AES与RSA算法优化及其混合加密体制

Optimization of AES and RSA algorithm and its mixed encryption system

针对AES密钥扩展过程存在的安全隐患,提出一种改进的密钥扩展方法。针对轮函数中列混合和逆列混合运算耗时相差较大的问题,找出有限域GF(28)上最简形式的列混合和逆列混合运算,使其在加解密过程中消耗同样的运算资源;RSA方面,针对其运算效率的缺陷,将传统双素数变为四素数,在签名(解密)过程中,采用中国剩余定理结合蒙哥马利模乘来优化大数的模幂运算。在此基础上,结合两种算法的优点,并采用消息摘要、数字签名、数字信封等技术构建了一个既方便密钥管理又确保加密解密效率的混合加密体制。实验结果表明优化后的算法在运算速度上有一定优势并且有较高的可行性。

In order to overcome AES key expansion＇ s safety problem, this paper proposed a new key expansion method and used the simplest MixColumn and inverse MixColumn operation on GF（2s） to replace the former. In aspect of RSA,this paper suggested a four prime RSA with Chinese remainder theorem and Montgomery algorithm to improve the computing efficiency. Then it proposed a mixed encryption system and created a high security communicating model. Experiments show that advanced algorithm is faster than the original and mixed system has higher practicability.