DH_set_length
if (!DH_set_length(dh, MINIMUM(need * 2, pbits - 1)))
|| !DH_set_length(dh, priv_len)))
OSSL_DEPRECATEDIN_3_0 int DH_set_length(DH *dh, long length);
DH_set_length(dh, (long)gctx->priv_len);