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User Authentication & Authorization

MeetMate implements a robust and secure authentication and authorization system to ensure the protection of user data and control access to various application features and resources.

Authentication

User Registration and Login

MeetMate supports credential-based authentication. During registration, users provide their name, email, and password on the signup page. Upon successful registration, their information is securely stored in a PostgreSQL database, with passwords hashed using a secure hashing algorithm from the spring boot security library.

Example registration process:

// --- Frontend (NextJS Server Component) --- //
const handleRegistration = async (name, email, password) => {
    // [... validate input fields ...]
    const response = await fetch(process.env.BACKEND_DOMAIN + "/api/user/signup", {
        method: "POST",
        headers: {
            "Content-Type": "application/x-www-form-urlencoded;charset=UTF-8"
        },
        body: encodedData
    });
    if (response.ok) {
        return { // Handle successful registration
            message: "success",
            errors: undefined,
            fieldValues: { name: "", email: "", password: "", confirmPassword: "" }
        };
    } else if (response.status === 409) {
        return { // Handle email duplication error (specific errors)
            message: "error",
            errors: {
                name: undefined!,
                email: "This email is already taken",
                password: undefined!,
                confirmPassword: undefined!
            },
            fieldValues: { name, email, password, confirmPassword }
        }; // [... other error handling ...]
    } else {
        return { // Handle other errors
            message: "error",
            errors: { name: "", email: "", password: "", confirmPassword: "" },
            fieldValues: { name, email, password, confirmPassword }
        };
    }
}
// --- Backend (Spring Boot Controller) --- //
@PostMapping(path = "signup")
@ResponseBody
public ResponseEntity<?> registerNewUser(@RequestParam MultiValueMap<String, String> data) {
    try {
        userService.registerNewUser(data);
        return ResponseEntity.ok().build();
    } catch (Throwable t) {
        // [...]
        if (tc == IllegalArgumentException.class)
            return ResponseEntity.status(HttpStatus.NOT_ACCEPTABLE).body("message: " + t.getMessage());

        if (tc == NameAlreadyBoundException.class)
            return ResponseEntity.status(HttpStatus.CONFLICT)
                    .body("message: " + t.getMessage());

        return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR)
                .body("message: " + t.getMessage());
    }
}
For login, users navigate to the login page and enter their email and password credentials. The application validates these credentials against the stored data in the database by comparing the provided password with the hashed password.

Session Management

Upon successful authentication, MeetMate generates JSON Web Tokens (JWTs) for session management. An access token and a refresh token are created and stored as HttpOnly cookies on the client-side. The access token is used for authenticating subsequent requests to the backend, while the refresh token is used to obtain a new access token when the current one expires.

Example token generation and verification:

// --- Backend (Spring Boot Service) --- //
public String generateAccessToken(User user) throws EntityNotFoundException {
    if (user == null) throw new EntityNotFoundException("No user specified");
    return Jwts.builder()
        .setClaims(user.generateMap())
        .setSubject(user.getEmail())
        .setIssuedAt(new Date(System.currentTimeMillis()))
        .setExpiration(new Date(System.currentTimeMillis() + 1000 * 60 * 5)) // expires in 5 minutes
        .signWith(getSigningKey(), SignatureAlgorithm.HS256)
        .compact();
}
// --- Middleware (NextJS) --- //
// If no user, try to refresh the access token using a valid refresh token.
if (user === null) {
    console.log("No user found, attempting to refresh access token.");
    const refreshToken = req.cookies.get("refreshToken")?.value;
    if (refreshToken !== undefined || refreshToken !== "") {
        const newAccessToken = await refreshAccessToken(refreshToken);
        if (newAccessToken !== undefined) {
            response.cookies.set("accessToken", newAccessToken[0], { httpOnly: true, secure: true, sameSite: "strict" });
            response.cookies.set("expires_at", newAccessToken[1], { httpOnly: true, secure: true, sameSite: "strict" });
            user = await getUser(newAccessToken[0]);
            if (user === null) {
                return NextResponse.redirect(new URL("/login", req.url));
            }
        } else {
            console.log("Error refreshing access token, redirecting to login.");
            return NextResponse.redirect(new URL("/login", req.url));
        }
    } else {
        console.log("No refresh token found, redirecting to login.");
        return NextResponse.redirect(new URL("/login", req.url));
    }
}

The frontend sends requests to the backend along with the valid access token to retrieve the user's information and render content accordingly.

Authorization

MeetMate employs a middleware layer to handle authentication and authorization, controlling access to specific routes and pages based on the user's role and permissions.

When accessing a protected route or page, the application sends a request to the backend to obtain the user's role information. Based on this role, the frontend dynamically renders or restricts access to certain features and content.

Example authorization middleware and role-based rendering:

// Frontend (NextJS Page Component)
const AdminDashboard = () => {
    const [userRole, setUserRole] = useState("");

    useEffect(() => {
        const fetchUser = async () => {
            try {
                const accessToken = await getAccessToken();
                setUser(await getUser(accessToken));
            } catch (error) {
                console.error("Failed to fetch user", error);
            }
        };
        fetchUser().catch(console.error);
    }, []);

    return (
        <div>
            {user?.role === "ADMIN" && <AdminContent />}
            {/* Render user dashboard content */}
        </div>
    );
};

Security Measures

Password Hashing

MeetMate implements industry-standard password hashing techniques to securely store user passwords in the database. This ensures that even in the event of a data breach, the actual passwords remain protected, and only the hashed values are stored.

Rate Limiting

To mitigate brute-force attacks and excessive failed login attempts, the backend incorporates rate-limiting mechanisms using a completely custom-made system. This helps to prevent unauthorized access and potential security breaches by limiting the number of requests from a specific IP address or user within a certain time frame.

Example rate-limiting implementation:

private final HashMap<String, LinkedList<Long>> requests = new HashMap<>();
private final int maxRequests = 5;
private final long refreshTime = 1000 * 10; // 10 seconds

@Override
protected void doFilterInternal(@NotNull HttpServletRequest request, @NotNull HttpServletResponse response, @NotNull FilterChain filterChain) throws ServletException, IOException {
    String ip = request.getRemoteAddr();

    if (requests.containsKey(ip))
        requests.get(ip).addLast(System.currentTimeMillis());
    else
        requests.put(ip, new LinkedList<Long>(Collections.singleton(System.currentTimeMillis())));

    if (requests.get(ip).size() > maxRequests) {
        response.setStatus(429);
        response.getWriter().write("Too many requests");
        return;
    }

    filterChain.doFilter(request, response);
}

Error Handling

The frontend application has a robust error handling system in place to prevent unnecessary requests and provide appropriate feedback to users in case of authentication or authorization errors. This may involve displaying user-friendly error messages, redirecting to appropriate pages, or implementing retry mechanisms.

Session Termination

When a user logs out of the application, the JWT tokens stored as HttpOnly cookies on the client-side are deleted, effectively terminating the user's session. This can be achieved by simply removing the cookies from the client-side storage.

Future Enhancements

MeetMate plans to introduce additional authentication methods, such as social logins (e.g., Google, GitHub), to provide users with a faster and more convenient signup process. This feature will be implemented while maintaining the highest standards of security and data protection.

Additionally, MeetMate may consider implementing advanced security features like two-factor authentication (2FA) for enhanced security and user verification.