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sm: reduce mbedtls heap to less than 800 bytes for 32-bit CPUs. Use mbedtls_mpi_lset instead of mbedtls_mpi_read_string

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This commit is contained in:
Matthias Ringwald 2016-06-29 11:03:11 +02:00
parent 1bf28f67a5
commit ae4aa2b6a5
1 changed files with 17 additions and 10 deletions
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27
src/ble/sm.c
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@ -231,8 +231,11 @@ static uint8_t ec_qx[32];
static uint8_t ec_qy[32];
static uint8_t ec_d[32];
#ifndef HAVE_MALLOC
// 4304 bytes with 73 allocations
#define MBEDTLS_ALLOC_BUFFER_SIZE (1300+23*sizeof(void *))
// COMP Method with Window 2
// 1300 bytes with 23 allocations
// #define MBEDTLS_ALLOC_BUFFER_SIZE (1300+23*sizeof(void *))
// NAIVE Method with safe cond assignments (without safe cond, order changes and allocations fail)
#define MBEDTLS_ALLOC_BUFFER_SIZE (700+18*sizeof(void *))
static uint8_t mbedtls_memory_buffer[MBEDTLS_ALLOC_BUFFER_SIZE];
#endif
#endif
@ -1494,12 +1497,12 @@ static void sm_sc_calculate_dhkey(sm_key256_t dhkey){
mbedtls_mpi_read_binary(&d, ec_d, 32);
mbedtls_mpi_read_binary(&Q.X, setup->sm_peer_qx, 32);
mbedtls_mpi_read_binary(&Q.Y, setup->sm_peer_qy, 32);
mbedtls_mpi_read_string(&Q.Z, 16, "1" );
mbedtls_mpi_lset(&Q.Z, 1);
mbedtls_ecp_mul(&mbedtls_ec_group, &DH, &d, &Q, NULL, NULL);
mbedtls_mpi_write_binary(&DH.X, dhkey, 32);
mbedtls_ecp_point_free(&DH);
mbedtls_mpi_free(&d);
mbedtls_ecp_point_free(&Q);
mbedtls_ecp_point_free(&DH);
#endif
log_info("dhkey");
log_info_hexdump(dhkey, 32);
@ -2687,6 +2690,7 @@ static void sm_handle_random_result(uint8_t * data){
setup->sm_passkey_bit = num_bytes;
if (num_bytes >= 64){
// generate EC key
setup->sm_passkey_bit = 0;
mbedtls_mpi d;
@ -2704,11 +2708,15 @@ static void sm_handle_random_result(uint8_t * data){
sm_log_ec_keypair();
#if 0
printf("test dhkey check\n");
int i;
sm_key256_t dhkey;
memcpy(setup->sm_peer_qx, ec_qx, 32);
memcpy(setup->sm_peer_qy, ec_qy, 32);
sm_sc_calculate_dhkey(dhkey);
for (i=0;i<10;i++){
// printf("test dhkey check\n");
memcpy(setup->sm_peer_qx, ec_qx, 32);
memcpy(setup->sm_peer_qy, ec_qy, 32);
sm_sc_calculate_dhkey(dhkey);
// printf("test dhkey check end\n");
}
#endif
}
@ -3248,7 +3256,7 @@ static void sm_pdu_handler(uint8_t packet_type, hci_con_handle_t con_handle, uin
mbedtls_ecp_point_init( &Q );
mbedtls_mpi_read_binary(&Q.X, setup->sm_peer_qx, 32);
mbedtls_mpi_read_binary(&Q.Y, setup->sm_peer_qy, 32);
mbedtls_mpi_read_string(&Q.Z, 16, "1" );
mbedtls_mpi_lset(&Q.Z, 1);
err = mbedtls_ecp_check_pubkey(&mbedtls_ec_group, &Q);
mbedtls_ecp_point_free( & Q);
if (err){
@ -3565,7 +3573,6 @@ void sm_init(void){
#endif
mbedtls_ecp_group_init(&mbedtls_ec_group);
mbedtls_ecp_group_load(&mbedtls_ec_group, MBEDTLS_ECP_DP_SECP256R1);
#if 0
// test
sm_test_use_fixed_ec_keypair();