Implement tropic provisioning

[onvej-sl]

No description provided.

[github-actions]

en main(all)

model	device_test	click_test	persistence_test
T2T1	test(all) main(all)	test(all) main(all)	test(all) main(all)
T3B1	test(all) main(all)	test(all) main(all)	test(all) main(all)
T3T1	test(all) main(all)	test(all) main(all)	test(all) main(all)
T3W1	test(all) main(all)	test(all) main(all)	test(all) main(all)

Latest CI run: 17072904578

[andrewkozlik]

Partial review. Still need to look at prodtest_tropic.c.

[M-pasta]

prodtest_tropic.c checked

[andrewkozlik]

Partial review.

[andrewkozlik]

This code is duplicated across cert_write(), read_cert() and twice in is_paired(). We can define a function like this:

static bool tropic_handshake(int key_slot) {
  tropic_handshake_state = TROPIC_HANDSHAKE_STATE_0;

  lt_handle_t* tropic_handle = tropic_get_handle();

  curve25519_key tropic_public = {0};
  if (secret_key_tropic_public(tropic_public) != sectrue) {
    cli_error(cli, CLI_ERROR, "`secret_key_tropic_public()` failed.");
    goto cleanup;
  }

  curve25519_key private = {0};
  if (key_slot == PRIVILEGED_PAIRING_KEY_SLOT) {
    if (secret_key_tropic_pairing_privileged(private) != sectrue) {
      cli_error(cli, CLI_ERROR,
                "`secret_key_tropic_pairing_privileged()` failed.");
      goto cleanup;
    }
  } else if (key_slot == UNPRIVILEGED_PAIRING_KEY_SLOT) {
    if (secret_key_tropic_pairing_unprivileged(private) != sectrue) {
      cli_error(cli, CLI_ERROR,
                "`secret_key_tropic_pairing_unprivileged()` failed.");
      goto cleanup;
    }
  } else {
    cli_error(cli, CLI_ERROR,
              "Unknown key_slot.");
    goto cleanup;
  }

  curve25519_key public = {0};
  curve25519_scalarmult_basepoint(public, private);

  lt_ret_t ret =
      lt_session_start(tropic_handle, tropic_public, key_slot,
                       private, public);
  if (ret != LT_OK) {
    cli_error(cli, CLI_ERROR,
              "`lt_session_start()` for privileged key failed with error %d",
              ret);
    goto cleanup;
  }

cleanup:
  memzero(private, sizeof(private));
  return ret == LT_OK;  // TODO set ret correctly above
}

• Maybe we can reuse/replace tropic_init() from embed/sec/tropic/tropic.c? I didn't look closely enough. The error handling would probably complicate things.
• Probably makes sense to add FACTORY_PAIRING_KEY_SLOT to the if-else, so that it can be used in prodtest_tropic_pair(), again I didn't look close enough.

[andrewkozlik]

Also, I don't know how long the handshake takes, but we could optimize this, so that if the handshake is already active we don't repeat it. For example replace TROPIC_HANDSHAKE_STATE_1 with different states for each key:
TROPIC_HANDSHAKE_STATE_FACTORY
TROPIC_HANDSHAKE_STATE_PRIVILEGED
TROPIC_HANDSHAKE_STATE_UNPRIVILEGED
TROPIC_HANDSHAKE_STATE_HSM

[onvej-sl]

I agree with you, and I wanted to refactor it exactly as you suggested, but I considered it a low priority.

[onvej-sl]

I squashed all the fix-up commits, reordered the commits, and changed the commit messages. The diff between the old branch and the new branch is empty.

[onvej-sl]

I squashed 15934d0 and rebased on top of main, that most notably includes #5542 and #5539.

[onvej-sl]

@andrewkozlik Could you please review 01675e0?

[andrewkozlik]

utACK