diff options
Diffstat (limited to 'src/demo.c')
| -rw-r--r-- | src/demo.c | 190 |
1 files changed, 163 insertions, 27 deletions
@@ -28,6 +28,8 @@ #include "rand_stm32.h"
#include "packet_interface.h"
#include "noise.h"
+#include "hid_keycodes.h"
+#include "words.h"
#include <libopencm3/stm32/rcc.h>
#include <libopencm3/stm32/gpio.h>
@@ -40,13 +42,21 @@ #include <libopencmsis/core_cm3.h>
#include <stdint.h>
-#include <string.h>
#include <stdlib.h>
+#include <string.h>
#ifndef USE_STM32F4_USBH_DRIVER_FS
#error The full-speed USB driver must be enabled with USE_STM32F4_USBH_DRIVER_FS in usbh_config.h!
#endif
+#ifndef MAX_FAILED_HANDSHAKES
+#define MAX_FAILED_HANDSHAKES 3
+#endif
+
+
+static struct NoiseState noise_state;
+static uint8_t remote_key_reference[CURVE25519_KEY_LEN];
+
void _fini(void);
@@ -113,17 +123,99 @@ static void gpio_setup(void) gpio_mode_setup(GPIOE, GPIO_MODE_INPUT, GPIO_PUPD_PULLUP, GPIO3 | GPIO4);
}
-enum packet_types {
- _RESERVED = 0,
- HID_KEYBOARD_REPORT = 1,
- HID_MOUSE_REPORT = 2
-};
+struct hid_report {
+ uint8_t modifiers;
+ uint8_t _reserved;
+ uint8_t keycodes[6];
+} __attribute__((__packed__));
+
+static char pairing_buf[512];
+static size_t pairing_buf_pos = 0;
+
+int pairing_check(struct NoiseState *st, const char *buf);
+void pairing_input(uint8_t keycode);
+void pairing_parse_report(struct hid_report *buf, uint8_t len);
+
+int pairing_check(struct NoiseState *st, const char *buf) {
+ const char *p = buf;
+ int idx = 0;
+ do {
+ const char *found = strchr(p, ' ');
+ size_t plen = found ? (size_t)(found - p) : strlen(p); /* p >= found */
+ int num = -1;
+ for (int i=0; i<256; i++) {
+ if (!strncmp(p, adjectives[i], plen) || !strncmp(p, nouns[i], plen)) {
+ num = i;
+ break;
+ }
+ }
+ if (num == -1) {
+ LOG_PRINTF("Pairing word not found in dictionary\n");
+ return -1;
+ }
+ if (st->handshake_hash[idx] != num) {
+ LOG_PRINTF("Pairing data does not match hash\n");
+ return -1;
+ }
+ idx++;
+ p = strchr(p, ' ');
+ } while (p != NULL && idx < BLAKE2S_HASH_SIZE);
+
+ if (idx < 8) {
+ LOG_PRINTF("Pairing sequence too short, only %d bytes of hash checked\n", idx);
+ return -1;
+ }
-struct hid_report_packet {
- uint8_t type;
- uint8_t len;
- uint8_t report[8];
-};
+ return 0;
+}
+
+void pairing_input(uint8_t keycode) {
+ switch (keycode) {
+ case KEY_ENTER:
+ pairing_buf[pairing_buf_pos++] = '\0';
+ if (!pairing_check(&noise_state, pairing_buf)) {
+ persist_remote_key(&noise_state);
+ /* FIXME write key to backup memory */
+ }
+ break;
+
+ case KEY_BACKSPACE:
+ if (pairing_buf_pos > 0)
+ pairing_buf_pos--;
+ break;
+
+ default:
+ for (size_t i=0; i<sizeof(keycode_mapping)/sizeof(keycode_mapping[0]); i++) {
+ if (keycode_mapping[i].kc == keycode) {
+ if (pairing_buf_pos < sizeof(pairing_buf)-1) /* allow for terminating null byte */
+ pairing_buf[pairing_buf_pos++] = keycode_mapping[i].ch;
+ break;
+ }
+ }
+ break;
+ }
+}
+
+void pairing_parse_report(struct hid_report *buf, uint8_t len) {
+ static uint8_t old_keycodes[6] = {0};
+
+ for (int i=0; i<len-2; i++) {
+ if (!buf->keycodes[i])
+ break; /* keycodes are always populated from low to high */
+
+ int found = 0;
+ for (int j=0; j<6; j++) {
+ if (old_keycodes[j] == buf->keycodes[i]) {
+ found = 1;
+ break;
+ }
+ }
+ if (!found) /* key pressed */
+ pairing_input(buf->keycodes[i]);
+ }
+
+ memcpy(old_keycodes, buf->keycodes, 6);
+}
static void hid_in_message_handler(uint8_t device_id, const uint8_t *data, uint32_t length)
{
@@ -136,21 +228,34 @@ static void hid_in_message_handler(uint8_t device_id, const uint8_t *data, uint3 return;
}
- int type = hid_get_type(device_id);
- if (type != HID_TYPE_KEYBOARD && type != HID_TYPE_MOUSE) {
- LOG_PRINTF("Unsupported HID report type %x\n", type);
- return;
- }
-
LOG_PRINTF("Sending event %02X %02X %02X %02X\n", data[0], data[1], data[2], data[3]);
struct hid_report_packet pkt = {
- .type = type == HID_TYPE_KEYBOARD ? HID_KEYBOARD_REPORT : HID_MOUSE_REPORT,
.len = length,
.report = {0}
};
memcpy(pkt.report, data, length);
- if (send_encrypted_message((uint8_t *)&pkt, sizeof(pkt))) {
+ int type = hid_get_type(device_id);
+ if (type == HID_TYPE_KEYBOARD) {
+ if (noise_state.handshake_state == HANDSHAKE_DONE_UNKNOWN_HOST) {
+ pkt.type = PAIRING;
+ pairing_parse_report((struct hid_report *)data, length);
+ } else {
+ pkt.type = HID_KEYBOARD_REPORT;
+ }
+ } else if (type == HID_TYPE_MOUSE) {
+ if (noise_state.handshake_state == HANDSHAKE_DONE_UNKNOWN_HOST) {
+ LOG_PRINTF("Not sending HID mouse report during pairing\n");
+ return;
+ } else {
+ pkt.type = HID_MOUSE_REPORT;
+ }
+ } else {
+ LOG_PRINTF("Unsupported HID report type %x\n", type);
+ return;
+ }
+
+ if (send_encrypted_message(&noise_state, (uint8_t *)&pkt, sizeof(pkt))) {
LOG_PRINTF("Error sending HID report packet\n");
return;
}
@@ -213,21 +318,52 @@ int main(void) LOG_PRINTF("Initializing RNG...\n");
rand_init();
+ noise_state_init(&noise_state, remote_key_reference);
+ /* 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())
+ if (generate_identity_key(&noise_state))
LOG_PRINTF("Error generating identiy key\n");
- LOG_PRINTF("Starting noise protocol handshake...\n");
- NoiseHandshakeState *handshake = start_protocol_handshake();
- if (!handshake)
- LOG_PRINTF("Error starting protocol handshake.\n");
-
while (23) {
usbh_poll(tim6_get_time_us());
- if (handshake)
- handshake = try_continue_noise_handshake(handshake);
+ if (host_packet_length > 0) {
+ struct control_packet *pkt = (struct control_packet *)host_packet_buf;
+ size_t payload_length = host_packet_length - 1;
+
+ if (pkt->type == HOST_INITIATE_HANDSHAKE) {
+ /* It is important that we acknowledge this command right away. Starting the handshake involves key
+ * generation which takes a few milliseconds. If we'd acknowledge this later, we might run into an
+ * overrun here since we would be blocking the buffer during key generation. */
+ host_packet_length = 0; /* Acknowledge to USART ISR the buffer has been handled */
+
+ if (payload_length > 0) {
+ LOG_PRINTF("Extraneous data in INITIATE_HANDSHAKE message\n");
+ } else if (noise_state.failed_handshakes < MAX_FAILED_HANDSHAKES) {
+ LOG_PRINTF("Starting noise protocol handshake...\n");
+ if (reset_protocol_handshake(&noise_state))
+ LOG_PRINTF("Error starting protocol handshake.\n");
+ pairing_buf_pos = 0; /* Reset channel binding keyboard input buffer */
+ } else {
+ LOG_PRINTF("Too many failed handshake attempts, not starting another one\n");
+ }
+ } else if (pkt->type == HOST_HANDSHAKE) {
+ LOG_PRINTF("Handling handshake packet of length %d\n", payload_length);
+ int consumed = 0;
+ try_continue_noise_handshake(&noise_state, pkt->payload, payload_length, &consumed);
+ if (consumed)
+ host_packet_length = 0; /* Acknowledge to USART ISR the buffer has been handled */
+ else /* Otherwise this gets called again in the next iteration of the main loop. Usually that should not happen. */
+ LOG_PRINTF("Handshake buffer unhandled. Waiting for next iteration.\n");
+
+ } else {
+ host_packet_length = 0; /* Acknowledge to USART ISR the buffer has been handled */
+ }
+ }
+
+ if (noise_state.handshake_state == HANDSHAKE_IN_PROGRESS)
+ try_continue_noise_handshake(&noise_state, NULL, 0, NULL); /* handle outgoing messages */
delay_ms_busy_loop(1); /* approx 1ms interval between usbh_poll() */
}
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