decrypted with the same alphabet.
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</p>
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<p>
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<b>Note:</b> the darker the cell, the better the prediction.
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The runes per length columns influences the results of the other columns; so if this is low, the other columns are not reliable.
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</p>
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__SEC_IOC__
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<h2 id="mod-ioc">Modulo IoC</h2>
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<p>
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This sections explores the idea of multiple alphabets alternating.
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For example, have two or three Vigenere ciphers that switch after each rune.
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A Vigenere with key length 3 (ABC) plus another Vigenere with key length 5 (DEFGH) will generate a pattern that only repeats after 30 runes (ADBECFAGBHCDAEBFCGAHBDCEAFBGCH).
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So the first group will represent every 2nd rune starting with the first, and the second group will contain every 2nd rune starting with the second.
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</p>
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<p>
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There are two main distinctions.
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Interrupt-first-then-mod assumes that an interrupt will pause the alternation between the different groups.
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Mod-first-then-interrupt assumes that an interrupt will pause the key alternation within that group.
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Lets look at the example Vig(3) + Vig(5).
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With the first, the decryption sequence is: Vig(3)[0], interrupt, Vig(5)[0], Vig(3)[1], etc.
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With the second, the decryption sequence is: Vig(3)[0], interrupt, Vig(3)[1], Vig(5)[0], etc.
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Note that the second decryption still switched to Vig(5) but was ignored because it was an interrupt.
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</p>
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<p>
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<b>Note:</b> The row header format is {interrupt}.{mod}.{offset}.
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“ᚠ.2.0” means, assume the interrupt is ᚠ, divide the data into two sets, then look at the first set (rune at index 0, rune at index 2, etc.).
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The column shows the keylength for which the IoC was calculated.
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In the previous example, with a key length of 7, indices 0, 14, 28, ... are part of one alphabet, and indices 2, 17, 30, ... are part of another alphabet.
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</p>
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__SEC_IOC_MOD__
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<h2 id="running-ioc">Running IoC</h2>
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<p>
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This section perfoms a running IoC with a window size on the whole text.
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For example, a window size of 50 will look at the first 50 runes and calculate the IoC (high).
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This will be the first value in the list.
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The text is offsetted by one and the next 50 runes are evaluated.
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This contiunes to the last set of 50 runes.
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</p>
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<p>
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Same rules apply as to normal IoC; an IoC on 20 runes is just too small to get a meaningful result.
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But it helps to get the bigger picture ;).
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</p>
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__SEC_IOC_FLOW__
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<h2 id="concealment">Concealment Analysis</h2>
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__SEC_CONCEAL__
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</body>
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</html> |