Lightweight session key agreement schemes are expected to play a central role in building Internet of things (IoT) security in sixth-generation (6G) networks. A well-established approach deriving from the physical layer is a secret key generation (SKG) from shared randomness (in the form of wireless fading coefficients). However, although practical, SKG schemes have been shown to be vulnerable to active attacks over the initial “advantage distillation” phase, throughout which estimates of the fading coefficients are obtained at the legitimate users. In fact, by injecting carefully designed signals during this phase, a man-in-the-middle (MiM) attack could manipulate and control part of the reconciled bits and thus render SKG vulnerable to brute force attacks. Alternatively, a denial of service attack can be mounted by a reactive jammer. In this paper, we investigate the impact of injection and jamming attacks during the advantage distillation in a multiple-input–multiple-output (MIMO) system. First, we show that a MiM attack can be mounted as long as the attacker has one extra antenna with respect to the legitimate users, and we propose a pilot randomization scheme that allows the legitimate users to successfully reduce the injection attack to a less harmful jamming attack. Secondly, by taking a game-theoretic approach we evaluate the optimal strategies available to the legitimate users in the presence of reactive jammers.

中文翻译：

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保护物理层秘密密钥生成免受主动攻击

轻量级会话密钥协商方案有望在第六代 (6G) 网络中构建物联网 (IoT) 安全性方面发挥核心作用。一种源自物理层的成熟方法是从共享随机性（以无线衰落系数的形式）生成密钥 (SKG)。然而，尽管实用，但 SKG 方案已被证明在初始“优势蒸馏”阶段容易受到主动攻击，在整个过程中，在合法用户处获得衰落系数的估计值。事实上，通过在此阶段注入精心设计的信号，中间人 (MiM) 攻击可以操纵和控制部分协调位，从而使 SKG 容易受到暴力攻击。或者，拒绝服务攻击可以由反应性干扰器发起。在本文中，我们研究了多输入多输出 (MIMO) 系统中优势蒸馏过程中注入和干扰攻击的影响。首先，我们表明只要攻击者相对于合法用户有一个额外的天线，就可以发起 MiM 攻击，并且我们提出了一种导频随机化方案，允许合法用户成功地将注入攻击减少到危害较小的干扰攻击。其次，通过采用博弈论的方法，我们评估了存在反应性干扰器时合法用户可用的最佳策略。我们表明只要攻击者相对于合法用户有一个额外的天线，就可以发起 MiM 攻击，并且我们提出了一种导频随机化方案，允许合法用户成功地将注入攻击减少到危害较小的干扰攻击。其次，通过采用博弈论的方法，我们评估了存在反应性干扰器时合法用户可用的最佳策略。我们表明只要攻击者相对于合法用户有一个额外的天线，就可以发起 MiM 攻击，并且我们提出了一种导频随机化方案，允许合法用户成功地将注入攻击减少到危害较小的干扰攻击。其次，通过采用博弈论的方法，我们评估了存在反应性干扰器时合法用户可用的最佳策略。