Zilog EZ80F91AZA - Manual (Page 31)

UM020107-1211 SSL Configuration
ZTP Network Security SSL Plug-In
User Manual
25
Each of the four supported digest algorithms has an entry that follows the NullHash_New
function pointer.
Each entry in the array is a function pointer that is used to initialize a data structure that the
SSL handshake protocols use to perform digest operations.
NullHash does not perform
any useful function, but it must be included in the HashGen array for proper operation of
the SSL protocol.
The ordering of entries in the HashGen array is not arbitrary, and is determined by the
ordinal values of the following macros (see the ez80_hash.h header file); the values of
these macros must not be altered.
#define SSL_HASH_NULL 0
#define SSL_HASH_MD5 1
#define SSL_HASH_HMAC_MD5 2
#define SSL_HASH_SHA1 3
#define SSL_HASH_HMAC_SHA1 4
Table 5 shows which digest algorithms are required for each of the SSL handshake proto-
cols. If the application uses combinations of protocols, select the last row in the table that
matches one of the SSL handshake protocols used. For example, if your project requires
the SSLv2 and TLSv1 handshake protocols, then the digest algorithms corresponding to
the TLSv1 handshake protocol must appear in the
HashGen array.
If a digest algorithm is not required, replace the corresponding entry in the HashGen array
with NullHash_New . For example, in an application required to support SSLv2 and
SSLv3, it is not necessary to include the HMAC_MD5 or HMAC_SHA1 digest algorithms;
therefore the project can be made slightly smaller by using the following HashGen array.
HASH_NEW HashGen[ SSL_MAX_HASH ] =
{
NullHash_New,
MD5_New,
Table 5. Mandatory Digest Algorithm by SSL Protocol Version
SSL Handshake

Protocol version Mandatory Digest Algorithms
SSLv2 MD5
SSLv3 MD5, SHA1
TLSv1 MD5, SHA1, HMAC_MD5, HMAC_SHA1
Note: