Strand spaces and rank functions:more than distant cousins

Abstract

We show that for rigid symmetric top molecules in electric fields the phenomenon of monodromy arises naturally as a ''defect'' in the lattice of quantum states in the energy-momentum diagram. This makes it impossible to use either the total angular momentum or a pendular quantum number to label the states globally. The monodromy is created or destroyed by classical Hamiltonian Hopf bifurcations from relative equilibria. These phenomena are robust and should be observable in quasi-symmetric top molecules with field strengths E satisfying E/bϾ4.5, where is the dipole moment and b the rotational constant perpendicular to the symmetry axis of the molecule.

Secrecy Analysis in Protocol Composition Logic

“…In this section we use the proof system developed in section 3 to prove a secrecy property of a simple variant N SLV AR of the Needham-Schroeder-Lowe protocol, proposed in [16], in which parties A and B use an authenticated temporary secret na to establish a secret key k that is in turn used to protect the actual message m. The main difference from the original NSL protocol is that the initiator's nonce is leaked in the final message. Reasoning from A's point of view, nonce na should be secret between A and B at the point of the run in the protocol where A is just about to send the last message.…”

“…For example, within CSP, properties of messages that may appear on the network have been identified by defining a rank function [18,16], with an inductive proof used to show that rank is preserved by the attacker actions and all honest parties. In comparison, arguments in our formal logic use a conjunction involving the SafeNet predicate and protocol specific properties Φ in our inductive hypotheses.…”

“…The straightforward formal proof in section 4 therefore shows that our method does not suffer from the limitations identified in [16]. Intuitively, the advantage of our setting lies in the way that modal formulas of PCL state properties about specific points in protocol execution, rather than only properties that must be true at all points in all runs.…”

“…Our first protocol example is a variant of the Needham-Schroeder protocol, used in [16] to illustrate a limitation of the original rank function method and motivate an extension for reasoning about temporary secrets. The straightforward formal proof in section 4 therefore shows that our method does not suffer from the limitations identified in [16].…”

Inductive Proofs of Computational Secrecy

“…We also extend previous composition theorems [16,21] to the present setting, and illustrate the power of the resulting system by giving modular formal proofs of authentication and secrecy properties of Kerberos V5 and Kerberos V5 with PKINIT. We are also able to prove properties of a variant of the Needham-Schroeder-Lowe protocol that are beyond the standard rank function method [22,19].…”