Index of Coincidence

Category: Analysis

Status: Registered and callable in the CyberChef 11.3.0 compatibility inventory.

Input / output: string → number

Background: https://wikipedia.org/wiki/Index_of_coincidence

What it does

Index of Coincidence (IC) is the probability of two randomly selected characters being the same. This can be used to determine whether text is readable or random, with English text having an IC of around 0.066. IC can therefore be a sound method to automate frequency analysis.

Note

Status here means the operation name is implemented and callable. It does not by itself promise byte-for-byte parity for every upstream option. See Compatibility and current status for the verified scope and known boundaries.

Arguments and options

This operation takes no positional recipe arguments.

Recipe template

Important

This is a call template built from the documented defaults. Replace placeholder values such as empty keys, paths, patterns, or lookup data before running it.

from pychef import bake

input_value = "example"
args = []
result = bake(input_value, ['Index of Coincidence'])
print(result)

Pipeline example

from pychef import Pipeline

args = []
transform = Pipeline().then('Index of Coincidence')
result = transform("example")

Direct call

pychef.ops.run_operation runs any registered operation as a plain function, under the active ExecutionPolicy (safe defaults, no network):

from pychef.ops import run_operation

args = []
result = run_operation('Index of Coincidence', "example", args=args)

Common operations also have typed helpers in Direct operations.

Low-level operation module

Warning

The module below is an internal implementation detail. It applies no execution policy, resource limits, or error sanitization; prefer bake(), Pipeline, or pychef.ops for application code.

The registered entry point lives in pychef.operations.by_operation.index_of_coincidence. Direct calls receive the input value and a positional argument tuple:

from pychef.operations.by_operation.index_of_coincidence import run

result = run("example", tuple([]))

pychef.operations.by_operation.index_of_coincidence.run(value, args)

Run this operation using its shared internal implementation.

Parameters:

value (str | bytes)
args (Sequence[Any])

Return type:

str | bytes