simple-des算法的java实现

下面的代码是simple-des算法的java完整实现，可以直接运行。

import java.io.IOException;public class SimpleDES {/** * @param args */// two keys K1 and K2static int K1=0;static int K2=0;/*some parameters*/static int P10[]=new int[]{3,5,2,7,4,10,1,9,8,6};static int P8[]=new int[]{6,3,7,4,8,5,10,9};static int P4[]=new int[]{2,4,3,1};static int IP[]=new int[]{2,6,3,1,4,8,5,7};static int IPI[]=new int[]{4,1,3,5,7,2,8,6};static int EP[]=new int[]{4,1,2,3,2,3,4,1};static int S0[][]={ {1,0,3,2}, {3,2,1,0}, {0,2,1,3}, {3,1,3,2},};static int S1[][]={ {0,1,2,3}, {2,0,1,3}, {3,0,1,0}, {2,1,0,3},};//根据数组交换static int Permute(int num,int p[],int pmax){int result=0;for(int i=0;i<p.length;i++){result<<=1;result|=(num>>(pmax-p[i]))&1;}return result;}//生成k1,k2static void SDES(String Key){int K=Integer.parseInt(Key,2);K=Permute(K,P10,10);int th=0,tl=0;th=(K>>5)&0x1f;//取Key的高5位tl=K&0x1f; //取Key的低5位//LS-1 th=((th&0xf)<<1) | ((th & 0x10) >> 4);//循环左移一位 tl=((tl&0xf)<<1) | ((tl & 0x10) >> 4);//循环左移一位 K1=Permute(( th << 5)| tl,P8,10); //生成K1 System.out.println("K1:"+Integer.toString(K1,2)); //LS-2 th=((th & 0x07)<< 2) |((th & 0x18) >> 3);//循环左移二位 tl=((tl & 0x07)<< 2) |((tl & 0x18) >> 3);//循环左移二位 K2=Permute((th<<5) | tl,P8,10); //生成K2 System.out.println("K2:"+Integer.toString(K2,2));}//f函数static int F(int R,int K){int t=Permute(R,EP,4)^K; int t0=(t>>4)& 0xf; int t1=t&0xf; t0= S0[((t0 & 0x8)>>2) | (t0 & 1)] [(t0>>1)&0x3]; t1= S1[((t1 & 0x8)>>2) | (t1 & 1)] [(t1>>1)&0x3]; t= Permute((t0<<2)|t1,P4,4); return t;}//fk函数static int fk(int input,int k){int l=(input>>4) & 0xf; int r=input & 0xf; return ((l^F(r,k))<< 4)| r;}//switch functionstatic int SW(int x){ return ((x&0xf)<<4) | ((x>>4)&0xf);}//加密static String encrypt(String input){int m=Integer.parseInt(input, 2);m=Permute(m,IP,8); m=fk(m,K1); m=SW(m); m=fk(m,K2); m=Permute(m,IPI,8);return Integer.toString(m, 2);}//解密static String decrypt(String input){int m=Integer.parseInt(input, 2);m=Permute(m,IP,8); m=fk(m,K2); m=SW(m); m=fk(m,K1); m=Permute(m,IPI,8); return Integer.toString(m, 2);}public static void main(String[] args) throws IOException {// TODO Auto-generated method stubString plaintext,ciphertext,key;java.util.Scanner scan = new java.util.Scanner(System.in);System.out.println("1:加密,2:解密,3:退出,请输入一个数字来选择:"); int mode=scan.nextInt();while(true){if(mode==1){System.out.println("请输入明文:");plaintext=scan.next();System.out.println("请输入密钥:");key=scan.next();SDES(key);ciphertext=encrypt(plaintext);//如果密文不足8位，补足8位if(ciphertext.length()<8){for(int i=0;i<8-ciphertext.length();i++)ciphertext="0"+ciphertext;}System.out.println("加密后的密文为:"+ciphertext);}else if(mode==2){System.out.println("请输入密文:");ciphertext=scan.next();System.out.println("请输入密钥:");key=scan.next();SDES(key);plaintext=decrypt(ciphertext);if(plaintext.length()<8){for(int i=0;i<8-plaintext.length();i++)plaintext="0"+plaintext;}System.out.println("解密后的明文为:"+plaintext);}else if(mode==3) break;System.out.println("1:加密,2:解密,3:退出,请输入一个数字来选择:");mode=scan.nextInt();}}}