Test range and format of dhm_make_params output
Improve the validation of the output from mbedtls_dhm_make_params:
* Test that the output in the byte buffer matches the value in the
context structure.
* Test that the calculated values are in the desired range.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/suites/test_suite_dhm.function b/tests/suites/test_suite_dhm.function
index 1726b9e..b9dcde5 100644
--- a/tests/suites/test_suite_dhm.function
+++ b/tests/suites/test_suite_dhm.function
@@ -1,5 +1,61 @@
/* BEGIN_HEADER */
#include "mbedtls/dhm.h"
+
+static int check_dhm_param_output( const mbedtls_mpi *expected,
+ const unsigned char *buffer,
+ size_t size,
+ size_t *offset )
+{
+ size_t n;
+ mbedtls_mpi actual;
+ int ok = 0;
+ mbedtls_mpi_init( &actual );
+
+ ++mbedtls_test_info.step;
+
+ TEST_ASSERT( size >= *offset + 2 );
+ n = ( buffer[*offset] << 8 ) | buffer[*offset + 1];
+ *offset += 2;
+ TEST_EQUAL( n, mbedtls_mpi_size( expected ) );
+ TEST_ASSERT( size >= *offset + n );
+ TEST_EQUAL( 0, mbedtls_mpi_read_binary( &actual, buffer + *offset, n ) );
+ TEST_EQUAL( 0, mbedtls_mpi_cmp_mpi( expected, &actual ) );
+ *offset += n;
+
+ ok = 1;
+exit:
+ mbedtls_mpi_free( &actual );
+ return( ok );
+}
+
+static int check_dhm_params( const mbedtls_dhm_context *ctx,
+ size_t x_size,
+ const unsigned char *ske, size_t ske_len )
+{
+ size_t offset = 0;
+
+ /* Check that ctx->X and ctx->GX are within range. */
+ TEST_ASSERT( mbedtls_mpi_cmp_int( &ctx->X, 1 ) > 0 );
+ TEST_ASSERT( mbedtls_mpi_cmp_mpi( &ctx->X, &ctx->P ) < 0 );
+ TEST_ASSERT( mbedtls_mpi_size( &ctx->X ) <= x_size );
+ TEST_ASSERT( mbedtls_mpi_cmp_int( &ctx->GX, 1 ) > 0 );
+ TEST_ASSERT( mbedtls_mpi_cmp_mpi( &ctx->GX, &ctx->P ) < 0 );
+
+ /* Check ske: it must contain P, G and G^X, each prefixed with a
+ * 2-byte size. */
+ if( !check_dhm_param_output( &ctx->P, ske, ske_len, &offset ) )
+ goto exit;
+ if( !check_dhm_param_output( &ctx->G, ske, ske_len, &offset ) )
+ goto exit;
+ if( !check_dhm_param_output( &ctx->GX, ske, ske_len, &offset ) )
+ goto exit;
+ TEST_EQUAL( offset, ske_len );
+
+ return( 1 );
+exit:
+ return( 0 );
+}
+
/* END_HEADER */
/* BEGIN_DEPENDENCIES
@@ -151,11 +207,14 @@
/*
* First key exchange
*/
+ mbedtls_test_set_step( 10 );
TEST_ASSERT( mbedtls_dhm_make_params( &ctx_srv, x_size, ske, &ske_len,
&mbedtls_test_rnd_pseudo_rand,
&rnd_info ) == result );
if ( result != 0 )
goto exit;
+ if( !check_dhm_params( &ctx_srv, x_size, ske, ske_len ) )
+ goto exit;
ske[ske_len++] = 0;
ske[ske_len++] = 0;
@@ -179,6 +238,7 @@
/* Re-do calc_secret on server a few times to test update of blinding values */
for( i = 0; i < 3; i++ )
{
+ mbedtls_test_set_step( 20 + i );
sec_srv_len = 1000;
TEST_ASSERT( mbedtls_dhm_calc_secret( &ctx_srv, sec_srv,
sizeof( sec_srv ), &sec_srv_len,
@@ -195,9 +255,12 @@
*/
p = ske;
+ mbedtls_test_set_step( 30 );
TEST_ASSERT( mbedtls_dhm_make_params( &ctx_srv, x_size, ske, &ske_len,
&mbedtls_test_rnd_pseudo_rand,
&rnd_info ) == 0 );
+ if( !check_dhm_params( &ctx_srv, x_size, ske, ske_len ) )
+ goto exit;
ske[ske_len++] = 0;
ske[ske_len++] = 0;
TEST_ASSERT( mbedtls_dhm_read_params( &ctx_cli, &p, ske + ske_len ) == 0 );