publication . Master thesis . 2016

Design and Analysis of a secure multi-party communication protocol

Herberth, Klaus;
Open Access English
  • Published: 01 Jan 2016
  • Country: Germany
Abstract
In the past years digital communication became an important aspect in every day life. Everything is shared and discussed in groups of friends, family or business part- ners without a proper way to protect that information. This master thesis introduces the first secure robust multi-party communication protocol which mimics a physical conversation with the help of a Diffie-Hellman key tree and social behaviours. Robust- ness against offline group members is reached by taking advantage of transitive trust between people and the ability to decline new members through an implicit protest. After introducing and analysing this new protocol, an improved version, which ...
Subjects
free text keywords: ddc:004
Related Organizations

1. Introduction 1 1.1. Why encrypted group communication? . . . . . . . . . . . . . . . . . . 1 1.2. Why another protocol? . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.3. Idea and Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2. Protocol Principles 5 2.1. Key Exchange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2. Encryption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.3. Implicit Agreement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.4. Message Authentication . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.5. Participant Awareness . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.6. History Awareness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3. Solution Design 11 3.1. Joining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.2. Exchanging data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3.3. Leaving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

4. Analysis 19 4.1. Adversaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 4.2. Information Disclosure . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 4.3. Message Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4.4. Key Exchange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 4.5. Message Authentication . . . . . . . . . . . . . . . . . . . . . . . . . . 22 4.6. Conceptual Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

5. Improved Protocol Version 29 5.1. Key exchange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 5.2. Veri cation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 5.3. Miscellaneous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

6. Future work & Conclusion 37 6.1. Future work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 6.2. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

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