本文根据PKCS(Public Key Cryptosystem)中大数运算的特点,提出了一套模运算的双表算法,并基于数论理论,就该算法的基础及其复杂性给出了完善的证明。整套算法的基本思想是:以空间换取时间。其建预表的递推方法大大地提高了建表效率,并且两个表都直接参与模运算,显著地提高了运算效率。 According to the characteristics of large number operations in PKCS (Public Key Cryptosystem), this paper presents a set of modular arithmetic double table algorithm, and based on number theory, gives a complete proof of the basis and complexity of the algorithm. The basic idea of ​​the entire algorithm is: in exchange for space time. The recursive method of building a table has greatly improved the efficiency of building a table, and both tables are directly involved in the modular operation, which significantly improves the operation efficiency.