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OpenChargingCloud / ChargyDesktopApp

The Chargy E-Mobility Transparency Application for Windows, Mac OS X and Linux (based on Electron)
GNU Affero General Public License v3.0
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general flow #47

Open Gior80 opened 4 years ago

Gior80 commented 4 years ago

I have a question or need help

hello, come across this implementation and would like to ask you if you can explain more about general works as documentation is actually low.

In particular I cannot understand how data has to be certified and in which format ( all chargepoint uses different format? ) and what exactly the charging station need to create at the end of session to create the certified data.

For my understanding the software simply read a signed file sent from the station ( but I could be wrong) . So if have time can u better explain me this flow ?

Thanks !

ahzf commented 4 years ago

Hi,

yes, every charging station vendor or at least every smart meter vendor does it a bit different. Therefore, we created this software to abstract all the different ways to put a digital signature on measurement data.

The basic workflow for most vendors is:

  1. The charging process begins
  2. The meter is asked to measure and sign the current meter value, timestamp, user/process identification and some meta data
  3. ... charging ...
  4. The charging process stops
  5. The meter is asked again to measure and sign the current meter value, timestamp, user/process identification and some meta data

So now you have two signed meter data values and you are done. A simple example is here: https://github.com/OpenChargingCloud/ChargyDesktopApp/blob/v1.1/documentation/Alfen/ALFEN-Testdatensatz-10.chargy

The end customer receives the signed meter data from its EMP (or from the CPO) and now can load this data into Chargy. All it does is recognizing the correct data format and verifying that the signatures on the signed meter data and some additional data consistency checks are okay. If yes, you see a green checkmark, or multiple, as end customers do not want to verify every single charging process, but all processes of an entire month or year or so.

Chargy also supports to verify the public keys of the smart meters via certificates and to add multiple digital signatures on the data, which is useful if e.g. the charging station is only signing the meter data, but pricing and location information for the charging process are added and signed within the CPO backend. So, you can ensure, that the entire "charge transparency record" is valid.

I hope this helped you a little big. If you have more questions, feel free to ask :)