Update documentation about optional f_rng parameter
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/include/mbedtls/ecp.h b/include/mbedtls/ecp.h
index 691415e..5f02e86 100644
--- a/include/mbedtls/ecp.h
+++ b/include/mbedtls/ecp.h
@@ -518,10 +518,13 @@
* operations for any valid m. It avoids any if-branch or
* array index depending on the value of m.
*
- * \note If f_rng is not NULL, it is used to randomize intermediate
- * results in order to prevent potential timing attacks
- * targeting these results. It is recommended to always
- * provide a non-NULL f_rng (the overhead is negligible).
+ * \note If \p f_rng is not NULL, it is used to randomize
+ * intermediate results to prevent potential timing attacks
+ * targeting these results. We recommend always providing
+ * a non-NULL \p f_rng. The overhead is negligible.
+ * Note: unless #MBEDTLS_ECP_NO_INTERNAL_RNG is defined, when
+ * \p f_rng is NULL, an internal RNG (seeded from the value
+ * of \p m) will be used instead.
*
* \param grp ECP group
* \param R Destination point