The Distributed Symmetric Key Exchange (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.

翻译：分布式对称密钥交换（DSKE）协议允许两个无需事先接触的诚实方，通过各自安全共享机密数据的中间方实现安全秘密交换（例如密钥交换）。我们在Maurer的构造性密码学框架下展示了DSKE协议的可组合安全性。具体而言，我们证明了该协议在面对任意计算能力无界且可能完全攻破有限数量中间方并窃听全部通信的攻击者时，具有安全性（正确性与机密性）和鲁棒性。由于DSKE在无距离限制的网络场景中具备高度可扩展性，它有望成为一种经济高效的量子安全密码方案，用于抵御量子计算机对网络安全的威胁。