中文摘要：

针对多层可逆元胞自动机（LRCA）加密算法密钥空间小且结构简单的问题，该文提出了一种改进可逆多层元胞自动机（ILRCA）分组加密算法。将4个初等可逆规则标记后，在每轮迭代前生成关于规则的伪随机序列作为密钥，并引入移位变换，达到了一次一密的加密效果，且有效地扩充了密钥空间。实验结果表明，伪随机序列和移位变换的引入，使得该文算法中任一位明文的改变都引起超过50%的密文变化，与高级加密标准（AES）和 LRCA 相比较，加密速度快、扩散效果更好。

英文摘要：

Aiming at the problems of small key space and simple structure of the layered and reversible cellular automata（ LRCA） encryption algorithm,a block encryption algorithm based on improved layered and reversible cellular automata （ ILRCA） is proposed here. Four elementary reversible rules are marked. Random sequences concerning the rules are generated as keys before each iteration,and shift transformation is used in each iteration achieving one-time pad and enlarging the key space. The experimental results indicate that using random sequences and shift transformation,more than half bits of the ciphertext may change when a single bit of the plaintext is changed;compared with the advanced encryption standard（AES） and LPCA encryption algorithm, the encryption algorithm proposed here has faster encryption speed and better diffusion effect.