Physical layer security (PLS) is seen as the means to enhance physical layer trustworthiness in 6G. This work provides a proof-of-concept for one of the most mature PLS technologies, i.e., secret key generation (SKG) from wireless fading coefficients during the channel's coherence time. As opposed to other works, where only specific parts of the protocol are typically investigated, here, we implement the full SKG chain in four indoor experimental campaigns. In detail, we consider two legitimate nodes, who use the wireless channel to extract secret keys and a malicious node placed in the immediate vicinity of one of them, who acts as a passive eavesdropper. To estimate the final SKG rate we evaluate the conditional min-entropy by taking into account all information available to the eavesdropper. Finally, we use this paper to announce the first ever physical layer security challenge, mirroring practices in cryptography. We call the community to scrutinize the presented results and try to ``break'' our SKG implementation. To this end, we provide, i) the full dataset observed by the eavesdroppers and all algorithms used, ii) $20$ blocks of $16-$byte long ciphertexts, encrypted using AES-256 with $20$ distilled secret keys, and, iii) all codes and software used in our SKG implementation. An attack will be considered successful if any part(s) of the plaintext are successfully retrieved.

翻译：物理层安全（PLS）被视为增强6G物理层可信性的手段。本文为最成熟的PLS技术之一——利用信道相干时间内无线衰落系数进行密钥生成（SKG）提供了概念验证。与其他仅研究协议特定环节的工作不同，我们在四项室内实验活动中实现了完整的SKG链路。具体而言，我们考虑两个合法节点利用无线信道提取密钥，以及一个紧邻其中之一放置的恶意节点作为被动窃听者。为估算最终SKG速率，我们通过考虑窃听者可获取的全部信息，评估条件最小熵。最后，本文首次宣布物理层安全挑战赛，借鉴密码学领域的实践模式。我们呼吁学术界仔细审视所呈现的结果，尝试“破解”我们的SKG实现。为此，我们提供：i) 窃听者观测到的完整数据集及所用全部算法；ii) 使用20个蒸馏密钥经AES-256加密的20个16字节密文块；iii) 本SKG实现中使用的全部代码与软件。若能成功恢复明文任何部分，则视为攻击成功。