How Does HTTPS Secure Your Web Traffic? A Deep Dive into HTTP vs HTTPS

Differences Between HTTP and HTTPS

Security: HTTPS adds TLS/SSL encryption, providing stronger protection than plain HTTP.

Certificate: HTTPS requires a certificate issued by a Certificate Authority (CA).

Transport: HTTP transmits data in clear text, while HTTPS encrypts the data with SSL/TLS.

Connection and Port: HTTP is stateless and uses port 80; HTTPS builds on HTTP with SSL encryption and uses port 443.

HTTP Workflow

HTTP follows a client‑server model where the client initiates a request and the server returns a response.

Domain name resolution is performed via DNS to obtain the server’s IP address.

The client assembles an HTTP request packet, including headers and optional body.

The request is encapsulated into a TCP segment and a TCP three‑way handshake establishes the connection.

The client sends the HTTP request command over the established TCP connection.

The server processes the request and sends back an HTTP response.

After responding, the server typically closes the TCP connection.

The client parses the response, interprets the HTML, and renders the page.

Principles of HTTPS Implementation

HTTP alone transmits data in plaintext and cannot guarantee confidentiality.

HTTPS augments HTTP with the SSL/TLS protocol to provide encryption.

Both SSL and TLS are used; SSL relies on digital certificates to authenticate the server and to encrypt the communication channel.

HTTPS Communication Process

When an HTTPS session starts, the client first establishes an SSL/TLS layer on top of the TCP connection. It sends the SSL/TLS version number and supported cipher suites to the server. The server selects a matching suite, returns its digital certificate (containing the public key, domain name, and issuing CA) and its private key information.

The client validates the server’s certificate against trusted CAs. Upon successful verification, the client uses asymmetric encryption (public‑key cryptography) to securely exchange a symmetric session key.

After the symmetric key is agreed upon, the client and server encrypt all subsequent HTTP traffic with this key. The rest of the data exchange follows the standard HTTP flow—TCP three‑way handshake, request/response exchange, and TCP four‑way termination—while the payload remains encrypted.

Step‑by‑Step HTTPS Handshake (Simplified)

Client and server establish a TCP connection.

Client sends an HTTPS request.

Server responds with a digital certificate that includes the public key, domain name, and issuing organization.

Client validates the certificate’s authenticity.

If the public key is valid, the client generates a symmetric key (client key) and encrypts it with the server’s public key.

Client sends the encrypted symmetric key as part of a second HTTP request.

Server decrypts the symmetric key with its private key, then uses it to encrypt data sent back to the client.

Client receives the encrypted data, decrypts it with the symmetric key, and renders the web page.