hey wanna read some horrors? https://www.w3.org/TR/exi/
Efficient XML Interchange (EXI) Format 1.0 (Second Edition)

@whitequark
The real horror is that #EXI is used in an ISO 15118 sandwich on top of HomePlug AV (with broken encryption) and TCP (mostly with no encryption, but sometimes mixed with a wild PKI) to real-time control up to a Megawatt of electric power flowing into a car.

#PowerLine #V2G #EV

@ge0rg aaahhhh

@whitequark
And to add to the horror, all of the cars and chargers are in the same physical powerline broadcast domain, so when another car is plugged in, it needs to broadcast ping and measure the response signal strength(*) to find out which charger it's connected to...

And once the data channel is up, you authorize the payment with the absolutely unforgeable and secret... *checks notes* serial number of your RFID card!

(*) SLAC (Signal Level Attenuation Characterization)

@ge0rg @whitequark yeah, I think one alternative had been “single wire CAN” over the control pilot pin, as used by Tesla Superchargers back then. 83kbps, bidirectional, the basics known by everyone in the industry, a pragmatic and completely sane solution for the problem of charging cars, with much future expandability to spare. Pretty much on point.

But then we came into the “design by committee” phase of EV charging, and now we have this fucking thing.

@vogelchr
But you can't do TLS PKI over 83kbit/s CAN!!111
@whitequark
@ge0rg @vogelchr you can't?
@whitequark
This is not a question of technical feasibility.
@vogelchr
@ge0rg @vogelchr let me rephrase: I'm curious what the argument presented against it was