AJAX - HTTPS and its role in securing AJAX communication.

1) What is HTTPS?

  • HTTPS (HyperText Transfer Protocol Secure) is HTTP over TLS/SSL.

  • It encrypts all communication between browser ↔ server, including AJAX requests.

  • Without HTTPS, AJAX calls send data in plain text, vulnerable to:

    • Eavesdropping (attackers read data).

    • Man-in-the-Middle (MITM) attacks (attackers alter responses).

2) Why HTTPS Matters for AJAX

AJAX often sends sensitive data:

  • Login credentials (username, password).

  • Authentication tokens (JWT, OAuth).

  • Personal information (emails, credit cards).

If sent over plain HTTP → anyone on the same network (e.g., Wi-Fi hotspot) can steal it.

With HTTPS:

  • Data is encrypted (attackers can’t read it).

  • Data is integrity-protected (attackers can’t change it unnoticed).

  • The server’s identity is verified with a certificate.

3) How HTTPS Secures AJAX

When you call an API with AJAX:

Example:

fetch("https://api.example.com/data", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({ msg: "Hello" })
})
.then(res => res.json())
.then(data => console.log(data));

What happens:

  1. Browser verifies the server’s TLS certificate.

  2. Browser and server perform a handshake → agree on encryption keys.

  3. AJAX request is encrypted before leaving the browser.

  4. Server decrypts, processes, and encrypts response back.

  5. Browser decrypts and delivers response to JavaScript.

4) Best Practices for HTTPS + AJAX

a) Always Use HTTPS

  • Never mix HTTP and HTTPS (called mixed content).

  • Browsers will block AJAX calls to HTTP if the page is served over HTTPS.

b) Use Secure Cookies for Sessions

Set-Cookie: session=abc123; Secure; HttpOnly; SameSite=Strict

  • Secure: Cookie only sent over HTTPS.

  • Prevents attackers from stealing session IDs over HTTP.

c) Protect Against Certificate Issues

  • Use valid TLS certificates (Let’s Encrypt, commercial CAs).

  • Don’t ignore browser certificate warnings.

  • Enable HSTS (HTTP Strict Transport Security) so browsers always use HTTPS.

d) Combine with Other Security Layers

  • CORS → controls who can call your API.

  • CSRF protection → prevents forged AJAX requests.

  • Authentication tokens or sessions → verify identity.

5) Example: Secure vs Insecure

Insecure (HTTP)

fetch("http://api.example.com/user"); // Data exposed!

Secure (HTTPS)

fetch("https://api.example.com/user", {
  headers: { "Authorization": "Bearer " + token }
});

6) Summary

  • HTTPS is mandatory for AJAX that handles sensitive data.

  • It protects against:

    • Eavesdropping

    • Tampering

    • Impersonation

  • Use with other protections (CORS, CSRF tokens, authentication) for full security.