Denial-of-Service (DoS) threats pose a major challenge to the idea of physical-layer key generation as the underlying wireless channels for key extraction are usually public. Identifying this vulnerability, we study the effect of DoS threats on relay-assisted key generation, and show that a reactive jamming attack on the distribution phase of relay-assisted key generation can forbid the nodes from extracting secret keys. To circumvent this problem, we propose a self-sustainable key generation model, wherein a frequency-hopping based distribution phase is employed to evade the jamming attack even though the participating nodes do not share prior credentials. A salient feature of the idea is to carve out a few bits from the key generation phase and subsequently use them to pick a frequency band at random for the broadcast phase. Interesting resource-allocation problems are formulated on how to extract maximum number of secret bits while also being able to evade the jamming attack with high probability. Tractable low-complexity solutions are also provided to the resource-allocation problems, along with insights on the feasibility of their implementation in practice.

翻译：拒绝服务（DoS）威胁对物理层密钥生成理念构成了重大挑战，因为用于密钥提取的底层无线信道通常是公开的。针对这一漏洞，我们研究了DoS威胁对中继辅助密钥生成的影响，并表明对中继辅助密钥生成分发阶段的反应式干扰攻击会阻止节点提取秘密密钥。为解决该问题，我们提出了一种自我可持续的密钥生成模型，其中采用基于跳频的分发阶段来规避干扰攻击，即便参与节点间未共享先验凭证。该方法的一个显著特征是从密钥生成阶段切分出少量比特，随后用于随机选择广播阶段的频带。我们提出了有趣的资源分配问题，探讨如何在以高概率规避干扰攻击的同时，提取最大数量的秘密比特。针对这些资源分配问题，我们提供了可处理的低复杂度解决方案，并深入分析了其实施的可行性。