What is HTTPS?

  • Hypertext Transfer Protocol Secure: Secure version of HTTP for safe data transfer between browser and website.
  • Uses SSL/TLS to encrypt data, verify website identity, and ensure data integrity.

How HTTPS Works (Step-by-Step)

  1. Starting the Connection

    • Enter https://example.com → Browser connects to website’s server (port 443).
    • "S" in HTTPS means secure, using encryption.

  2. SSL/TLS Handshake (Setting Up Security)

    • Server sends certificate: Contains server’s public key and identity info.
    • Browser verifies certificate: Checks if it’s valid, not expired, and from a trusted Certificate Authority (CA) (e.g., Let’s Encrypt).
    • Session key creation: Browser creates a random session key, encrypts it with server’s public key, and sends it.
    • Server decrypts: Uses its private key to get the session key.
    • Result: Both now share a secret session key for fast, symmetric encryption.

  3. Secure Data Transfer

    • Browser and server use the session key to encrypt/decrypt data (e.g., passwords, web pages).
    • Data is unreadable to eavesdroppers (e.g., hackers on public Wi-Fi).
    • Integrity check: Hashing ensures data isn’t tampered with during transfer.

  4. Ongoing Communication

    • Secure exchange continues until you leave the site.
    • Each session gets a new session key for security.

Key Concepts to Remember

  • SSL/TLS:

    • SSL (Secure Sockets Layer): Old protocol, replaced by TLS (Transport Layer Security).
    • Provides:
      • Encryption: Scrambles data so only intended recipient can read it.
      • Authentication: Verifies website is legit (not a fake).
      • Integrity: Ensures data isn’t altered in transit.

  • Certificates:

    • Issued by CAs to prove website identity.
    • Contains public key and domain details.
    • Browser trusts CAs to confirm site is genuine.

  • Encryption Types:

    • Asymmetric: Uses public/private key pair for handshake (slower, secure for key exchange).
    • Symmetric: Uses shared session key for faster data transfer.

  • Why HTTPS Matters:

    • Protects sensitive info (e.g., logins, credit cards).
    • Prevents man-in-the-middle attacks (someone intercepting data).
    • Builds trust: Browsers warn “Not Secure” for non-HTTPS sites.
    • Boosts website SEO.

Memory Aids

  • HTTPS = HTTP + Security: Think “S” for “Safe.”
  • Handshake = Trust Setup: Like exchanging a secret code before talking.
  • Certificate = Website ID: Like a driver’s license for a website.
  • Session Key = Secret Handshake: A temporary code only you and the server know.
  • Encryption = Scrambling: Turns your data into gibberish without the key.

Example to Visualize

  • You visit https://yourbank.com:
    1. Browser asks server for a secure connection.
    2. Server shows its “ID card” (certificate).
    3. Browser checks ID with a trusted authority (CA).
    4. You and server agree on a secret code (session key).
    5. All data (e.g., your login) is sent scrambled, safe from hackers.