Converted Affine/Atbash operations to mjs & added tests

src/core/lib/Ciphers.mjs

@@ -0,0 +1,41 @@
+/**
+ * Cipher functions.
+ *
+ * @author Matt C [matt@artemisbot.uk]
+ * @copyright Crown Copyright 2018
+ * @license Apache-2.0
+ *
+ */
+
+/**
+ * Affine Cipher Encode operation.
+ *
+ * @author Matt C [matt@artemisbot.uk]
+ * @param {string} input
+ * @param {Object[]} args
+ * @returns {string}
+ */
+export function affineEncode(input, args) {
+    const alphabet = "abcdefghijklmnopqrstuvwxyz",
+        a = args[0],
+        b = args[1];
+    let output = "";
+
+    if (!/^\+?(0|[1-9]\d*)$/.test(a) || !/^\+?(0|[1-9]\d*)$/.test(b)) {
+        return "The values of a and b can only be integers.";
+    }
+
+    for (let i = 0; i < input.length; i++) {
+        if (alphabet.indexOf(input[i]) >= 0) {
+            // Uses the affine function ax+b % m = y (where m is length of the alphabet)
+            output += alphabet[((a * alphabet.indexOf(input[i])) + b) % 26];
+        } else if (alphabet.indexOf(input[i].toLowerCase()) >= 0) {
+            // Same as above, accounting for uppercase
+            output += alphabet[((a * alphabet.indexOf(input[i].toLowerCase())) + b) % 26].toUpperCase();
+        } else {
+            // Non-alphabetic characters
+            output += input[i];
+        }
+    }
+    return output;
+}

src/core/operations/AffineCipherDecode.mjs

@@ -0,0 +1,103 @@
+/**
+ * @author Matt C [matt@artemisbot.uk]
+ * @copyright Crown Copyright 2018
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation";
+import Utils from "../Utils";
+
+/**
+ * Affine Cipher Decode operation
+ */
+class AffineCipherDecode extends Operation {
+
+    /**
+     * AffineCipherDecode constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Affine Cipher Decode";
+        this.module = "Ciphers";
+        this.description = "The Affine cipher is a type of monoalphabetic substitution cipher. To decrypt, each letter in an alphabet is mapped to its numeric equivalent, decrypted by a mathematical function, and converted back to a letter.";
+        this.inputType = "string";
+        this.outputType = "string";
+        this.args = [
+            {
+                "name": "a",
+                "type": "number",
+                "value": 1
+            },
+            {
+                "name": "b",
+                "type": "number",
+                "value": 0
+            }
+        ];
+    }
+
+    /**
+     * @param {string} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    run(input, args) {
+        const alphabet = "abcdefghijklmnopqrstuvwxyz",
+            a = args[0],
+            b = args[1],
+            aModInv = Utils.modInv(a, 26); // Calculates modular inverse of a
+        let output = "";
+
+        if (!/^\+?(0|[1-9]\d*)$/.test(a) || !/^\+?(0|[1-9]\d*)$/.test(b)) {
+            return "The values of a and b can only be integers.";
+        }
+
+        if (Utils.gcd(a, 26) !== 1) {
+            return "The value of a must be coprime to 26.";
+        }
+
+        for (let i = 0; i < input.length; i++) {
+            if (alphabet.indexOf(input[i]) >= 0) {
+                // Uses the affine decode function (y-b * A') % m = x (where m is length of the alphabet and A' is modular inverse)
+                output += alphabet[Utils.mod((alphabet.indexOf(input[i]) - b) * aModInv, 26)];
+            } else if (alphabet.indexOf(input[i].toLowerCase()) >= 0) {
+                // Same as above, accounting for uppercase
+                output += alphabet[Utils.mod((alphabet.indexOf(input[i].toLowerCase()) - b) * aModInv, 26)].toUpperCase();
+            } else {
+                // Non-alphabetic characters
+                output += input[i];
+            }
+        }
+        return output;
+    }
+
+    /**
+     * Highlight Affine Cipher Decode
+     *
+     * @param {Object[]} pos
+     * @param {number} pos[].start
+     * @param {number} pos[].end
+     * @param {Object[]} args
+     * @returns {Object[]} pos
+     */
+    highlight(pos, args) {
+        return pos;
+    }
+
+    /**
+     * Highlight Affine Cipher Decode in reverse
+     *
+     * @param {Object[]} pos
+     * @param {number} pos[].start
+     * @param {number} pos[].end
+     * @param {Object[]} args
+     * @returns {Object[]} pos
+     */
+    highlightReverse(pos, args) {
+        return pos;
+    }
+
+}
+
+export default AffineCipherDecode;

src/core/operations/AffineCipherEncode.mjs

@@ -0,0 +1,76 @@
+/**
+ * @author Matt C [matt@artemisbot.uk]
+ * @copyright Crown Copyright 2018
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation";
+import { affineEncode } from "../lib/Ciphers";
+/**
+ * Affine Cipher Encode operation
+ */
+class AffineCipherEncode extends Operation {
+
+    /**
+     * AffineCipherEncode constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Affine Cipher Encode";
+        this.module = "Ciphers";
+        this.description = "The Affine cipher is a type of monoalphabetic substitution cipher, wherein each letter in an alphabet is mapped to its numeric equivalent, encrypted using simple mathematical function, <code>(ax + b) % 26</code>, and converted back to a letter.";
+        this.inputType = "string";
+        this.outputType = "string";
+        this.args = [
+            {
+                "name": "a",
+                "type": "number",
+                "value": 1
+            },
+            {
+                "name": "b",
+                "type": "number",
+                "value": 0
+            }
+        ];
+    }
+
+    /**
+     * @param {string} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    run(input, args) {
+        return affineEncode(input, args);
+    }
+
+    /**
+     * Highlight Affine Cipher Encode
+     *
+     * @param {Object[]} pos
+     * @param {number} pos[].start
+     * @param {number} pos[].end
+     * @param {Object[]} args
+     * @returns {Object[]} pos
+     */
+    highlight(pos, args) {
+        return pos;
+    }
+
+    /**
+     * Highlight Affine Cipher Encode in reverse
+     *
+     * @param {Object[]} pos
+     * @param {number} pos[].start
+     * @param {number} pos[].end
+     * @param {Object[]} args
+     * @returns {Object[]} pos
+     */
+    highlightReverse(pos, args) {
+        return pos;
+    }
+
+}
+
+export default AffineCipherEncode;

src/core/operations/AtbashCipher.mjs

@@ -0,0 +1,66 @@
+/**
+ * @author Matt C [matt@artemisbot.uk]
+ * @copyright Crown Copyright 2016
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation";
+import { affineEncode } from "../lib/Ciphers";
+
+/**
+ * Atbash Cipher operation
+ */
+class AtbashCipher extends Operation {
+
+    /**
+     * AtbashCipher constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Atbash Cipher";
+        this.module = "Ciphers";
+        this.description = "Atbash is a mono-alphabetic substitution cipher originally used to encode the Hebrew alphabet. It has been modified here for use with the Latin alphabet.";
+        this.inputType = "string";
+        this.outputType = "string";
+        this.args = [];
+    }
+
+    /**
+     * @param {string} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    run(input, args) {
+        return affineEncode(input, [25, 25]);
+    }
+
+    /**
+     * Highlight Atbash Cipher
+     *
+     * @param {Object[]} pos
+     * @param {number} pos[].start
+     * @param {number} pos[].end
+     * @param {Object[]} args
+     * @returns {Object[]} pos
+     */
+    highlight(pos, args) {
+        return pos;
+    }
+
+    /**
+     * Highlight Atbash Cipher in reverse
+     *
+     * @param {Object[]} pos
+     * @param {number} pos[].start
+     * @param {number} pos[].end
+     * @param {Object[]} args
+     * @returns {Object[]} pos
+     */
+    highlightReverse(pos, args) {
+        return pos;
+    }
+
+}
+
+export default AtbashCipher;