Vigenere Breaker

VigenereBreaker.js

"use strict";

function getIncidenceOfCoincidence(sequence) {
	
	// Get frequency
	let frequencyTable = {};

	for (let letter of sequence) {
		if (!frequencyTable.hasOwnProperty(letter)) {
			frequencyTable[letter] = 1;
		} else {
			frequencyTable[letter]++;
		}
	}

	let sum = 0;

	// Go Over frequency table
	for (let frequencyKey in frequencyTable) {
		if (frequencyTable.hasOwnProperty(frequencyKey)) {

			let lambda = frequencyTable[frequencyKey];

			// Get frequency Sum
			sum += (Math.pow(lambda, 2) - lambda);

		}
	}

	let stringLength = sequence.length;

	return (sum / (Math.pow(stringLength, 2) - stringLength));

};


(() => {

	const vigereneString = "afcusooqbqgywvohgqiunuwvalvzoooqpngeyshqhkzmnwvsebuwvwptbquwcwabojzeuhbpdmldhhavtwvqjjbxbzimnqresifssniqgwszpwflhebmywhdwbzbgajarvkanmyhorevtpspdmfhbpavphhdalehozomawsjymbirawbuzoopprooopwsgwopqafhwykrqhqwbvrbsdqpkfawkuhriumnugwbbruhdwbgksokcagcbpprlbmqqflhknqnojkekrvgaaurgaanorgwjkvrgfawullbzabruaejighvqiqgfcjrmlhrpkulvcqhbuhwzaibifarwyxhekvchfdwxfifkiqgvooowplopewalbbwvpbkeppgksxqzertwiqyokdamy";
	const vigereneStringLength = vigereneString.length;
	const lengthMax = 10;

	let results = {};

	for (let length = 2; length < lengthMax; length++) {

		// Initialise the object for length 2
		results[length] = {};

		let lengthCounter = 1;

		while ((lengthCounter + 1) <= length) {
			results[length][lengthCounter] = [];
			lengthCounter++
		}

		lengthCounter = 1;

		// Iterate over the string
		for (let vigerenePosition = 0; vigerenePosition < vigereneStringLength; vigerenePosition++) {
			
			// Reset
			if (lengthCounter == length) {
				lengthCounter = 1;
			}

			// Store
			results[length][lengthCounter].push(vigereneString[vigerenePosition])

			// Increase length
			lengthCounter++;

		}

	}

	// Print out
	for (let resultKey in results) {
		if (results.hasOwnProperty(resultKey)) {

			console.log(`Result Key: ${resultKey - 1}`);

			let sequence = results[resultKey];

			for (let sequenceKey in sequence) {
				if (sequence.hasOwnProperty(sequenceKey)) {
					
					// Print Sequence
					console.log(`Sequence ${sequenceKey}: ` + sequence[sequenceKey]);

					// Get IC of each Sequence
					let incidenceOfCoincidence = getIncidenceOfCoincidence(sequence[sequenceKey]);
					console.log(`IC ${sequenceKey}: ${incidenceOfCoincidence}`);

				}
			}

			console.log("\n");

		}
	}

})();