Subject: Re: [its] does MANET or ITS scope extend to EV charging stations

From: Alison Chaiken <[email-masked]>
Date: Wed, 24 Apr 2013 08:02:53 -0700

*Michael Richardson asks:*
I didn't know that the CAN buses were directly bridged!!! I

The bridging of CAN is general in internal-combustion vehicles in order
that "smog tests" can be performed via the OBDII (SAE J1939) connector.
 Also, more generally, any information that is displayed on the instrument
cluster comes from a connection of a sensor (most likely via a gateway) to
the instrument cluster.    Historically, the whole network has been CAN but
recently the industry is moving, piecemeal, to FlexRay and then to
EthernetAVB.    The transition will take years, but we may hope that new
vehicles like plug-in ones will exclusively support the newer protocols,
which have more security.      CAN is intrinsically insecure at the Link
level, as it uses a CDMA/priority-arbitration scheme without authentication
or addressing.     Since CAN really is a Link-level protocol, layers above
it may implement more security -- or not!

Automotive networks inside the car have been conformant to the SAE
protocols and also ISO to some extent.    Unfortunately, there are at least
as many internal network protocols as the external ones we've been
discussing.
*
Michael Richardson asks:*
Is there a specification for the charging cable that is publically
available?

The industry-standard charging plug is governed by SAE-J1772.
 Unfortunately Tesla, one of the market leaders, has chosen an incompatible
plug for its newer vehicles.

*Note: *I am not quoting hundreds of lines of other's postings at the end
of this message.    Please considering keeping message text brief in this
fashion by excepting previous messages rather than wholesale inclusion of
them!    Thanks in general for the informative discussion on this list.

-- 
Alison Chaiken                           [email-masked]
650-279-5600                            http://{she-devel.com,
exerciseforthereader.org}
The intermediary between the head and the hands must be the heart.    --
Thea von Harbou

---

From: Michael Richardson <[email-masked]>
Date: Thu, 25 Apr 2013 15:00:39 -0400

mcr> I didn't know that the CAN buses were directly bridged!!! I

>>>>> "Alison" == Alison Chaiken <[email-masked]> writes:
    Alison> The bridging of CAN is general in internal-combustion
    Alison> vehicles in order that "smog tests" can be performed via the
    Alison> OBDII (SAE J1939) connector. 

Yeah, I can get that when I go to the garage, that they want access to
the internals of the system. No different than disrobing for the doctor.

    Alison> which have more security.      CAN is intrinsically insecure
    Alison> at the Link level, as it uses a CDMA/priority-arbitration
    Alison> scheme without authentication 
    Alison> or addressing.     Since CAN really is a Link-level
    Alison> protocol, layers above 
    Alison> it may implement more security -- or not!

Yes, I knew if bad guy could access it physically, the bad guy has won,
which is why I'm surprised to learn that some plug-in cables have CAN
according to the slides you posted.

    mcr> Is there a specification for the charging cable that is publically
    mcr> available?

    Alison> The industry-standard charging plug is governed by SAE-J1772.
    Alison> Unfortunately Tesla, one of the market leaders, has chosen
    Alison> an incompatible 
    Alison> plug for its newer vehicles.

okay, thanks for this.
Did Tesla explain why they didn't use that plug?

I'm a bit surprised that AC is transmitted, as that seems to move lots
of heavy equipment into the car and forces alternative generation system
to make AC just for the car to turn it back into DC to charge the
batteries.

wikipedia says:
	  "SAE is developing a Combo Coupler variant of the J1772
	  connector with additional pins to accommodate fast DC charging
	  at 200-450 Volts DC and up to 90 kW."

it also mentions the "GreenPHY" PLC protocol.... oh a form of ethernet
over powerline.  would that run over the primary power supply, or
somewhere else?  If the AC isn't turned on yet, how can the system
negotiate turning the AC on using GreenPHY?

The stock/legacy signaling protocol seems to be based upon switching
resistors... ick. 

-- 
]               Never tell me the odds!                 | ipv6 mesh networks [ 
]   Michael Richardson, Sandelman Software Works        | network architect  [ 
]     [email-masked]  http://www.sandelman.ca/        |   ruby on rails    [