利用细胞自动机构造密钥流发生器

构造一个好的密钥流发生器一直是比较困难的问题，一方面需要保证密钥流具有较大的周期，另一方面，还要保证从一已知序列预测整个密钥流序列是很困难的，此外，还要考虑所构造的密钥流发生器有利于硬件实现。于是近几年，人们将公众多目光投向一细胞自动机，因为利用细胞机（CA）的很多特点可以构造出符合以上条件的密钥流发生器，文中精心构造了一种具有最大周期的二维细胞自动机，并在这种CA的基础上提出了两种构造密钥流发生器的方法。这两种密钥流发生器具有较大的，并具有较强的线性复杂性和相关免疫性，分析表明，这两种密钥流发生器具有足够的密码性能。

Keystream generator by cellular automata

Designing a good Keystream Generator is very difficult, because we must give assurance that the Keystream Generator should have a maximum cycle, and that an attacker cannot derive the whole stream from a part of the known stream. In addition, when designing a Keystream Generator, we hope it can be implemented with hardware easily. Many experts pay their attention to Cellular Automata(CA) in recent years, because the Keystream Generators by CA can meet the conditions. In this paper, we elaborately discuss the design of a kind of two dimension Cellular Automata, which has a maximum cycle, and introduce two Keystream Generators constructed by the two dimension CA. They have a maximum cycle, good Linear Complexity and Correlation Immunity. The Keystream Generators have good cipher performance.