replace_reply_key
krb5_error_code (*replace_reply_key)(krb5_context context,
replace_reply_key
retval = rs.preauth_cb->replace_reply_key(context, rs.rock, armor_key,
retval = cb->replace_reply_key(context, rock, &reply_key, FALSE);
ret = cb->replace_reply_key(context, rock, reply_key, TRUE);