Use new CT interface in mbedtls_mpi_core_lt_ct
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/library/bignum_core.c b/library/bignum_core.c
index a23862b..7a77f07 100644
--- a/library/bignum_core.c
+++ b/library/bignum_core.c
@@ -166,15 +166,11 @@
return mbedtls_ct_bool_or(msll_mask, min_le_lsl);
}
-unsigned mbedtls_mpi_core_lt_ct(const mbedtls_mpi_uint *A,
- const mbedtls_mpi_uint *B,
- size_t limbs)
+mbedtls_ct_condition_t mbedtls_mpi_core_lt_ct(const mbedtls_mpi_uint *A,
+ const mbedtls_mpi_uint *B,
+ size_t limbs)
{
- unsigned ret, cond, done;
-
- /* The value of any of these variables is either 0 or 1 for the rest of
- * their scope. */
- ret = cond = done = 0;
+ mbedtls_ct_condition_t ret = MBEDTLS_CT_FALSE, cond = MBEDTLS_CT_FALSE, done = MBEDTLS_CT_FALSE;
for (size_t i = limbs; i > 0; i--) {
/*
@@ -184,8 +180,8 @@
* Again even if we can make a decision, we just mark the result and
* the fact that we are done and continue looping.
*/
- cond = mbedtls_ct_mpi_uint_lt(B[i - 1], A[i - 1]);
- done |= cond;
+ cond = mbedtls_ct_bool_lt(B[i - 1], A[i - 1]);
+ done = mbedtls_ct_bool_or(done, cond);
/*
* If A[i - 1] < B[i - 1] then A < B is true.
@@ -193,9 +189,9 @@
* Again even if we can make a decision, we just mark the result and
* the fact that we are done and continue looping.
*/
- cond = mbedtls_ct_mpi_uint_lt(A[i - 1], B[i - 1]);
- ret |= cond & (1 - done);
- done |= cond;
+ cond = mbedtls_ct_bool_lt(A[i - 1], B[i - 1]);
+ ret = mbedtls_ct_bool_or(ret, mbedtls_ct_bool_and(cond, mbedtls_ct_bool_not(done)));
+ done = mbedtls_ct_bool_or(done, cond);
}
/*
diff --git a/library/bignum_core.h b/library/bignum_core.h
index e2d18e9..64d51b9 100644
--- a/library/bignum_core.h
+++ b/library/bignum_core.h
@@ -161,13 +161,13 @@
* \param limbs The number of limbs in \p A and \p B.
* This must not be 0.
*
- * \return The result of the comparison:
- * \c 1 if \p A is less than \p B.
- * \c 0 if \p A is greater than or equal to \p B.
+ * \return MBEDTLS_CT_TRUE if \p A is less than \p B.
+ * MBEDTLS_CT_FALSE if \p A is greater than or equal to \p B.
*/
-unsigned mbedtls_mpi_core_lt_ct(const mbedtls_mpi_uint *A,
- const mbedtls_mpi_uint *B,
- size_t limbs);
+mbedtls_ct_condition_t mbedtls_mpi_core_lt_ct(const mbedtls_mpi_uint *A,
+ const mbedtls_mpi_uint *B,
+ size_t limbs);
+
/**
* \brief Perform a safe conditional copy of an MPI which doesn't reveal
* whether assignment was done or not.