Over-the-Air (OtA) computation is a newly emerged concept for computing functions of data from distributed nodes by taking advantage of the wave superposition property of wireless channels. Despite its advantage in communication efficiency, OtA computation is associated with significant security and privacy concerns that have so far not been thoroughly investigated, especially in the case of active attacks. In this paper, we propose and evaluate a detection scheme against active attacks in OtA computation systems. More explicitly, we consider an active attacker which is an external node sending random or misleading data to alter the aggregated data received by the server. To detect the presence of the attacker, in every communication period, legitimate users send some dummy samples in addition to the real data. We propose a detector design that relies on the existence of a shared secret only known by the legitimate users and the server, that can be used to hide the transmitted signal in a secret subspace. After the server projects the received vector back to the original subspace, the dummy samples can be used to detect active attacks. We show that this design achieves good detection performance for a small cost in terms of channel resources.

翻译：空中计算（OtA）是一种利用无线信道波叠加特性的新型分布式节点数据函数计算方法。尽管该方法在通信效率方面具有优势，但其伴随的安全与隐私问题尚未得到充分研究，特别是在主动攻击场景下。本文针对空中计算系统中的主动攻击，提出并评估了一种检测方案。具体而言，我们考虑外部节点通过发送随机或误导性数据来篡改服务器接收的聚合数据的主动攻击者。为检测攻击者存在，合法用户在每次通信周期中除发送真实数据外还额外发送虚拟样本。我们提出了一种检测器设计方案，该方案依赖于仅合法用户与服务器知晓的共享密钥，可将传输信号隐藏在秘密子空间中。当服务器将接收向量投影回原始子空间后，利用虚拟样本即可检测主动攻击。研究表明，该方案以较低的通道资源成本实现了良好的检测性能。