Zilog EZ80F91AZA - Manual (Page 10)

UM020107-1211 Introduction
ZTP Network Security SSL Plug-In
User Manual
4
The handshake protocol module is responsible for establishing SSL sessions. This module
actually contains six sub-modules:
1. SSLv2 Client
2. SSLv2 Server
3. SSLv3 Client
4. SSLv3 Server
5. TLSv1 Client
6. TLSv1 Server

The module used to establish an SSL session depends on the configuration of the ZTP
Network Security SSL Plug-In. It is possible for multiple handshake modules to be active
at the same time.
SSL Session Cache Module. Adjacent to the handshake module is the SSL session
cache module, which is used to store information about the established SSL sessions. If
the same client and server attempt to establish another session in the future, the session
cache can be enabled to reduce the number of handshake messages that must be
exchanged, which will in turn reduce the session establishment time. This reduction is pri-
marily a result of not having to perform complex public key algorithms.
SSL Interface Module. Above the handshake module is the SSL interface module. This
layer exposes the SSL API to upper-layer applications. Other than the SSL-specific initial-
ization commands (
Initialize_SSL , SSL2_ClientInit , SSL2_ServerInit ,
SSL3_ClientInit , SSL3_ServerInit , TLS1_ClientInit , and
TLS1_ServerInit ), this interface exposes the same TCP interface as used by the TCP
Interface module. This exposure allows user applications that are written to use ZTP’s
TCP interface to be seamlessly ported to use SSL.
SSL Cryptographic Module. The final module in the ZTP Network Security SSL Plug-In
is the cryptographic module, which contains the digest algorithms, ciphers and public key
algorithms used by the SSL protocol to secure application data.
How to Use SSL
The Initialize_SSL API must be called to enable the SSL Interface layer used by
applications to securely transfer data. This API must be called only one time during sys-
tem initialization, regardless of how many SSL client and server tasks are created. Addi-
tionally, an initialization call must be made for each version of the SSL handshake
protocol that will be supported by the application. This initialization routine is accom-
plished by calling one or more of the following APIs:
•
SSL2_ClientInit
•
SSL2_ServerInit