notes

notes.md

@@ -61,7 +61,7 @@ https://www.1000rr.net/threads/k-line-ecu-logging.247922/
 
  - 2016 forum thread "Whipped up a simple circuit to interface with
    the K-Line interface found on that red adapter under the seat. "
- 
+
 https://www.carlsalter.com/mcpdf/Honda%20-%20cbr125rw-service-manual.pdf
  - wirig diagram, yay. !Caution: this is 2007 model!
  pin 1 Bl/W IGP "ignition power" (also seen on DLC)
@@ -169,3 +169,50 @@ O wifi provisioning over ble
 - add an IMU to get lean angles
 - stop hardcoding BLE address
 ```
+
+---
+
+We don't think impersonation is a big threat, because it requires
+having physical access and the ignition key in order to power on the
+device
+
+However, there is the problem that the wifi password is transmitted plaintext
+so an attacker could use this to get access to the wifi.
+
+In the current hardware confiudation, BLE pairing won't help, as it is
+susceptible to MITM without a display and an input device.  While it
+is conceivable that there is some input to the ECU we could could
+co-opt for saying "yes" or "no" to a displayed PIN, there is nowhere
+to display it.
+
+If we add an NFC transceiver we could use OOB pairing. the nfc chip
+could be stuck to the inside of the rear tail fairing just next to the
+ecu. The need for physical access makes it more secure but also a bit
+less convenient for pairing with a bluetooth in the shed when the bike
+is parked (e.g. to do ota updates)
+
+how about using the ed25519 key we have for ota/sessionm auth?
+
+1) the device generates a random 32 byte token, then encrypts it using the
+client's private ed25519 key and publishes the ciphertext using GATT
+
+2) the client decrypts it and uses it as a key for aes-ccm encrypting the
+wifi password
+
+3) the device decrypts that and, if successful, stores the secret
+
+
+
+https://docs.espressif.com/projects/rust/esp-hal/1.0.0-beta.0/esp32c3/esp_hal/aes/struct.Aes256.html
+
+this does not seem to expose any aes mode that has both encryption and
+message authenticity
+
+https://docs.rs/aes-ccm/latest/aes_ccm/
+
+this is software, but that's ok for what's probably quite a rare operation
+
+
+
+
+without a secon