密码课程设计第一个小题目，Playfair密码算法实现。JAVA版实现。
- import java.util.*;
- public class PlayfairCoder{
- public static int checkChar(char c){
- if(c>='A'&&c<='Y')
- return 1;
- else
- return 0;
- }
- /*
- *格式化密钥材料
- */
- public static String formatKey(String key){
- StringBuffer sb=new StringBuffer();
- HashSet<Character> hs=new HashSet<Character>();
- char n;
- String k=key.toUpperCase();
- char[] detail=new char[25];
- for(int i=0,j=65;i<25;i++,j++)
- detail[i]=(char)j;
- for(int i=0;i<k.length();i++){
- n=k.charAt(i);
- if(!hs.contains(n)&&checkChar(n)==1){
- sb.append(n);
- hs.add(n);
- }
- }
- int i=0;
- while(sb.length()!=25){
- char t=detail[i];
- if(!hs.contains(t)){
- sb.append(t);
- hs.add(t);
- }
- i++;
- }
- return sb.toString();
- }
- /*
- *生成密钥矩阵
- */
- public static char[][] initKey(String k){
- char[][] key=new char[5][5];
- String s=formatKey(k);
- int m=0;
- for(int i=0;i<5;i++)
- for(int j=0;j<5;j++){
- key[i][j]=s.charAt(m);
- m++;
- }
- return key;
- }
- /*
- *格式化明文
- */
- public static String formatData(String data,String sign){
- String updata=data.toUpperCase();
- String ming="",temp="";
- char c;
- Stack<Character> stack=new Stack<Character>();
- for(int i=0;i<updata.length();i++){
- c=updata.charAt(i);
- if(checkChar(c)==1){
- if(stack.size()%2!=0){
- if(stack.peek()==c){
- stack.push(sign.charAt(0));
- stack.push(c);
- }
- else
- stack.push(c);
- }
- else
- stack.push(c);
- }
- }
- while(stack.size()>0)
- temp+=stack.pop();
- for(int i=temp.length()-1;i>-1;i--)
- ming+=temp.charAt(i);
- if(ming.length()%2!=0)
- ming+=sign.charAt(0);
- return ming;
- }
- public static String getEnData(char a,char b,char[][] k){
- String result="";
- int h=0,l=0,m=0,n=0;
- for(int i=0;i<k.length;i++)
- for(int j=0;j<k[i].length;j++){
- if(a==k[i][j]){
- h=i;
- l=j;
- }
- if(b==k[i][j]){
- m=i;
- n=j;
- }
- }
- if(h!=m&&l!=n)
- result=result+k[h][n]+k[m][l];
- else if(h==m){
- if(l==4)
- result=result+k[h][0]+k[h][n+1];
- else if(n==4)
- result=result+k[h][l+1]+k[h][0];
- else
- result=result+k[h][l+1]+k[h][n+1];
- }
- else if(l==n){
- if(h==4)
- result=result+k[0][l]+k[m+1][l];
- else if(m==4)
- result=result+k[h+1][l]+k[0][l];
- else
- result=result+k[h+1][l]+k[m+1][l];
- }
- return result;
- }
- public static String getDeData(char a,char b,char[][] k){
- String result="";
- int h=0,l=0,m=0,n=0;
- for(int i=0;i<k.length;i++)
- for(int j=0;j<k[i].length;j++){
- if(a==k[i][j]){
- h=i;
- l=j;
- }
- if(b==k[i][j]){
- m=i;
- n=j;
- }
- }
- if(h!=m&&l!=n)
- result=result+k[h][n]+k[m][l];
- else if(h==m){
- if(l==0)
- result=result+k[h][4]+k[h][n-1];
- else if(n==0)
- result=result+k[h][l-1]+k[h][4];
- else
- result=result+k[h][l-1]+k[h][n-1];
- }
- else if(l==n){
- if(h==0)
- result=result+k[4][l]+k[m-1][l];
- else if(m==0)
- result=result+k[h-1][l]+k[4][l];
- else
- result=result+k[h-1][l]+k[m-1][l];
- }
- return result;
- }
- /*
- *加密
- */
- public static String encrypt(String key,String data,String sign){
- char[][] k=initKey(key);
- String d=formatData(data,sign);
- String endata="";
- int i=0,j=1;
- char a,b;
- while(j<d.length()){
- a=d.charAt(i);
- b=d.charAt(j);
- endata=endata+getEnData(a,b,k);
- i+=2;
- j+=2;
- }
- return endata;
- }
- /*
- *解密
- */
- public static String decrypt(String key,String data,String sign){
- char[][] k=initKey(key);
- String dedata="";
- int i=0,j=1;
- char a,b;
- while(j<data.length()){
- a=data.charAt(i);
- b=data.charAt(j);
- dedata=dedata+getDeData(a,b,k);
- i+=2;
- j+=2;
- }
- dedata=dedata.replaceAll(sign,"");
- return dedata;
- }
- public static void main(String[] str){
- Scanner sc=new Scanner(System.in);
- System.out.print("请输入密钥: ");
- String arr=sc.nextLine();
- System.out.print("请输入明文: ");
- String m=sc.nextLine();
- System.out.print("请输入标志字符");
- String sign=sc.nextLine().toUpperCase();
- String t=formatData(m,sign);
- System.out.println("明文格式化: "+t+"\n密钥矩阵:");
- char[][] testarr=initKey(arr);
- for(int i=0;i<5;i++)
- for(int j=0;j<5;j++){
- System.out.print(testarr[i][j]+" ");
- if(j==4)
- System.out.println("");
- }
- String jia=encrypt(arr,m,sign);
- System.out.println("加密后: "+jia);
- System.out.println("解密后: "+decrypt(arr,jia,sign));
- }
- }