In this paper we provide a theoretical argument towards an unsolved question related to Mantin’s “Digraph Repetition Bias” (Eurocrypt 2005) that is observed in the key-stream of RC4. The open question, that depends on the observation that arrival of four consecutive same bytes (of the form AAAA ) in RC4 key-stream is slightly negatively biased, was posed by Bricout et al (Des. Codes Cryptogr. 86:743–770, 2018) in 2016. Moreover, for the first time, we consider the “Reverse Digraph Repetition Bias” and show that there is significant negative bias in arrival of ABBA ( A , B two distinct bytes) in RC4 key-stream.

中文翻译：

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进一步澄清 RC4 中 Mantin 的有向图重复偏差

在本文中，我们针对在 RC4 的密钥流中观察到的与 Mantin 的“Digraph Repetition Bias”（Eurocrypt 2005）相关的未解决问题提供了理论论证。Bricout 等人 (Des. Codes Cryptogr. 86:743–770, 2018) 在 2016 年。此外，我们第一次考虑了“反向有向图重复偏差”，并表明在 RC4 密钥流中 ABBA（A，B 两个不同字节）的到达存在显着的负偏差。