- return zc->iec->mul(data, len, zc->sk->x, zc->sk->xlen, zc->sk->curve);
+ r = zc->iec->mul(data, *len, zc->sk->x, zc->sk->xlen, zc->sk->curve);
+ xoff = zc->iec->xoff(zc->sk->curve, &xlen);
+ memmove(data, data + xoff, xlen);
+ *len = xlen;
+ return r;