HTTPS Explained: TLS Handshake and Secure HTTP
HTTPS uses HTTP over TLS to protect communication between a client and a server. TLS provides confidentiality and integrity, and the client normally authenticates the server using its certificate.
Published by Protocol Explorer · Reviewed
Before the secure exchange
The client finds the server address and establishes a transport connection. For HTTPS over TCP, a TCP handshake precedes the TLS handshake. HTTP/3 instead uses QUIC, which integrates TLS with its transport.
TLS 1.3 handshake
The client sends a ClientHello describing supported options and key shares. The server responds with a ServerHello and other handshake messages. The client checks the certificate and handshake evidence, and the endpoints establish shared traffic keys.
HTTP inside TLS
After the handshake, HTTP messages travel as encrypted application data. An observer can see some network metadata and packet sizes, but cannot read protected HTTP content without the relevant keys. TLS does not guarantee that an authenticated website is trustworthy in every respect.
Read the sequence
In the explorer, follow TCP establishment, TLS negotiation and the HTTP request and response. The teaching scenario represents encrypted or random bytes as such; it is not a capture of your own traffic.
Follow an example step by step
- Resolve the server name and establish the transport used by the example.
- Follow the TLS handshake and check how the client authenticates the server certificate.
- After handshake completion, identify the encrypted application-data records that carry HTTP.
Common interpretation mistake
Do not expect to read HTTP paths or bodies from encrypted records without access to session keys.
Key point to remember
HTTPS protects traffic in transit; it does not establish that the content served by a validly authenticated site is safe.
Try the interactive lesson
Open Protocol Explorer and select HTTPS to follow the exchange packet by packet. The HTTPS lesson is free and does not require an account. Pro is a one-time $4.99 purchase for the full library; an account is required to buy and restore it.
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Primary reference
Related protocol lessons
TCP · UDP · HTTP · How to read a packet