MPI random: add unit tests with a previously nonzero value
Add unit tests for mbedtls_mpi_fill_random() and mbedtls_mpi_random()
when the resulting MPI object previously had a nonzero value. I wrote
those to catch a bug that I introduced during the development of
mbedtls_mpi_random() (but does not appear in a committed version).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/suites/test_suite_mpi.function b/tests/suites/test_suite_mpi.function
index f3c9107..e82fe99 100644
--- a/tests/suites/test_suite_mpi.function
+++ b/tests/suites/test_suite_mpi.function
@@ -1400,13 +1400,23 @@
/* END_CASE */
/* BEGIN_CASE */
-void mpi_fill_random( int wanted_bytes, int rng_bytes, int expected_ret )
+void mpi_fill_random( int wanted_bytes, int rng_bytes,
+ int before, int expected_ret )
{
mbedtls_mpi X;
int ret;
size_t bytes_left = rng_bytes;
mbedtls_mpi_init( &X );
+ if( before != 0 )
+ {
+ /* Set X to sign(before) * 2^(|before|-1) */
+ TEST_ASSERT( mbedtls_mpi_lset( &X, before > 0 ? 1 : -1 ) == 0 );
+ if( before < 0 )
+ before = - before;
+ TEST_ASSERT( mbedtls_mpi_shift_l( &X, before - 1 ) == 0 );
+ }
+
ret = mbedtls_mpi_fill_random( &X, wanted_bytes,
f_rng_bytes_left, &bytes_left );
TEST_ASSERT( ret == expected_ret );
@@ -1538,7 +1548,7 @@
/* END_CASE */
/* BEGIN_CASE */
-void mpi_random_grown( int min, data_t *bound_bytes, int nlimbs )
+void mpi_random_sizes( int min, data_t *bound_bytes, int nlimbs, int before )
{
mbedtls_mpi upper_bound;
mbedtls_mpi result;
@@ -1546,6 +1556,15 @@
mbedtls_mpi_init( &upper_bound );
mbedtls_mpi_init( &result );
+ if( before != 0 )
+ {
+ /* Set result to sign(before) * 2^(|before|-1) */
+ TEST_ASSERT( mbedtls_mpi_lset( &result, before > 0 ? 1 : -1 ) == 0 );
+ if( before < 0 )
+ before = - before;
+ TEST_ASSERT( mbedtls_mpi_shift_l( &result, before - 1 ) == 0 );
+ }
+
TEST_EQUAL( 0, mbedtls_mpi_grow( &result, nlimbs ) );
TEST_EQUAL( 0, mbedtls_mpi_read_binary( &upper_bound,
bound_bytes->x, bound_bytes->len ) );