What is in a Plug & Charge certificate?

A subject with the eMAID, an issuer, a validity period, a public key and the issuer's signature, chained through the provider's sub-CAs to a V2G root the charger trusts. The deep dive prints one chain and the four checks the backend runs on it.

Explained in

Plug & Charge · Deep diveThe two certificate chains of one sessionThe certificates behind the 11:20 AM session, as a tool prints them: the contract certificate chain the car presented, the checks the charger's backend ran, and the charger's own certificate from the TLS handshake.
  • Chain. Every signature verifies with the key of the certificate above, up to a root on the trust list. Fails when the car's root is unknown to the charger: the trust problem of stop 06.
  • Validity. No certificate in the chain has expired. Fails when the car missed its renewal, often after months without a session.
  • Status. The provider's responder says the contract is not revoked. Fails for ended contracts and stolen cars; offline, the charger decides by its local list.
  • Possession. The car signs the charger's challenge with the private key. Fails for a copied certificate; this is the check that makes the certificate a key and not a password.
From “Four checks, four failures that each stop a session”, stop 09

Terms

  1. eMAIDThe contract ID of an e-mobility contract, carried in the contract certificate for Plug & Charge.
  2. Trust listA list of root authorities that cars and chargers accept, so certificate chains from different authorities work together.
  3. V2GVehicle to grid: the car feeds energy into the public grid, usually through an aggregator or supplier.
  1. How does Plug & Charge work?The car carries a contract certificate and presents it to the charger over the cable. The backend checks it, and charging starts without a card or app.
  2. Who issues Plug & Charge certificates?Certificate authorities that operate V2G roots, with trust lists that let several roots work together. CharIN coordinates governance but does not operate a PKI.
  3. Why does Plug & Charge not work at every charger?Car, charger, backend, contract and trust all have to support it. If one is missing, the session starts with a card or app instead.
  4. What is ISO 15118-20?The second generation of ISO 15118, published in 2022. It adds bidirectional power transfer, wireless communication and automatic connection; a 2026 amendment adds megawatt charging and grid services.