A fundamental threat to quantum cryptography: gravitational attacks

An attack on the ``Bennett-Brassard 84''(BB84) quantum key-exchange protocol in which Eve exploits the action of gravitation to infer information about the quantum-mechanical state of the qubit exchanged between Alice and Bob, is described. It is demonstrated that the known laws of physics do not allow to describe the attack. Without making assumptions that are not based on broad consensus, the laws of quantum gravity, unknown up to now, would be needed even for an approximate treatment. Therefore, it is currently not possible to predict with any confidence if information gained in this attack will allow to break BB84. Contrary to previous belief, a proof of the perfect security of BB84 cannot be based on the assumption that the known laws of physics are strictly correct, yet.Comment: Eur. Phys. J. D (2006), in prin

A new Definition and Classification of Physical Unclonable Functions

A new definition of "Physical Unclonable Functions" (PUFs), the first one that fully captures its intuitive idea among experts, is presented. A PUF is an information-storage system with a security mechanism that is 1. meant to impede the duplication of a precisely described storage-functionality in another, separate system and 2. remains effective against an attacker with temporary access to the whole original system. A novel classification scheme of the security objectives and mechanisms of PUFs is proposed and its usefulness to aid future research and security evaluation is demonstrated. One class of PUF security mechanisms that prevents an attacker to apply all addresses at which secrets are stored in the information-storage system, is shown to be closely analogous to cryptographic encryption. Its development marks the dawn of a new fundamental primitive of hardware-security engineering: cryptostorage. These results firmly establish PUFs as a fundamental concept of hardware security.Comment: 6 pages, 3 figures; Proceedings "CS2 '15 Proceedings of the Second Workshop on Cryptography and Security in Computing Systems", Amsterdam, 2015, ACM Digital Librar