Merge 27c9330b9f into 1b8c229df2

vigenere.js

@@ -0,0 +1,88 @@
+function cleanText(text) {
+    const textNoSpaces = text.replace(/ /g, "");
+    if (/[^A-Za-z0-9]/.test(textNoSpaces)) {
+        throw new Error("Special characters detected. They must be removed.");
+    }
+    return textNoSpaces;
+}
+
+function encrypt(message, key) {
+    message = message.toLowerCase();
+    key = key.toLowerCase();
+    const combinedAlphabet = "abcdefghijklmnopqrstuvwxyz0123456789";
+    const n = combinedAlphabet.length;
+    const encrypted = [];
+    let keyIndex = 0;
+
+    try {
+        for (const char of message) {
+            if (combinedAlphabet.includes(char)) {
+                const mIndex = combinedAlphabet.indexOf(char);
+                const keyChar = key[keyIndex % key.length];
+                const shift = combinedAlphabet.indexOf(keyChar);
+                const newIndex = (mIndex + shift) % n;
+                encrypted.push(combinedAlphabet[newIndex]);
+                keyIndex++;
+            }
+        }
+        return encrypted.join("");
+    } catch (e) {
+        throw new Error("Encryption error: " + e.message);
+    }
+}
+
+function decrypt(cipherText, key) {
+    cipherText = cipherText.toLowerCase();
+    key = key.toLowerCase();
+    const combinedAlphabet = "abcdefghijklmnopqrstuvwxyz0123456789";
+    const n = combinedAlphabet.length;
+    const decrypted = [];
+    let keyIndex = 0;
+
+    try {
+        for (const char of cipherText) {
+            if (combinedAlphabet.includes(char)) {
+                const cIndex = combinedAlphabet.indexOf(char);
+                const keyChar = key[keyIndex % key.length];
+                const shift = combinedAlphabet.indexOf(keyChar);
+                const originalIndex = (cIndex - shift + n) % n;
+                decrypted.push(combinedAlphabet[originalIndex]);
+                keyIndex++;
+            }
+        }
+        return decrypted.join("");
+    } catch (e) {
+        throw new Error("Decryption error: " + e.message);
+    }
+}
+
+function main() {
+    try {
+        const rawMessage = prompt("Enter the message: ");
+        const rawKey = prompt("Enter the key: ");
+        try {
+            const cleanedMessage = cleanText(rawMessage);
+            const cleanedKey = cleanText(rawKey);
+            if (!cleanedMessage) {
+                throw new Error("Message is empty after cleaning!");
+            }
+            if (!cleanedKey) {
+                throw new Error("Key is empty after cleaning!");
+            }
+            const encryptedMsg = encrypt(cleanedMessage, cleanedKey);
+            console.log("\nEncrypted Message:");
+            console.log(encryptedMsg);
+            const decryptedMsg = decrypt(encryptedMsg, cleanedKey);
+            console.log("\nDecrypted Message:");
+            console.log(decryptedMsg);
+        } catch (ve) {
+            console.log("Input error:", ve.message);
+            return;
+        }
+    } catch (e) {
+        console.log("An error occurred:", e.message);
+    }
+}
+
+main();
+