From 5f099300176c462e034616b62a877052e99f8dd3 Mon Sep 17 00:00:00 2001 From: Tom Cosgrove Date: Fri, 9 Dec 2022 10:58:15 +0000 Subject: [PATCH] Clarify use of temporary in mbedtls_mpi_mod_raw_inv_prime() Signed-off-by: Tom Cosgrove --- library/bignum_mod_raw.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/library/bignum_mod_raw.c b/library/bignum_mod_raw.c index 03924d247..266d915f2 100644 --- a/library/bignum_mod_raw.c +++ b/library/bignum_mod_raw.c @@ -144,9 +144,12 @@ void mbedtls_mpi_mod_raw_inv_prime( mbedtls_mpi_uint *X, * |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 );