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known device/sram data persistence working

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This commit is contained in:
jaseg 2018-11-14 22:47:04 +09:00
parent 66f9e82c5c
commit eb481f1cda
5 changed files with 53 additions and 14 deletions
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23
src/demo.c
View file

@ -38,6 +38,7 @@
#include <libopencm3/stm32/timer.h>
#include <libopencm3/stm32/otg_hs.h>
#include <libopencm3/stm32/otg_fs.h>
#include <libopencm3/stm32/pwr.h>
#include <libopencm3/stm32/dma.h>
#include <libopencm3/cm3/nvic.h>
#include <libopencmsis/core_cm3.h>
@ -56,7 +57,9 @@
static struct NoiseState noise_state;
static uint8_t remote_key_reference[CURVE25519_KEY_LEN];
static uint8_t remote_key_reference[BLAKE2S_HASH_SIZE] __attribute__((section(".backup_sram")));
static uint8_t local_key[CURVE25519_KEY_LEN] __attribute__((section(".backup_sram")));
static uint8_t identity_key_valid __attribute__((section(".backup_sram"))) = 0;
void _fini(void);
@ -81,6 +84,9 @@ static void clock_setup(void) {
rcc_periph_clock_enable(RCC_DMA2);
rcc_periph_clock_enable(RCC_DMA1);
rcc_periph_clock_enable(RCC_PWR);
rcc_periph_clock_enable(RCC_BKPSRAM);
rcc_periph_clock_enable(RCC_RNG);
}
@ -413,6 +419,8 @@ int main(void)
{
clock_setup();
gpio_setup();
pwr_disable_backup_domain_write_protect();
PWR_CSR |= PWR_CSR_BRE; /* Enable backup SRAM battery power regulator */
/* provides time_curr_us to usbh_poll function */
tim6_setup();
@ -447,12 +455,17 @@ int main(void)
LOG_PRINTF("Initializing RNG...\n");
rand_init();
noise_state_init(&noise_state, remote_key_reference);
noise_state_init(&noise_state, remote_key_reference, local_key);
/* FIXME load remote key from backup memory */
/* FIXME only run this on first boot and persist key in backup sram. Allow reset via jumper-triggered factory reset function. */
LOG_PRINTF("Generating identity key...\n");
if (generate_identity_key(&noise_state))
LOG_PRINTF("Error generating identiy key\n");
if (!identity_key_valid) {
LOG_PRINTF("Generating identity key...\n");
if (generate_identity_key(&noise_state)) {
LOG_PRINTF("Error generating identiy key\n");
} else {
identity_key_valid = 1;
}
}
int poll_ctr = 0;
while (23) {

24
src/noise.c
View file

@ -3,6 +3,9 @@
#include "noise.h"
#include "packet_interface.h"
#include "rand_stm32.h"
#include "crypto/noise-c/src/crypto/blake2/blake2s.h"
#define HANDLE_NOISE_ERROR(x, msg) do { \
@ -20,12 +23,13 @@ volatile uint8_t host_packet_buf[MAX_HOST_PACKET_SIZE];
volatile int host_packet_length = 0;
void noise_state_init(struct NoiseState *st, uint8_t *remote_key_reference) {
void noise_state_init(struct NoiseState *st, uint8_t *remote_key_reference, uint8_t *local_key) {
st->handshake_state = HANDSHAKE_UNINITIALIZED;
st->handshake = NULL;
st->tx_cipher = NULL;
st->rx_cipher = NULL;
st->remote_key_reference = remote_key_reference;
st->local_key = local_key;
st->failed_handshakes = 0;
}
@ -51,7 +55,7 @@ int start_protocol_handshake(struct NoiseState *st) {
HANDLE_NOISE_ERROR(noise_handshakestate_new_by_name(&handshake, "Noise_XX_25519_ChaChaPoly_BLAKE2s", NOISE_ROLE_RESPONDER), "instantiating handshake pattern");
NoiseDHState *dh = noise_handshakestate_get_local_keypair_dh(handshake);
HANDLE_NOISE_ERROR(noise_dhstate_set_keypair_private(dh, st->local_key, sizeof(st->local_key)), "loading local private keys");
HANDLE_NOISE_ERROR(noise_dhstate_set_keypair_private(dh, st->local_key, CURVE25519_KEY_LEN), "loading local private keys");
HANDLE_NOISE_ERROR(noise_handshakestate_start(handshake), "starting handshake");
@ -74,7 +78,7 @@ int generate_identity_key(struct NoiseState *st) {
uint8_t unused[CURVE25519_KEY_LEN]; /* the noise api is a bit bad here. */
memset(st->local_key, 0, sizeof(st->local_key));
HANDLE_NOISE_ERROR(noise_dhstate_get_keypair(dh, st->local_key, sizeof(st->local_key), unused, sizeof(unused)), "saving key pair");
HANDLE_NOISE_ERROR(noise_dhstate_get_keypair(dh, st->local_key, CURVE25519_KEY_LEN, unused, sizeof(unused)), "saving key pair");
return 0;
errout:
@ -146,7 +150,14 @@ int try_continue_noise_handshake(struct NoiseState *st, uint8_t *buf, size_t len
HANDLE_NOISE_ERROR(noise_dhstate_get_public_key(remote_dh, st->remote_key, sizeof(st->remote_key)), "getting remote pubkey");
if (!memcmp(st->remote_key, st->remote_key_reference, sizeof(st->remote_key))) { /* keys match */
/* TODO support list of known remote hosts here instead of just one */
uint8_t remote_fp[BLAKE2S_HASH_SIZE];
BLAKE2s_context_t bc;
BLAKE2s_reset(&bc);
BLAKE2s_update(&bc, st->remote_key, sizeof(st->remote_key));
BLAKE2s_finish(&bc, remote_fp);
if (!memcmp(remote_fp, st->remote_key_reference, sizeof(remote_fp))) { /* keys match */
uint8_t response = REPORT_PAIRING_SUCCESS;
if (send_encrypted_message(st, &response, sizeof(response)))
LOG_PRINTF("Error sending pairing response packet\n");
@ -177,7 +188,10 @@ errout:
}
void persist_remote_key(struct NoiseState *st) {
memcpy(st->remote_key_reference, st->remote_key, sizeof(st->remote_key));
BLAKE2s_context_t bc;
BLAKE2s_reset(&bc);
BLAKE2s_update(&bc, st->remote_key, sizeof(st->remote_key));
BLAKE2s_finish(&bc, st->remote_key_reference);
st->handshake_state = HANDSHAKE_DONE_KNOWN_HOST;
}

4
src/noise.h
View file

@ -30,7 +30,7 @@ struct NoiseState {
NoiseHandshakeState *handshake;
enum handshake_state handshake_state;
NoiseCipherState *tx_cipher, *rx_cipher;
uint8_t local_key[CURVE25519_KEY_LEN];
uint8_t *local_key;
uint8_t remote_key[CURVE25519_KEY_LEN];
uint8_t *remote_key_reference;
uint8_t handshake_hash[BLAKE2S_HASH_SIZE];
@ -39,7 +39,7 @@ struct NoiseState {
void uninit_handshake(struct NoiseState *st, enum handshake_state new_state);
void noise_state_init(struct NoiseState *st, uint8_t *remote_key_reference);
void noise_state_init(struct NoiseState *st, uint8_t *remote_key_reference, uint8_t *local_key);
void persist_remote_key(struct NoiseState *st);
int start_protocol_handshake(struct NoiseState *st);
int reset_protocol_handshake(struct NoiseState *st);