Index of Coincidence Calculator
Statistical tool for cipher analysis to determine if text is encrypted and likely cipher type.
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Cipher DecipherText Tool
Index of Coincidence:
- Measures probability that two randomly selected characters are identical
- Higher IC indicates natural language or monoalphabetic cipher
- Lower IC suggests polyalphabetic cipher or random text
- Used to determine if text is encrypted and likely cipher type
Formula: IC = Σ(ni × (ni - 1)) / (N × (N - 1))
Where ni = count of letter i, N = total letters
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