An SSL session is started by a handshake procedure that involves multiple round trips (see the following figure). The client and server have to exchange four messages with a latency of around 50 milliseconds each. In total, we have at least 200 milliseconds of overhead while establishing a secure connection. In addition to that, both the client and the server need to perform public-key cryptographic operations in order to share a common secret. These operations are computationally expensive.

Normal SSL handshake

The client can request an abbreviated handshake in effect (see the following figure), saving a full round-trip of 100 milliseconds and avoiding the most expensive part of the full SSL handshake:

Abbreviated handshake

The abbreviated handshake can be accomplished either through the session identifiers mechanism defined by RFC 5246, or through the session tickets mechanism detailed in RFC 5077.

To make abbreviated handshakes with session identifiers possible,...