We discuss the operational meaning of a commonly accepted security parameter in quantum key distribution, which is based on the trace distance. We separately consider the cases of using a key in a one-time pad and in a computationally secure cipher. Some practical aspects of using the security parameter are also elucidated, which are usually not paid enough attention in theoretical studies and which therefore may cause difficulties for experimentalists and engineers. It is shown that a one-time pad requires not only a higher key generation rate than computationally secure ciphers, but also a significantly stronger condition on the key security parameter.

中文翻译：

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在量子密钥分发中使用安全参数的操作意义和实践方面

我们讨论了基于跟踪距离的量子密钥分发中普遍接受的安全参数的操作含义。我们分别考虑在一次性密码和计算安全密码中使用密钥的情况。还阐明了使用安全参数的一些实际方面，这些方面在理论研究中通常没有得到足够的重视，因此可能会给实验人员和工程师带来困难。结果表明，一次一密不仅需要比计算安全密码更高的密钥生成率，而且还需要对密钥安全参数有更强的条件。