+ /**
+ * \brief Multiply the generator by an integer.
+ *
+ * The multiplier MUST be non-zero and less than the curve
+ * subgroup order. Results are indeterminate if this property
+ * does not hold.
+ *
+ * \param R output buffer for the point.
+ * \param x multiplier (unsigned big-endian).
+ * \param xlen multiplier length (in bytes).
+ * \param curve curve identifier.
+ * \return encoded result point length (in bytes).
+ */
+ size_t (*mulgen)(unsigned char *R,
+ const unsigned char *x, size_t xlen, int curve);
+