We consider the strong secret key (SK) agreement problem for the satellite communication setting, where a satellite chooses a common binary phase shift keying modulated input for three statistically independent additive white Gaussian noise measurement channels whose outputs are observed by two legitimate transceivers (Alice and Bob) and an eavesdropper (Eve), respectively. Legitimate transceivers have access to an authenticated, noiseless, two-way, and public communication link, so they can exchange multiple rounds of public messages to agree on a SK hidden from Eve. Without loss of essential generality, the noise variances for Alice's and Bob's measurement channels are both fixed to a value $Q>1$, whereas the noise over Eve's measurement channel has a unit variance, so $Q$ represents a channel quality ratio. We show that when both legitimate transceivers apply a one-bit uniform quantizer to their noisy observations before SK agreement, the SK capacity decreases at least quadratically in $Q$.

翻译：我们考虑了卫星通信环境的强烈秘密钥匙(SK)协议问题。 卫星选择了一个普通的二进制转换键盘输入,用于三个统计独立的添加式白高斯噪音测量频道,其输出结果分别由两个合法的收发器(Alice和Bob)和一个窃听器(Eve)观测。 合法收发器可以访问一个经认证的无噪音、双向和公共通信链接,这样他们就可以交换多轮公开信息,以商定从夏娃隐藏的SK。 在不丧失基本的一般性的情况下,Alice和Bob的测量频道的噪音差异都固定在1美元的价值上,而Eve的测量频道上的噪音则有一个单位差异,因此$Q代表频道质量比率。 我们表明,当合法的收发器在SK协议之前对热量观测应用一比一致的四重器时,SK的容量至少以美元方位下降。