Understanding HTTPS: Principles, Encryption, and Security

In recent years, HTTPS has become increasingly popular as users and internet companies raise security awareness and the cost of HTTPS drops; major browsers and platforms such as Google Chrome, WeChat mini‑programs, and Apple App Store now require HTTPS for all sites and apps.

HTTP’s biggest drawback is its lack of security: data is transmitted in clear text, exposing sensitive information like passwords and credit‑card numbers to eavesdropping.

Using simple front‑end hashing (e.g., MD5) does not solve the problem because MD5 is a one‑way hash, not an encryption algorithm, and the hashed value can still be intercepted and misused.

True encryption is needed. Symmetric encryption (e.g., DES, 3DES, AES) uses the same secret key for encryption and decryption, offering fast processing and high efficiency, but it suffers from key‑distribution challenges and scalability issues.

Asymmetric encryption uses a pair of keys—a public key and a private key. RSA is the most common algorithm, providing high security because the private key never travels over the network, though it is computationally intensive.

Combining both methods solves the key‑exchange problem: the client obtains the server’s public key from its certificate, generates a random symmetric key (KEY), encrypts KEY with the public key, and sends it to the server; the server decrypts KEY with its private key, establishing a shared secret for fast symmetric encryption of subsequent data.

HTTPS therefore equals HTTP plus TLS/SSL. The handshake involves certificate verification and two encryption phases: (1) the client connects to the server’s port 443, (2) the server presents a CA‑signed certificate containing its public key, (3) the client validates the certificate, (4) the client generates a random KEY and encrypts it with the server’s public key, (5) the server decrypts KEY with its private key, (6) both sides use KEY for symmetric encryption of all subsequent traffic.

The article concludes with a comparison: HTTPS provides confidentiality, integrity, and authentication at the cost of higher latency, greater server resource consumption, the need for paid certificates, and potential vulnerability to certain attacks such as man‑in‑the‑middle under compromised certificates.

Overall, HTTPS replaces HTTP by adding TLS/SSL encryption, ensuring secure communication for modern web applications.