仿射密码加密解密 (输入字母数值)

 1  import java.util.*;
 2  public class FangSheMiMa{
 3      public static void main (String args[]){           
 4              System.out.println("请依次输入k1,k2,字母数值");             
 5              Scanner scan=new Scanner (System .in);
 6              int k1=scan.nextInt();
 7              int k2=scan.nextInt();
 8              int letter=scan.nextInt();
 9                        
10             if (gcd(k1,26)!=1){
11                 System.out.println("输入的密匙不符合要求!");
12             }
13             else{ 
14                      System .out.println("请选择操作");
15                      System .out.println("1:加密 ");
16                      System .out.println("2:解密 ");                      
17                      int t=scan.nextInt();
18                      switch (t ){
19                      case 1: 
20                          System .out.println("明文:"+ letter+"   "+jiaMi(letter,k1,k2));
21                          System .out.println("          ");
22                          break;
23                      case 2:                  
24                          System .out.println("密文:"+letter+"   "+jieMi(letter,k1,k2));
25                          System .out.println("          ");
26                          break;
27                                    
28                      }
29             }
30         }
31     /* }*/
32 
33  
34      private static int gcd(int k1, int n) {//  gcd(k1,n)=1为仿射密码具有可逆性的条件
35             // TODO Auto-generated method stub
36             int k=0;//
37             do{
38                 k=k1%n;
39                 k1=n;
40                 n=k;
41             }while(k!=0);
42                 return k1;             
43         }  
44      //辗转消除求最大公约数
45      private static int ni(int k1,int n){
46          int i=1;
47          while(k1*i%n!=1){
48              i++;
49          }
50         return i;
51      }
52      
53     //加密算法
54         private static String jiaMi(int plainText, int k1, int k2) {
55             // TODO Auto-generated method stub
56             //String PlainText="";
57             int encryperText=0;        
58             encryperText=(k1*plainText+k2)%26;                        
59             String result ="密匙:<"+k1+","+k2+">  "+"   密文:"+encryperText;         
60             return result;
61         }
62      
63      
64      
65 //解密算法
66     private static String jieMi(int encrypherText, int k1, int k2) {
67         // TODO Auto-generated method stub
68         int PlainText=0;
69         String result="";
70         
71          // k3(m-t)%26=c
72         PlainText=(ni(k1,26)*(encrypherText-k2))%26;              
73          result ="密匙:<"+k1+","+k2+">  "+"   明文:"+PlainText;         
74         return result;
75         
76     }
77   }
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