sam_make_challenge
krb5_error_code sam_make_challenge(krb5_context context,
ret = sam_make_challenge(context, &sc2b, client_key, sc2_out);
retval = sam_make_challenge(context, &sc2b, client_key, sc2);
retval = sam_make_challenge(context, &sc2b, &client_key, sc2p);
retval = sam_make_challenge(context, &sc2b, &client_key, sc2p);