Eichrecht - Transmission of data

In order to allow be.ENERGISED to show the user the validity of signed meter values, station need to send different type of information to the backend with in OCPP. Namely those are on the one hand the signed values itself and on the other hand the public keys, which are needed by the Transparenzsoftware to verify the transferred information. This information can be provided in different ways.

All embedded in the signed values

In OCPP 2.0.1 the protocol got much clearer on how to transfer public keys and signed values, as it introduced an extra datastructure for this. This is also the preferred way how signed values should be transferred in ocpp 1.6 with a small adaptions, where the value just contains the full object as in OCPP 2.0.1 suggested.

JSON Example

[
   2,
   "1234",
   "StopTransaction",
   {
      "reason":"Local",
      "transactionId":123,
      "meterStop":500,
      "timestamp":"2022-08-27T12:34:56.000Z",
      "transactionData":[
         {
            "sampledValue":[
               {
                  "unit":"Wh",
                  "context":"Transaction.End",
                  "format":"SignedData",
                  "location":"Outlet",
                  "measurand":"Energy.Active.Import.Register",
                  "value":"{\"signedMeterValue\":\"<base64 encoded OCMF string>\", \"encodingMethod\":\"OCMF\", \"publicKey\":\"<public key>\"}"
               }
            ],
            "timestamp":"2022-08-27T12:34:56.000Z"
         }
      ]
   }
]

SOAP Example

<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope" xmlns:ns="urn://Ocpp/Cs/2015/10/">
   <soap:Header>
      <ns:chargeBoxIdentity>ABCDEF12345</ns:chargeBoxIdentity>
   </soap:Header>
   <soap:Body>
      <ns:meterValuesRequest>
         <ns:connectorId>1</ns:connectorId>
         <ns:transactionId>1234567</ns:transactionId>
         <ns:meterValue>
            <ns:timestamp>2018-08-02T08:58:21Z</ns:timestamp>
            <ns:sampledValue>
               <ns:value>{"signedMeterValue":"<base64 encoded OCMF string>", "encodingMethod":"OCMF", "publicKey":"<public key>"}</ns:value>
               <ns:context>Transaction.Begin</ns:context>
               <ns:format>SignedData</ns:format>
               <ns:measurand>Energy.Active.Import.Register</ns:measurand>
            </ns:sampledValue>
         </ns:meterValue>
      </ns:meterValuesRequest>
   </soap:Body>
</soap:Envelope>

We further suggest, that all relevant values which should be checked by the Transparenzsoftware are sent as part of the StopTransactionRequest.

Currently all type of signed values which are supported in the Transparencysoftware (Versions: 1.0, 1.1, 1.2), are also supported by the backend.

[
   2,
   "1234",
   "StopTransaction",
   {
      "reason":"Local",
      "transactionId":123,
      "meterStop":500,
      "timestamp":"2022-08-27T12:34:56.000Z",
      "transactionData":[
         {
            "sampledValue":[
                {
                  "unit":"Wh",
                  "context":"Transaction.Start",
                  "format":"SignedData",
                  "location":"Outlet",
                  "measurand":"Energy.Active.Import.Register",
                  "value":"{\"signedMeterValue\":\"<base64 encoded OCMF string>\", \"encodingMethod\":\"OCMF\", \"publicKey\":\"<public key>\"}"
               },
               {
                  "unit":"Wh",
                  "context":"Transaction.End",
                  "format":"SignedData",
                  "location":"Outlet",
                  "measurand":"Energy.Active.Import.Register",
                  "value":"{\"signedMeterValue\":\"<base64 encoded OCMF string>\", \"encodingMethod\":\"OCMF\", \"publicKey\":\"<public key>\"}"
               }
            ],
            "timestamp":"2022-08-27T12:34:56.000Z"
         }
      ]
   }
]

If the station is not following this suggestion, the backend will still try to parse on the transferred data and will treat the string defined in value of the MeterValue object as a signed value. With this setup though the station needs to send the public key via different way.

Additional options to send a public key

In addition to the suggestion above, the backend will also understand the submission of public keys with a custom DataTransfer message.

setMeterConfiguration (Public key transfer)

Key	Type	Description
connectorId	int (required)	connectorId according to the OCPP specification
meterSerial	string (optional)	Serialnumber of the meter connected to this public key
type	string (required)	Defined the type of conformity (see list below)
publicKey	string (optional)	Actual public key hex encoded (necessary if type is set to SIGNATURE)

The different types derive from different possibilities on how the conformity is reached. Following types are currently allowed

Type passed in meter configuration

Type	Description
SIGNATURE	Station will transmit signed values to the backend
LOCAL	Only local (local on the station) via visibility on the station itself (Note that this cannot be automatically ensured by the backend then)

SOAP Example

<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope" xmlns:ns="urn://Ocpp/Cs/2015/10/">
   <soap:Header>
      <ns:chargeBoxIdentity>ABCDEF12345</ns:chargeBoxIdentity>
   </soap:Header>
   <soap:Body>
      <ns:DataTransferRequest>
         <ns:vendorId>generalConfiguration</ns:vendorId>
         <ns:messageId>setMeterConfiguration</ns:messageId>
         <ns:data>{"meters":[{"connectorId":1,"meterSerial":"123456789","type":"SIGNATURE","publicKey":"887FABF407AC82782EEFFF2220C2F856AEB0BC22364BBCC6B55761911ED651D1A922BADA88818C9671AFEE7094D7F536"}]}</ns:data>
      </ns:DataTransferRequest>
   </soap:Body>
</soap:Envelope>

JSON Example

{
  "vendorId": "generalConfiguration",
  "messageId": "setMeterConfiguration",
  "data": "{\"meters\":[{\"connectorId\":1,\"meterSerial\":\"123456789\",\"type\":\"SIGNATURE\",\"publicKey\":\"887FABF407AC82782EEFFF2220C2F856AEB0BC22364BBCC6B55761911ED651D1A922BADA88818C9671AFEE7094D7F536\"}]}"
}