commit 618be2ec41012fe390ad9a0eecc9e8d706fc9859
author Gilles Peskine <Gilles.Peskine@arm.com> Sat Apr 03 21:47:53 2021 +0200
committer Gilles Peskine <Gilles.Peskine@arm.com> Sun Apr 04 01:10:41 2021 +0200
tree 6b5019683c6a1ac03563ea9eff8088a17b3e9bca
parent 80ba850e277e2e87f820e64e54989738b7c276cb

Add unit tests for fix_negative

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

tests/suites/test_suite_ecp.function

diff --git a/tests/suites/test_suite_ecp.function b/tests/suites/test_suite_ecp.function
index 8d47eda..0ca2fdf 100644
--- a/tests/suites/test_suite_ecp.function
+++ b/tests/suites/test_suite_ecp.function
@@ -1,6 +1,15 @@
 /* BEGIN_HEADER */
 #include "mbedtls/ecp.h"
 
+#include "ecp_invasive.h"
+
+#if defined(MBEDTLS_TEST_HOOKS) &&                  \
+    ( defined(MBEDTLS_ECP_DP_SECP224R1_ENABLED) ||  \
+      defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED) ||  \
+      defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED) )
+#define HAVE_FIX_NEGATIVE
+#endif
+
 #define ECP_PF_UNKNOWN     -1
 
 #define ECP_PT_RESET( x )           \
@@ -1198,6 +1207,36 @@
 }
 /* END_CASE */
 
+/* BEGIN_CASE depends_on:HAVE_FIX_NEGATIVE */
+void fix_negative( data_t *N_bin, int c, int bits )
+{
+    mbedtls_mpi C, M, N;
+
+    mbedtls_mpi_init( &C );
+    mbedtls_mpi_init( &M );
+    mbedtls_mpi_init( &N );
+
+    /* C = - c * 2^bits */
+    TEST_EQUAL( 0, mbedtls_mpi_lset( &C, -c ) );
+    TEST_EQUAL( 0, mbedtls_mpi_shift_l( &C, bits ) );
+
+    TEST_EQUAL( 0, mbedtls_mpi_read_binary( &N, N_bin->x, N_bin->len ) );
+    TEST_EQUAL( 0, mbedtls_mpi_grow( &N, C.n ) );
+
+    /* M = - ( C - N ) */
+    TEST_EQUAL( 0, mbedtls_mpi_sub_mpi( &M, &N, &C ) );
+
+    mbedtls_ecp_fix_negative( &N, c, bits );
+
+    TEST_EQUAL( 0, mbedtls_mpi_cmp_mpi( &N, &M ) );
+
+exit:
+    mbedtls_mpi_free( &C );
+    mbedtls_mpi_free( &M );
+    mbedtls_mpi_free( &N );
+}
+/* END_CASE */
+
 /* BEGIN_CASE depends_on:MBEDTLS_SELF_TEST */
 void ecp_selftest(  )
 {