Transport Layer Security (TLS) handshakes often include fairly static information@ such as the server certificate and a list of trusted certification authorities (CAs). This information can be of considerable size@ particularly if the server certificate is bundled with a complete certificate chain (i.e.@ the certificates of intermediate CAs up to the root CA). This document defines an extension that allows a TLS client to inform a server of cached information@ thereby enabling the server to omit already available information.