vignere-babbage-cipher/lib/index.js

Encrypt/decrypt by using the Vignere–Babbage cipher

"use strict";

// Key:        C O D E H E L L O W (x)
// Encrypted:  J S O P V A Z C Z Z (from the table)
// Plain text: H E L L O W O R L D (Y)

var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

var VIGNERE_SQUARE = {
    A: "ABCDEFGHIJKLMNOPQRSTUVWXYZ",
    B: "BCDEFGHIJKLMNOPQRSTUVWXYZA",
    C: "CDEFGHIJKLMNOPQRSTUVWXYZAB",
    D: "DEFGHIJKLMNOPQRSTUVWXYZABC",
    E: "EFGHIJKLMNOPQRSTUVWXYZABCD",
    F: "FGHIJKLMNOPQRSTUVWXYZABCDE",
    G: "GHIJKLMNOPQRSTUVWXYZABCDEF",
    H: "HIJKLMNOPQRSTUVWXYZABCDEFG",
    I: "IJKLMNOPQRSTUVWXYZABCDEFGH",
    J: "JKLMNOPQRSTUVWXYZABCDEFGHI",
    K: "KLMNOPQRSTUVWXYZABCDEFGHIJ",
    L: "LMNOPQRSTUVWXYZABCDEFGHIJK",
    M: "MNOPQRSTUVWXYZABCDEFGHIJKL",
    N: "NOPQRSTUVWXYZABCDEFGHIJKLM",
    O: "OPQRSTUVWXYZABCDEFGHIJKLMN",
    P: "PQRSTUVWXYZABCDEFGHIJKLMNO",
    Q: "QRSTUVWXYZABCDEFGHIJKLMNOP",
    R: "RSTUVWXYZABCDEFGHIJKLMNOPQ",
    S: "STUVWXYZABCDEFGHIJKLMNOPQR",
    T: "TUVWXYZABCDEFGHIJKLMNOPQRS",
    U: "UVWXYZABCDEFGHIJKLMNOPQRST",
    V: "VWXYZABCDEFGHIJKLMNOPQRSTU",
    W: "WXYZABCDEFGHIJKLMNOPQRSTUV",
    X: "XYZABCDEFGHIJKLMNOPQRSTUVW",
    Y: "YZABCDEFGHIJKLMNOPQRSTUVWX",
    Z: "ZABCDEFGHIJKLMNOPQRSTUVWXY"
};

var VignereBabbageCipher = function () {
    function VignereBabbageCipher() {
        _classCallCheck(this, VignereBabbageCipher);
    }

    _createClass(VignereBabbageCipher, null, [{
        key: "encrypt",

        /**
         * encrypt
         * Encrypt the plain text.
         *
         * @name encrypt
         * @function
         * @static
         * @param {String} input The plain text to encrypt.
         * @param {String} key The key.
         * @returns {String} The encrypted version.
         */
        value: function encrypt(input, key) {
            var decrypted = "";
            if (input.length > key.length) {
                key += input.slice(0, input.length - key.length);
            }

            input = input.toUpperCase();
            key = key.toUpperCase();

            key = key.replace(new RegExp("[^" + VIGNERE_SQUARE.A + "]", "g"), "");
            var index = -1;
            return input.split("").map(function (letter) {
                var charset = VIGNERE_SQUARE[letter];
                if (charset) {
                    return charset[VIGNERE_SQUARE.A.indexOf(key[++index])];
                } else {
                    return letter;
                }
            }).join("");
        }

        /**
         * decrypt
         * Decrypt the input.
         *
         * @name decrypt
         * @function
         * @static
         * @param {String} input Decrypt the encrypted text.
         * @param {String} key The key.
         * @returns {String} The result in plain text.
         */

    }, {
        key: "decrypt",
        value: function decrypt(input, key) {
            var decrypted = "";

            input = input.toUpperCase();
            key = key.toUpperCase();

            var index = 0;
            return input.split("").map(function (letter) {
                var charset = VIGNERE_SQUARE[key[index]];
                if (!VIGNERE_SQUARE[letter]) {
                    return letter;
                }
                var cLetter = VIGNERE_SQUARE.A[charset.indexOf(letter)];
                key += cLetter;
                ++index;
                return cLetter;
            }).join("");
        }
    }]);

    return VignereBabbageCipher;
}();

module.exports = VignereBabbageCipher;