Mention that mpi_fill_random interprets PRNG output as big-endian
@@ -683,6 +683,10 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A, const mbedtls_mpi
*
* \return 0 if successful,
* MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed
+ *
+ * \note The bytes obtained from the PRNG are interpreted
+ * as a big-endian representation of an MPI; this can
+ * be relevant in applications like deterministic ECDSA.
*/
int mbedtls_mpi_fill_random( mbedtls_mpi *X, size_t size,
int (*f_rng)(void *, unsigned char *, size_t),
