CROSSING Guest Talk: Prof. Dr. Amir Herzberg

Topic: Provable Security for PKI Schemes – and the (Composable) Modular Security Specifications Framework

2024/04/16 11:00-12:00

Location: TU Darmstadt, Pankratiusstraße 2 (S2|20, 9)



PKI schemes provide a critical foundation for applied cryptographic protocols. However, there are no rigorous security specifications for realistic PKI schemes, and therefore, no PKI schemes were proven secure. Cryptographic systems that use PKI are analyzed by adopting overly simplified models of the PKI, often, simply assuming secure public keys. This is problematic considering the extensive reliance on PKI, the multiple failures of PKI systems, and the fact that proposed and deployed PKI are complex, have complex requirements and assume complex models.

We present game-based security specifications for PKI schemes, and analyse important, widely deployed PKIs: PKIX and two variants of Certificate Transparency (CT). All PKIs are based on the X.509v3 standard and its CRL revocation mechanism. Our analysis identified few subtle vulnerabilities, and includes reduction-based proofs showing that the PKIs ensure specific requirements under specific models (assumptions).To our knowledge, this is the first reduction-based definition and proof of security for a realistic PKI scheme.

Our specifications and analysis use the Modular Security Specifications (MoSS) framework [Crypto'21]. The talk will explain the relevant aspects of MoSS. We may briefly discuss the extensions that allow provably-secure compositions of protocols.

Joint work with Sara Wrotniak, Hemi Leibowitz and Ewa Syta.

Speaker Bio

Dr Herzberg is the Comcast Professor for Cybersecurity Innovation in the School of Computing at the University of Connecticut. His research areas include Internet security, applied cryptography, privacy and anonymity, usable security, security for cyber-physical systems, and social, economic, and legal aspects of security.

Dr Herzberg received his Ph.D. in Computer Science from the Technion in Israel in 1991. From 1991 to 1995, he worked at the IBM T.J. Watson Research Center, where he was a research staff member and manager of the Network Security research group. From 1996 to 2000, Dr Herzberg was manager of e-business and security technologies at the IBM Haifa Research Lab. From 2002 to 2017, he was a professor at Bar Ilan University (Israel). Since 2017, he has been a professor at the University of Connecticut.