Add comment to mbedtls_mpi_core_sub() to indicate it is costant time
Signed-off-by: Waleed Elmelegy <waleed.elmelegy@arm.com>
diff --git a/library/bignum_core.h b/library/bignum_core.h
index 92c8d47..bebd810 100644
--- a/library/bignum_core.h
+++ b/library/bignum_core.h
@@ -376,6 +376,9 @@
* \p X may be aliased to \p A or \p B, or even both, but may not overlap
* either otherwise.
*
+ * This function operates in constant time with respect to the values
+ * of \p X and \p A and \p B.
+ *
* \param[out] X The result of the subtraction.
* \param[in] A Little-endian presentation of left operand.
* \param[in] B Little-endian presentation of right operand.