Achieving Security Despite Compromise Using Zero-knowledge

One of the important challenges when designing and analyzing cryptographic protocols is the enforcement of security properties in the presence of compromised participants. This paper presents a general technique for strengthening cryptographic protocols in order to satisfy authorization policies despite participant compromise. The central idea is to automatically transform the original cryptographic protocols by adding non-interactive zero-knowledge proofs. Each participant proves that the messages sent to the other participants are generated in accordance to the protocol. The zero-knowledge proofs are forwarded to ensure the correct behaviour of all participants involved in the protocol, without revealing any secret data. We use an enhanced type system for zero-knowledge to verify that the transformed protocols conform to their authorization policy even if some participants are compromised. Both the protocol transformation and the verification are fully automated.

• Type: Conference
• Year: 2009
• Where: CSFW
• Authors: Michael Backes, Martin P. Grochulla, Catalin Hritcu, Matteo Maffei
• Keywords: Cryptographic Protocols, CSFW 2009, Non-interactive Zero-knowledge Proofs, Security Privacy, Zero-knowledge Proofs