Note that (as usual) for mbedtls_mpi_mod_inv() residues must be associated with the modulus
Signed-off-by: Tom Cosgrove <tom.cosgrove@arm.com>
diff --git a/library/bignum_mod.h b/library/bignum_mod.h
index b2c36a9..a708be6 100644
--- a/library/bignum_mod.h
+++ b/library/bignum_mod.h
@@ -196,6 +196,9 @@
/**
* \brief Perform modular inversion of an MPI with respect to a modulus \p N.
*
+ * \p A and \p X must be associated with the modulus \p N and will therefore
+ * have the same number of limbs as \p N.
+ *
* \p X may be aliased to \p A.
*
* \warning Currently only supports prime moduli, but does not check for them.