Composable Security of Distributed Symmetric Key Establishment Protocol

TL;DR

This paper proves the composable security of a scalable, quantum-safe distributed key exchange protocol that maintains confidentiality even under full compromise of some intermediaries and adversarial eavesdropping.

Contribution

It establishes the security and robustness of the DSKE protocol within the constructive cryptography framework, including against unbounded adversaries with compromised intermediaries.

Findings

Proves correctness and confidentiality of DSKE

Demonstrates robustness against fully compromised intermediaries

Supports quantum-safe scalable network security

Abstract

The Distributed Symmetric Key Establishment (DSKE) protocol provides secure secret exchange (e.g., for key exchange) between two honest parties that need not have had prior contact, and use intermediaries with whom they each securely share confidential data. We show the composable security of the DSKE protocol in the constructive cryptography framework of Maurer. Specifically, we prove the security (correctness and confidentiality) and robustness of this protocol against any computationally unbounded adversary, who additionally may have fully compromised a bounded number of the intermediaries and can eavesdrop on all communication. As DSKE is highly scalable in a network setting with no distance limit, it is expected to be a cost-effective quantum-safe cryptographic solution to safeguarding the network security against the threat of quantum computers.