Towards a more secure and scalable verifying PKI of eMRTD

The new electronic passport stores biometric data on a contactless readable chip to uniquely link the travel document to its holder. This sensitive data is protected by a complex protocol called Extended Access Control (EAC) against unlawful readouts. EAC is manifold and thus needs a complex public key infrastructure (PKI). Additionally EAC is known to suffer from unsolved weaknesses, e.g., stolen (mobile) passport inspection systems due to its missing revocation mechanism. The article at hand seeks for potential approaches to solve these shortcomings. As a result we present an evaluation framework with special focus on security and scalability to assess the different candidates and to give a best recommendation. Instead of creating new protocols, we focus on solutions, which are based on well-known protocols from the Internet domain like the Network Time Protocol (NTP), the Online Certificate Status Protocol (OCSP), and the Server-based Certificate Validation Protocol (SCVP). These protocols are openly standardised, thoroughly tested, interoperable, and with the exception of SCVP all widely deployed. In addition to these Internet protocols we evaluate state-of-the-art security protocols proposed by the scientific community, e.g., the Hoepman protocol, the BioPACE V2 protocol and the On-line Secure E-Passport Protocol (OSEP). Our recommendation is that the EU EAC PKI would benefit most from introducing NTP and OCSP, or if fine-grained access control of EAC are considered dispensable by introducing the BioPACE V2 protocol.