Decrypt the Rails session cookie in Node.js

decrypt_session.js

function decrypt_session(cookie) {
    const SALT = "authenticated encrypted cookie";
    const secret = crypto.pbkdf2Sync(secret_key_base, SALT, 1000, 32, 'sha1');
    
    const [data, iv, auth_tag] = cookie.split('--').map(s => Buffer.from(s, 'base64'));
    const decipher = crypto.createDecipheriv('aes-256-gcm', secret, iv);
    decipher.setAuthTag(auth_tag);

    let decrypted_data = decipher.update(data);
    decrypted_data = Buffer.concat([decrypted_data, decipher.final()]);
    console.log(decrypted_data.toString());
}