October 15, 2018

The Illustrated TLS Connection

Every byte of a TLS connection explained and reproduced.

In this demonstration, a client has connection to a server, negotiated a TLS 1.2 session, sent "ping", received "pong", and then terminated the session. Click below to begin exploring.

Client Hello

 

The session begins with the client saying "Hello". The client provides the following:
  • protocol version
  • client random data (used later in the handshake)
  • an optional session id to resume
  • a list of cipher suites
  • a list of compression methods
  • a list of extensions

Annotations16 03 01 00 a5 01 00 00 a1 03 03 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f 00 00 20 cc a8 cc a9 c0 2f c0 30 c0 2b c0 2c c0 13 c0 09 c0 14 c0 0a 00 9c 00 9d 00 2f 00 35 c0 12 00 0a01 00 00 58 00 00 00 18 00 16 00 00 13 65 78 61 6d 70 6c 65 2e 75 6c 66 68 65 69 6d 2e 6e 65 74 00 05 00 05 01 00 00 00 00 00 0a 00 0a 00 08 00 1d 00 17 00 18 00 19 00 0b 00 02 01 00 00 0d 00 12 00 10 04 01 04 03 05 01 05 03 06 01 06 03 02 01 02 03 ff 01 00 01 00 00 12 00 00

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