script.js

function caesarCipher(str, shift) {
    return str.split('').map(char => {
        if (char.match(/[a-z]/i)) {
            let code = char.charCodeAt();

            if ((code >= 65) && (code <= 90))
                return String.fromCharCode(((code - 65 + shift) % 26) + 65);

            else if ((code >= 97) && (code <= 122))
                return String.fromCharCode(((code - 97 + shift) % 26) + 97);
        }
        return char;
    }).join('');
}

function vigenereCipher(text, key) {
    let output = '';
    key = key.toUpperCase();

    for (let i = 0, j = 0; i < text.length; i++) {
        let c = text.charAt(i);

        if (c.match(/[a-z]/i)) {
            let code = text.charCodeAt(i);
            if ((code >= 65) && (code <= 90))
                c = String.fromCharCode(((code - 65 + key.charCodeAt(j % key.length) - 65) % 26) + 65);
            else if ((code >= 97) && (code <= 122))
                c = String.fromCharCode(((code - 97 + key.charCodeAt(j % key.length) - 65) % 26) + 97);

            j++;
        }
        output += c;
    }
    return output;
}

function encryptText() {
    const inputText = document.getElementById('inputText').value;
    const method = document.getElementById('encryptionMethod').value;
    let encryptedText = '';

    if (method === 'caesar') {
        const shift = 3; // You can customize the shift value
        encryptedText = caesarCipher(inputText, shift);
    } else if (method === 'vigenere') {
        const key = 'KEY'; // You can customize the key
        encryptedText = vigenereCipher(inputText, key);
    } else if (method === 'aes') {
        // AES encryption will require more complex setup, usually handled server-side
        encryptedText = 'AES Encryption is more complex and is usually done on the server-side.';
    }

    document.getElementById('outputText').value = encryptedText;
}