Kaufmann, StefanKlenk, HerbertKeller, Hubert B.Plödereder, ErhardDencker, Peter2017-06-302017-06-302015978-3-88579-634-3Car-2-Car communication requires the use of pseudonymous public keys to ensure the vehicle's privacy by making its messages unlinkable over a longer period. The Pseudonymous PKI (PPKI) for Ubiquitous Computing by K. Zeng [Ze06] offers peer-side pseudonym generation, non-repudiation and an efficient revocation mechanism that excludes the revoked peers from the group of authorized participants. In addition, this work provides a new authorisation scheme that incorporates efficiently into the pseudonymous PKI, offers peer-side pseudonymous credential generation and preserves the peer's privacy during the initial authorisation obtainment from third party authentication authorities. The PKI scheme is also supplemented with a particular non-pseudonymous variation for roadside units as well as other adaptations based on Car-2-Car requirements. Finally, the signature verification performance and message sizes are analysed. We argue that the PPKI fulfils the security challenges of Car-2-Car communication and has advantages over a classical PKI.enText/Conference Paper1617-5468