TCP/IP Tutorial and Technical Overview - IBM Redbooks

► SEC-Exchange: Performs public key authentication or key exchange with a
client. Additional information about public keys is in OMA specifications
WAP-217-WPKI-20010424-a, WAP-217_103-WPKI-20011102-a, and
WAP-217_105-WPKI-20020816-a.
► SEC-Commit: Initiated when the handshake is completed and either peer
requests to switch to the agreed connection state.
► SEC-Terminate: Terminates the connection.
► SEC-Exception: Informs the other partner about warning level alerts.
► SEC-Create-Request: The server requests the client to initiate a new
handshake.
Protocol overview
As shown in Figure 18-21 on page 697, WTLS consists of four protocol
components:
► The record protocol
► The handshake protocol
► The alert protocol
► The change CipherSpec protocol
Record protocol
The record protocol is the interface to the upper layer (transaction or session
layer) and to the lower layer (transport layer). It receives messages from the
upper layer to be transmitted, optionally compresses the data, applies a
message authentication code (MAC), encrypts the message, and then transmits
the message. Conversely, received data is decrypted, verified, decompressed,
and delivered to a higher layer of the client. The remaining four protocols
cooperate very closely with the record protocol in achieving these steps.
Handshake protocol
This protocol consists of three subprotocols that allow peers to agree on security
parameters for the record layer. The handshake protocol is responsible for the
negotiation process between the client and server and is employed when
initiating WTLS. These parameters are negotiated during the handshake:
Session identifier Identifies an active and resumeable secure
session.
Protocol version WTLS protocol version number.
Peer certificate Certificate of the peer.
Compression method The algorithm used to compress data prior to
encryption.
Chapter 18. Wireless Application Protocol 699