Add test case for ecdh_calc_secret

Add a test case for doing an ECDH calculation by calling
mbedtls_ecdh_get_params on both keys, then mbedtls_ecdh_calc_secret.

Author: gilles-peskine-arm

tests/suites/test_suite_ecdh.data

@@ -79,3 +79,11 @@ ecdh_restart:MBEDTLS_ECP_DP_SECP256R1:"C88F01F510D9AC3F70A292DAA2316DE544E9AAB8A
 ECDH exchange legacy context
 depends_on:MBEDTLS_ECP_DP_SECP192R1_ENABLED
 ecdh_exchange_legacy:MBEDTLS_ECP_DP_SECP192R1
+
+ECDH calc_secret: ours first, SECP256R1 (RFC 5903)
+depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
+ecdh_exchange_calc_secret:MBEDTLS_ECP_DP_SECP256R1:"c6ef9c5d78ae012a011164acb397ce2088685d8f06bf9be0b283ab46476bee53":"04dad0b65394221cf9b051e1feca5787d098dfe637fc90b9ef945d0c37725811805271a0461cdb8252d61f1c456fa3e59ab1f45b33accf5f58389e0577b8990bb3":0:"d6840f6b42f6edafd13116e0e12565202fef8e9ece7dce03812464d04b9442de"
+
+ECDH calc_secret: theirs first, SECP256R1 (RFC 5903)
+depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
+ecdh_exchange_calc_secret:MBEDTLS_ECP_DP_SECP256R1:"c6ef9c5d78ae012a011164acb397ce2088685d8f06bf9be0b283ab46476bee53":"04dad0b65394221cf9b051e1feca5787d098dfe637fc90b9ef945d0c37725811805271a0461cdb8252d61f1c456fa3e59ab1f45b33accf5f58389e0577b8990bb3":1:"d6840f6b42f6edafd13116e0e12565202fef8e9ece7dce03812464d04b9442de"

tests/suites/test_suite_ecdh.function

@@ -1,5 +1,41 @@
 /* BEGIN_HEADER */
 #include "mbedtls/ecdh.h"
+
+static int load_public_key( int grp_id, data_t *point,
+                            mbedtls_ecp_keypair *ecp )
+{
+    int ok = 0;
+    TEST_ASSERT( mbedtls_ecp_group_load( &ecp->grp, grp_id ) == 0 );
+    TEST_ASSERT( mbedtls_ecp_point_read_binary( &ecp->grp,
+                                                &ecp->Q,
+                                                point->x,
+                                                point->len ) == 0 );
+    TEST_ASSERT( mbedtls_ecp_check_pubkey( &ecp->grp,
+                                           &ecp->Q ) == 0 );
+    ok = 1;
+exit:
+    return( ok );
+}
+
+static int load_private_key( int grp_id, data_t *private_key,
+                             mbedtls_ecp_keypair *ecp,
+                             rnd_pseudo_info *rnd_info )
+{
+    int ok = 0;
+    TEST_ASSERT( mbedtls_ecp_group_load( &ecp->grp, grp_id ) == 0 );
+    TEST_ASSERT( mbedtls_mpi_read_binary( &ecp->d,
+                                          private_key->x,
+                                          private_key->len ) == 0 );
+    TEST_ASSERT( mbedtls_ecp_check_privkey( &ecp->grp, &ecp->d ) == 0 );
+    /* Calculate the public key from the private key. */
+    TEST_ASSERT( mbedtls_ecp_mul( &ecp->grp, &ecp->Q, &ecp->d,
+                                  &ecp->grp.G,
+                                  &rnd_pseudo_rand, rnd_info ) == 0 );
+    ok = 1;
+exit:
+    return( ok );
+}
+
 /* END_HEADER */
 
 /* BEGIN_DEPENDENCIES
@@ -464,3 +500,60 @@ exit:
     mbedtls_ecdh_free( &cli );
 }
 /* END_CASE */
+
+/* BEGIN_CASE */
+void ecdh_exchange_calc_secret( int grp_id,
+                                data_t *our_private_key,
+                                data_t *their_point,
+                                int ours_first,
+                                data_t *expected )
+{
+    rnd_pseudo_info rnd_info;
+    mbedtls_ecp_keypair our_key;
+    mbedtls_ecp_keypair their_key;
+    mbedtls_ecdh_context ecdh;
+    unsigned char shared_secret[MBEDTLS_ECP_MAX_BYTES];
+    size_t shared_secret_length = 0;
+
+    memset( &rnd_info, 0x00, sizeof( rnd_pseudo_info ) );
+    mbedtls_ecdh_init( &ecdh );
+    mbedtls_ecp_keypair_init( &our_key );
+    mbedtls_ecp_keypair_init( &their_key );
+
+    if( ! load_private_key( grp_id, our_private_key, &our_key, &rnd_info ) )
+        goto exit;
+    if( ! load_public_key( grp_id, their_point, &their_key ) )
+        goto exit;
+
+    /* Import the keys to the ECDH calculation. */
+    if( ours_first )
+    {
+        TEST_ASSERT( mbedtls_ecdh_get_params(
+                         &ecdh, &our_key, MBEDTLS_ECDH_OURS ) == 0 );
+        TEST_ASSERT( mbedtls_ecdh_get_params(
+                         &ecdh, &their_key, MBEDTLS_ECDH_THEIRS ) == 0 );
+    }
+    else
+    {
+        TEST_ASSERT( mbedtls_ecdh_get_params(
+                         &ecdh, &their_key, MBEDTLS_ECDH_THEIRS ) == 0 );
+        TEST_ASSERT( mbedtls_ecdh_get_params(
+                         &ecdh, &our_key, MBEDTLS_ECDH_OURS ) == 0 );
+    }
+
+    /* Perform the ECDH calculation. */
+    TEST_ASSERT( mbedtls_ecdh_calc_secret(
+                     &ecdh,
+                     &shared_secret_length,
+                     shared_secret, sizeof( shared_secret ),
+                     &rnd_pseudo_rand, &rnd_info ) == 0 );
+    TEST_ASSERT( shared_secret_length == expected->len );
+    TEST_ASSERT( memcmp( expected->x, shared_secret,
+                         shared_secret_length ) == 0 );
+
+exit:
+    mbedtls_ecdh_free( &ecdh );
+    mbedtls_ecp_keypair_free( &our_key );
+    mbedtls_ecp_keypair_free( &their_key );
+}
+/* END_CASE */