1978年就出现了这种算法，它是第一个既能用于数据加密也能用于数字签名的算法。 RSA的安全性依赖于大数难于分解这一特点。公钥和私钥都是两个大素数（大于100个十进制位）的函数。-In 1978 came the algorithm, it is the first can used for data encryption can also be used as a digital signature algorithm. The RSA security depends on the characteristics of large difficult to decomposition. Public and private key are two big primes (more than 100 decimal) function.