java实现仿射密码加密解密

import java.util.scanner;

public class affine{

  public static void main(string[] args) {

   char [] form = { 'a' , 'b' , 'c' , 'd' , 'e' , 'f' , 'g' , 'h' , 'i' , 'j' , 'k' , 'l' , 'm' , 'n' ,

     'o' , 'p' , 'q' , 'r' , 's' , 't' , 'u' , 'v' , 'w' , 'x' , 'y' , 'z' , '0'

     , '1' , '2' , '3' , '4' , '5' , '6' , '7' , '8' , '9' };

   scanner sc = new scanner(system.in);

   system.out.println( "请输入待加密的明文：" );

   string mingwen = sc.nextline();

   mingwen=mingwen.touppercase(); //将输入的明文全部大写

   final int k1 = 103 ;

   final int k2 = 103 ;

   final int k3 = 31 ;

   int [] ciphernum= new int [mingwen.length()]; //用来存储数字化的密文

   encryption(mingwen,form,k1,k2,ciphernum);

   decryption(form,mingwen,k2,k3,ciphernum);

  }

  public static void encryption(string mingwen, char [] form, int k1, int k2, int [] ciphernum){

   //第一步：将明文存入数组

   char [] pla= new char [mingwen.length()];

   for ( int i = 0 ; i <mingwen.length() ; i++) {

    pla[i]=mingwen.charat(i);

   } //已将明文存入字符数组pla中

   //第二步：通过脚标找到明文中每个字符对应的数，参与加密运算

   int [] mingwennumber= new int [pla.length];

   for ( int i = 0 ; i <pla.length ; i++) {

    for ( int j = 0 ; j <form.length ; j++) {

     if (form[j]==pla[i]) {

      mingwennumber[i] = j;

     }

    }

   }

   //通过脚标将明文全部转化为数字

   char [] cipher = new char [mingwen.length()]; //cipher密码数组 用来存储密文

   for ( int i = 0 ; i <mingwen.length() ; i++) {

    int a= math.floormod((k1*mingwennumber[i]+k2), 36 );

    ciphernum[i]=a;

    cipher[i]=form[a];

    //计算密文并存入数组中

   }

   system.out.println( "加密结果是：" );

   system.out.println(cipher);

  }

  public static void decryption( char [] form,string mingwen, int k2, int k3, int [] ciphernum){

   char [] jiemi= new char [mingwen.length()];

   for ( int i = 0 ;i<mingwen.length();i++){

    jiemi[i]=form[math.floormod(k3*(ciphernum[i]-k2), 36 )];

   }

   system.out.println( "解密结果是：" );

   system.out.println(jiemi);

  }

}