123

代码说明：

  首先对字母进行编号，小写字母a至z编号为1至26，大写字母A至Z分别编号27至52，这样每个字母都有唯一的一个序号，在发送内容时，我们以函数F(X)=X*X+X+1对发送字母的序号进行计算，就会获取个新的序号，对该序号再进行对52取余，该序号即为加密后的要发送字母的序号，这样就能达到加密的作用。(Number first letter lowercase letters a to z No. 1-26, No. 27-52 uppercase letters A to Z, respectively, so each letter has a unique serial number, sending content to the function F (X- ) = X* X+X+1 send letters number is calculated, it will get a new serial number, the serial number and then take the remainder of the 52, the serial number is the serial number of the letters to be sent encrypted, so that we can achieve encryption role.)