Mark,
support for HTTPS will help but not be a 100% protection
against MITM attacks.
Regarding code signing, I think we don't need the ESP32
chip level protection, the primary concern is malicious
downloads / uploads.
So we could store the public key in the firmware instead
and use that to verify all downloads & uploads. That
way, anyone can create his/her own key pair to use for
personal builds.
Installing a firmware with another key would still be
possible by flashing via USB or SD.
Regards,
Michael
Am 07.04.2018 um 08:03
schrieb Mark Webb-Johnson:
Not at the moment.
From my understanding, there are two ways
to do this (not mutually exclusive):
- Signed firmware
This is the most comprehensive way. It involved a
public key stored on the OVMS module itself
(burned into e-fuses), and a private key used to
sign binaries. The boot loader will then refuse to
load any App who’s signature doesn’t match. Works
with flash encryption as well.
The problem with this is it conflicts with the
nature of open source. Once an ESP32 chip is put
in that mode, it will only execute code signed
with that private key. We can’t make that public
(without destroying the entire security).
- HTTPS
This at least provides some protection. We can
validate the SSL certificate of the server (api.openvehicles.com)
and protect somewhat from man-in-the-middle
attacks.
It doesn’t protect against other side-load attacks
(such as SD CARD firmware load) - but those
require physical access which is pretty much game
over anyway, right?
I would like to do #2, and made allowance
for that with ‘ota flash http’ leaving room for ‘ota
flash https’. Just our http client library is pretty
crappy at the moment, and it will take some effort to
make it support https.
Regards, Mark.
I don’t
have the full context for this discussion,
but I’m wondering: is the OTA update
mechanism protected against a
man-in-the-middle attack?
Tom
I
fixed it, and it should be ok now.
Mark,
the server check for an OTA
update now fails every time,
times out after 10 seconds.
I think that's because the new
server currently does a
redirect from http to https
also on the api.openvehicles.com host.
Not sure why the module
doesn't fail
directly on that, maybe it
tries to validate the
certificate which also does
not match.
As the openvehicles server has
frequent connectivity issues
from here I've added a
"nocheck" option to the ota
status command and use that
for the standard web
status page. The OTA page
still checks for the update.
Regards,
Michael
--
Michael Balzer * Helkenberger
Weg 9 * D-58256 Ennepetal
Fon 02333 / 833 5735 * Handy
0176 / 206 989 26
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