# Information Security and Cryptography Research Group

## A Calculus for Security Bootstrapping in Distributed Systems

### Ueli Maurer and Pierre Schmid

Journal of Computer Security, vol. 4, no. 1, pp. 55–80, 1996, Preliminary version: [MauSch94].

A calculus of channel security properties is presented which allows to analyze and compare protocols for establishing secure channels in a distributed open system at a high level of abstraction. A channel is characterized by its direction, its time of availability and its security properties. Cryptographic primitives as well as trust relations are interpreted as transformations for channel security properties, and a cryptographic protocol can be viewed as a sequence of such transformations. A protocol thus allows to transform a set of secure channels established during an initial setup phase, together with a set of insecure channels available during operation of the system, into the set of secure channels specified by the security requirements. The necessary and sufficient requirements for establishing a secure channel between two entities are characterized in terms of secure channels to be made available during the initial setup phase and in terms of trust relations between users and/or between users and trusted third parties.

Keywords: Network security, Distributed systems, Key management, Cryptography, Security transformations, Formal models.

## BibTeX Citation

@article{MauSch96,
author       = {Ueli Maurer and Pierre Schmid},
title        = {A Calculus for Security Bootstrapping in Distributed Systems},
journal      = {Journal of Computer Security},
pages        = 55--80,
number       = 1,
volume       = 4,
year         = 1996,
note         = {Preliminary version: \cite{MauSch94}},
}