Clarify use of temporary in mbedtls_mpi_mod_raw_inv_prime()
Signed-off-by: Tom Cosgrove <tom.cosgrove@arm.com>
diff --git a/library/bignum_mod_raw.c b/library/bignum_mod_raw.c
index 03924d2..266d915 100644
--- a/library/bignum_mod_raw.c
+++ b/library/bignum_mod_raw.c
@@ -144,9 +144,12 @@
* |G| = N - 1, so we want
* g^(|G|-1) = g^(N - 2)
*/
+
+ /* Use the first AN_limbs of T to hold N - 2 */
mbedtls_mpi_uint *Nminus2 = T;
(void) mbedtls_mpi_core_sub_int( Nminus2, N, 2, AN_limbs );
+ /* Rest of T is given to exp_mod for its working space */
mbedtls_mpi_core_exp_mod( X,
A, N, AN_limbs, Nminus2, AN_limbs,
RR, T + AN_limbs );