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Operation: Index of Coincidence #571

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merged 2 commits into from
Jun 27, 2019
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@Ge0rg3 Ge0rg3 commented Jun 8, 2019

This PR adds the Index of Coincidence operation, which calculates the IC of any given text (see here).
This acts as a kind of mix between entropy and frequency analysis, and is often used to automatically determine whether ciphers are decoded.
You can see an example output here.

I capped the graph output at 0.25, as otherwise the data is almost always crammed in the first quarter.

@Ge0rg3 Ge0rg3 force-pushed the index-of-coincidence branch from 2db9409 to 3d1e3f1 Compare June 8, 2019 23:28
@Ge0rg3 Ge0rg3 force-pushed the index-of-coincidence branch from 3d1e3f1 to a6732ba Compare June 8, 2019 23:57
@Ge0rg3 Ge0rg3 changed the title Feature: Index of Coincidence Operation: Index of Coincidence Jun 9, 2019
@n1474335 n1474335 merged commit a6732ba into gchq:master Jun 27, 2019
@Ge0rg3 Ge0rg3 deleted the index-of-coincidence branch June 29, 2019 16:05
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