Fix non-opaque use of mbedtls_ct_condition_t
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/library/bignum.c b/library/bignum.c
index 30a30dd..8ad7258 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -96,8 +96,8 @@
/* This is used to conditionally swap the pointers in const time */
void * const p[2] = { X->p, Y->p };
- mbedtls_ct_condition_t lt = mbedtls_mpi_core_lt_ct(
- p[X_is_negative & 1], p[(X_is_negative & 1) ^ 1], X->n);
+ size_t i = mbedtls_ct_size_if0(X_is_negative, 1);
+ mbedtls_ct_condition_t lt = mbedtls_mpi_core_lt_ct(p[i], p[i ^ 1], X->n);
result = mbedtls_ct_bool_or(result, mbedtls_ct_bool_and(mbedtls_ct_bool_not(cond), lt));