Why HTTPS Matters: Performance, Security, and the Cryptography Behind It

Performance

HTTP has several issues, the most serious being performance. HTTP is built on TCP, and its headers cannot be compressed, leading to large data packets. Moreover, each connection supports only one request, making it slow.

HTTPS does not solve these performance problems; it adds an extra layer and can be slower due to encryption overhead. However, HTTPS enables HTTP/2, which improves speed through multiplexing, allowing multiple requests over a single connection.

Security

Users see a lock icon and assume safety, but HTTP has major security flaws. Data is transmitted in clear text, making it vulnerable to interception, eavesdropping on public Wi‑Fi, and injection of unwanted content by ISPs.

HTTP lacks confidentiality and authentication; attackers can read or modify traffic, and neither client nor server can verify each other's identity.

Cryptography Behind HTTPS

HTTPS addresses HTTP’s core issues using TLS, OpenSSL, and certificates. Symmetric encryption protects data with a shared secret, while asymmetric encryption (public‑key cryptography) handles key exchange, though it is slower and vulnerable to man‑in‑the‑middle attacks without proper verification.

Certificates issued by trusted CAs bind public keys to identities, enabling clients to trust the server’s key. The certificate itself is signed using asymmetric encryption, and its integrity is verified with hash algorithms.

For large payloads, symmetric encryption is used after the asymmetric handshake, and HMAC provides integrity checking.