Differences Between HTTP and HTTPS

Differences Between HTTP and HTTPS

Description
HTTP (Hypertext Transfer Protocol) and HTTPS (Hypertext Transfer Protocol Secure) are application-layer protocols used to transmit data between clients and servers. HTTPS is essentially the secure version of HTTP, protecting data transmission security through encryption and authentication mechanisms. Understanding the differences between the two helps in grasping the fundamental security principles of network communication.

Explanation

  1. Basic Characteristics of HTTP

    • HTTP is a plaintext protocol; data is not encrypted, and transmitted content (such as passwords, personal information) may be eavesdropped on or tampered with.
    • It uses port 80 by default, and the communication process lacks identity verification, making it vulnerable to man-in-the-middle attacks (e.g., impersonating a server).
    • Its advantages are simplicity and speed, making it suitable for transmitting non-sensitive information (such as static web page browsing).

  2. Security Mechanisms of HTTPS

    • HTTPS adds the TLS/SSL protocol (now mainly using TLS) below the HTTP layer, transmitting data through an encrypted channel.
    • Encryption Principle: Uses asymmetric encryption (e.g., RSA) to exchange keys during the handshake phase, followed by symmetric encryption (e.g., AES) to efficiently encrypt data.
    • Identity Verification: Relies on digital certificates (issued by trusted Certificate Authorities, CAs) to ensure the client accesses the genuine server.
    • It uses port 443 by default, and a TLS handshake (including certificate verification, key negotiation, etc.) must be completed before communication begins.

  3. Core Differences Comparison

    • Security: HTTPS prevents eavesdropping (encryption), tampering (integrity checks), and impersonation (certificate verification); HTTP provides no protection.
    • Performance: HTTPS incurs slightly higher overhead due to encryption calculations and handshake latency, but the gap has narrowed with modern hardware optimization.
    • SEO and Compliance: Search engines prioritize indexing HTTPS websites, and modern browsers mark non-HTTPS sites as "Not Secure."

Example Scenario
Assuming a user logs into a website:

  • If HTTP is used, the password is transmitted in plaintext, and hackers on the same Wi-Fi can intercept the data.
  • If HTTPS is used, the password is encrypted into unreadable code, making it impossible to decrypt even if intercepted, and the browser verifies the authenticity of the certificate.

Summary
HTTPS adds three layers of protection—encryption, integrity, and authentication—to HTTP through the TLS/SSL protocol, forming the cornerstone of modern web security. In practice, mainstream websites have already mandated HTTPS to protect user privacy.