We study the fundamental limits of covert communications over general memoryless additive-noise channels. Under mild integrability assumptions, we find a general upper bound on the square-root scaling constant, which only involves the variance of the logarithm of the probability density function of the noise. Furthermore, we show that under some additional assumptions, this upper bound is tight. We also provide upper bounds on the length of the secret key required to achieve the optimal scaling.

翻译：我们研究了一般无记忆加性噪声信道上隐蔽通信的基本极限。在温和的可积性假设下，我们找到了平方根尺度常数的通用上界，该上界仅涉及噪声概率密度函数对数的方差。此外，我们证明在某些附加假设下，该上界是紧的。我们还给出了实现最优尺度所需的密钥长度的上界。