Cryptographic Protocols - Codes: The Guide to Secrecy from Ancient to Modern Times - page 221

We begin bydescribing the lower level of SSL.

SSL Record Protocol
This protocol defines the format used to transmit data, and is used bythe
handshake protocol to exchange messages between client and server. First the
message to be transmitted is fragmented , which means it breaks the message
down into manageable blocks. Then it compresses the data (but this is an
optional exercise in SSL). It then applies a MAC (see page 136), enciphers the
data, adds a header, and transmits the cryptogram as a TCP unit. This is
illustrated in Diagram 5.2.

Diagram 5.2 SSL Record Protocol Actions

Message Data

Fragment Fragment ··· Fragment Fragment

✞
✝ ✆

Compress

Compressed Data Add MAC

Encipher

Add Header

Cryptogram

Transmit

Upon receipt of the transmitted data, it is deciphered, authenticated, de-
compressed, reassembled, and delivered to users at higher levels.