update_thash
ret = update_thash(context, gstate, ch->group, &st->thash, st->support,
ret = update_thash(context, gstate, ch->group, &st->thash, &clpub, NULL);
ret = update_thash(context, gstate, group, &thash, support, der_msg);
ret = update_thash(context, gstate, group, &thash, &resp->pubkey, NULL);
check(update_thash(ctx, gstate, t->group, &hash, support, challenge));
check(update_thash(ctx, gstate, t->group, &hash, S, &empty));
krb5_error_code update_thash(krb5_context context, groupstate *gstate,