Properties used to specify the path to the local ID (certificates) file.
typedef struct _cs_sslid { CS_CHAR *identity_file; CS_CHAR *identity_password; } CS_SSLIDENTITY
provides a path to the file containing a digital certificate and the associated private key.
CS_GET only returns the indentity_file used, and only if it is set with CS_CONNECTION.
used to decrypt the private key.