Zilog EZ80F91AZA - Manual (Page 30)

UM020107-1211 SSL Configuration
ZTP Network Security SSL Plug-In
User Manual
24
Client Mode or Server Mode Support
When each of the SSL handshake protocols is initialized (see the SSL Handshake Protocol
Initialization section on page 22), the first parameter on the initialization call specifies
whether the protocol supports the client and/or server mode of operation.
1. SSL sessions are always initialized by clients. Servers will only wait passively for
connection attempts from remote clients.
2. The SSL handshake protocols implemented in the ZTP Network Security SSL Plug-In
are capable of operating simultaneously. For example, it is possible that an SSLv3 cli-
ent session is being established at the same time as a TLSv1 server session and a
TLSv1 client session. However, when multiple sessions are established at the same
time, it takes longer for all sessions to be established than if they had been established
serially.
Digest Algorithm Selection
The SSL handshake protocols use digest algorithms for many purposes, including generat-
ing and verifying message authentication codes, generating session keys, and verifying
digital signatures. The ZTP Network Security SSL Plug-In recognizes the following four
digest (or hash) algorithms:
•
MD5
•
SHA1
•
HMAC_MD5
•
HMAC_SHA1

Depending on the SSL handshake protocols used and the configuration of cipher suites,
some of these digest algorithms can be removed from the project to reduce code size. This
removal can be performed by modifying
HashGen array in the hash_conf.c file.
The default setting of the HashGen array is shown in the following code fragment.
HASH_NEW HashGen[ SSL_MAX_HASH ] =
{
NullHash_New,
MD5_New,
HMAC_MD5_New,
SHA1_New,
HMAC_SHA1_New
};
Notes: