From e7515ffa63c74078ec09298f5fdcc7277e1f1d98 Mon Sep 17 00:00:00 2001
From: Flavio Diez <flaviofdiez@gmail.com>
Date: Mon, 27 Jan 2020 15:02:39 +0100
Subject: [PATCH] Add Rail Fence Cipher Encode

---
 src/core/config/Categories.json               |  1 +
 src/core/operations/RailFenceCypherEncode.mjs | 96 +++++++++++++++++++
 2 files changed, 97 insertions(+)
 create mode 100644 src/core/operations/RailFenceCypherEncode.mjs

diff --git a/src/core/config/Categories.json b/src/core/config/Categories.json
index cc9268fc..0d68efe8 100755
--- a/src/core/config/Categories.json
+++ b/src/core/config/Categories.json
@@ -95,6 +95,7 @@
             "Affine Cipher Decode",
             "A1Z26 Cipher Encode",
             "A1Z26 Cipher Decode",
+            "Rail Fence Cipher Encode",
             "Rail Fence Cipher Decode",
             "Atbash Cipher",
             "Substitute",
diff --git a/src/core/operations/RailFenceCypherEncode.mjs b/src/core/operations/RailFenceCypherEncode.mjs
new file mode 100644
index 00000000..8da1830b
--- /dev/null
+++ b/src/core/operations/RailFenceCypherEncode.mjs
@@ -0,0 +1,96 @@
+/**
+ * @author Flavio Diez [flaviofdiez+cyberchef@gmail.com]
+ * @copyright Crown Copyright 2020
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation.mjs";
+
+/**
+ * Rail Fence Cypher Encode operation
+ */
+class RailFenceCypherEncode extends Operation {
+
+    /**
+     * RailFenceCypherEncode constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Rail Fence Cypher Encode";
+        this.module = "Ciphers";
+        this.description = "Encodes Strings using the Rail fence Cypher provided a key and an offset";
+        this.infoURL = "https://en.wikipedia.org/wiki/Rail_fence_cipher";
+        this.inputType = "string";
+        this.outputType = "string";
+        this.args = [
+            {
+                name: "Key",
+                type: "number",
+                value: 2
+            },
+            {
+                name: "Offset",
+                type: "number",
+                value: 0
+            }
+        ];
+    }
+
+    /**
+     * @param {string} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    run(input, args) {
+        const [key] = args;
+        // const [key, offset] = args;
+
+        const plaintext = input;
+
+        if (key < 2) {
+            return "Key has to be bigger than 2";
+        } else if (key > plaintext.length) {
+            return "Key should be smaller than the plain text's length";
+        }
+
+        let cipher = "";
+
+        for (let block = 0; block < key; block++) {
+            for (let pos = block; pos < plaintext.length; pos += key) {
+                cipher += plaintext[pos];
+            }
+        }
+
+        return cipher;
+    }
+
+    /**
+     * Highlight Rail Fence Cypher Encode
+     *
+     * @param {Object[]} pos
+     * @param {number} pos[].start
+     * @param {number} pos[].end
+     * @param {Object[]} args
+     * @returns {Object[]} pos
+     */
+    highlight(pos, args) {
+        return pos;
+    }
+
+    /**
+     * Highlight Rail Fence Cypher 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 RailFenceCypherEncode;