实验一、认识EasycodeBoyPlus

实验二、 辗转相除法

求两个数的最大公约数的算法

主要思想：用两个数中的小的去除大的，将大的扔掉，然后再用两个数（余数与较小的数）中的小的去除大的、、、、，直到余数为零。

例：求（1397，2413）
2413=13971+1016；
1397=10161+381；
1016=3812+254；
381=2541+127；
254=1272+0
import java.util.Scanner**;public class GreatestCommonFactor {
第一种方法
public static int gcd(int a,int b){
// int max1 = Math.max(a, b);
// int min1 = Math.min(a, b);
//
// while(min1>=0){
//
// int temp=max1%min1;
// System.out.println(max1+”=”+min1+”“+(max1/min1)+”+”+temp);
// max1=min1;
// min1=temp;
// if(temp==0){
// break;
// }
// //System.out.println(max1+”=”+min1+”“+(max1/min1)+”+”+temp);
// }
// return max1;
// }
第二种方法
// public static int gcd(int a,int b){
// int max1 = Math.max(a, b);
// int min1 = Math.min(a, b);
//
// while(min1>=0){
//
// int temp=max1%min1;
// System.out.println(max1+”=”+min1+”“+(max1/min1)+”+”+temp);
// max1=min1;
// min1=temp;
// if(temp==0){
// break;
// }
// //System.out.println(max1+”=”+min1+”“+(max1/min1)+”+”+temp);
// }
// return max1;
// }
第三种方法
//public static void main(String[] args) {//
// TODO 自动生成的方法存根
// Scanner sc = new Scanner(System.in);
// System.out.println(“输入第一个数，然后回车”);
// int a = sc.nextInt();// System.out.println(“输入第二个数，然后回车”);
// int b = sc.nextInt();// getResult(a,b);
//}
// public static void getResult (int a,int b){
//
//获取大的值
// int max = Math.max(a, b);
//
//获取小的值
// int min = Math.min(a, b);
// int result = max % min;
// System.out.println(max+”=”+min+”“+(max/min)+”+”+result);
// if(result == 0){
// return;
// }else{
// getResult(min,result)
// }
//
// }

}

实验三、加密算法实验之—————-异或运算实现

1. 随机产生2组二进制数，每组为32位。

1. 将这两组数进行异或运算。（按照运算规则）

要求：写成函数或者模块的形式，方便后续调用。

•异或运算

•运算符: 运算通常用符号“⊕”表示。

•运算规则:设逻辑变量A、B、C，它的运算规则为：A ⊕B = C ，读作：“A同B‘异或’等于C”。0⊕0 = 0 0⊕1 = 1

1⊕0 = 1 1⊕1 = 0

•结论：在A、B两个逻辑变量中，只要两个逻辑变量的值相同，“异或”运算的结果就为0；当两个逻辑变量的值不同时，“异或”运算的结果才为1。

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package test;
import java.util.Random;
import java.util.Scanner;
public class Test {

public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
int s=sc.nextInt();

Random r=new Random();
int a[]=new int[s];
int b[]=new int[s];


for(int i=0;i int c=(int)r.nextInt((1)+1);
a[i]=c;
System.out.print(c);


}
System.out.print(“\n”);
for(int i=0;i int d=(int)r.nextInt((1)+1);

b[i]=d;
System.out.print(d);
}
System.out.print(“\n”);
for(int i=0;i int c [] = new int [s];
c[i] = xor(a[i],b[i]);
System.out.print(c[i]);
}

}
static int xor(int a,int b){

if( a == b){
return 0;
}
return 1;
}
}
image.png

实验四、

import com.sun.management.VMOption;

import java.beans.Customizer;
import java.util.Arrays;
import java.util.Scanner;

public class DES {
//初始置换
private int[] IP = {58,50,42,34,26,18,10,2,60,52,44,36,28,20,12,4,62,54,46,38,30,22,14,6,64,56,48,40,32,24,16,8,57,49,41,33,25,17,9,1,59,51,43,35,27,19,11,3,61,53,45,37,29,21,13,5,63,55,47,39,31,23,15,7};
//逆初始置换
private int[] IP_1={40,8,48,16,56,24,64,32,39,7,47,15,55,23,63,31,38,6,46,14,54,22,62,30,37,5,45,13,53,21,61,29,36,4,44,12,52,20,60,28,35,3,43,11,51,19,59,27,34,2,42,10,50,18,58,26,33,1,41,9,49,17,57,25};
//E扩展
private int[] E={32,1,2,3,4,5,4,5,6,7,8,9,8,9,10,11,12,13,12,13,14,15,16,17,16,17,18,19,20,21,20,21,22,23,24,25,24,25,26,27,28,29,28,29,30,31,32,1};
//P置换
private int[] P={16,7,20,21,29,12,28,17,1,15,23,26,5,18,31,10,2,8,24,14,32,27,3,9,19,13,30,6,22,11,4,25};
//
private static final int[][][] S_Box={
{
{14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7 },
{0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8 },
{4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0},
{4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0}},

  1.         {
  2.                 { 15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10 },
  3.                 { 3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5 },
  4.                 { 0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15 },
  5.                 { 13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9 } },
  6.         {
  7.                 { 10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8 },
  8.                 { 13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1 },
  9.                 { 13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7 },
  10.                 { 1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12 } },
  11.         {
  12.                 { 7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15 },
  13.                 { 13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9 },
  14.                 { 10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4 },
  15.                 { 3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14 } },
  16.         {
  17.                 { 2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9 },
  18.                 { 14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6 },
  19.                 { 4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14 },
  20.                 { 11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3 } },
  21.         {
  22.                 { 12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11 },
  23.                 { 10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8 },
  24.                 { 9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6 },
  25.                 { 4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13 } },
  26.         {
  27.                 { 4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1 },
  28.                 { 13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6 },
  29.                 { 1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2 },
  30.                 { 6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12 } },
  31.         {
  32.                 { 13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7 },
  33.                 { 1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2 },
  34.                 { 7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8 },
  35.                 { 2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11 } }
  36. };
  37. //PC-1
  38. private int[] PC1={57,49,41,33,25,17,9,1,58,50,42,34,26,18,10,2,59,51,43,35,27,19,11,3,60,52,44,36,63,55,47,39,31,23,15,7,62,54,46,38,30,22,14,6,61,53,45,37,29,21,13,5,28,20,12,4};
  39. //PC-2
  40. private int[] PC2={14,17,11,24,1,5,3,28,15,6,21,10,23,19,12,4,26,8,16,7,27,20,13,2,41,52,31,37,47,55,30,40,51,45,33,48,44,49,39,56,34,53,46,42,50,36,29,32};
  41. //Schedule of left shifts
  42. private int[] LFT={1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1};
  43. //加密轮数
  44. private static final int LOOP_NUM=16;
  45. private String [] keys=new String [LOOP_NUM];
  46. private String []pContent;
  47. private String []cContent;
  48. private int origin_length;
  49. //16个子密钥
  50. private int[][] sub_key=new int[16][48];
  51. private String content;
  52. private int p_origin_length;
  53. public DES(String key,String content){
  54.     this.content=content;
  55.     p_origin_length=content.getBytes().length;
  56.     generateKeys(key);
  57. }

//拆分分组
public byte[] deal(byte[] p,int flag){
origin_length=p.length;
int g_num;
int r_num;
g_num=origin_length/8;
r_num=8-(origin_length-g_num*8);//8不填充
byte[] p_padding;
/填充/
if (r_num<8){
p_padding=new byte[origin_length+r_num];
System.arraycopy(p,0,p_padding,0,origin_length);
for(int i=0;ip_padding[origin_length+i]=(byte)r_num;
}

  1.    }else{
  2.        p_padding=p;
  3.    }
  4.    g_num=p_padding.length/8;
  5.    byte[] f_p=new byte[8];
  6.    byte[] result_data=new byte[p_padding.length];
  7.    for(int i=0;i<g_num;i++){
  8.        System.arraycopy(p_padding,i*8,f_p,0,8);
  9.        System.arraycopy(descryUnit(f_p,sub_key,flag),0,result_data,i*8,8);
  10.    }
  11.    if (flag==0){//解密
  12.        byte[] p_result_data=new byte[p_origin_length];
  13.        System.arraycopy(result_data,0,p_result_data,0,p_origin_length);
  14.        return  p_result_data;
  15.    }
  16.    return result_data;

}
/加密/
public byte[] descryUnit(byte[] p,int k[][],int flag){
int[] pbit=new int[64];
StringBuilder stringBuilder=new StringBuilder();
for(int i=0;i<8;i++){
String p_b=Integer.toBinaryString(p[i]&0xff);
while (p_b.length()%8!=0){
p_b=”0”+p_b;
}
stringBuilder.append(p_b);
}
String p_str=stringBuilder.toString();
for(int i=0;i<64;i++){
int p_t=Integer.valueOf(p_str.charAt(i));
if(p_t48){
p_t=0;
}else if(p_t49){
p_t=1;
}else{
System.out.println(“To bit error!”);
}
p_bit[i]=p_t;
}
/**_IP置换**/
int [] p_IP=new int[64];
for (int i=0;i<64;i++){
p_IP[i]=p_bit[IP[i]-1];
}
if (flag == 1) { // 加密
for (int i = 0; i < 16; i++) {
L(p_IP, i, flag, k[i]);
}
} else if (flag == 0) { // 解密
for (int i = 15; i > -1; i—) {
L(p_IP, i, flag, k[i]);
}
}
int[] c=new int[64];
for(int i=0;ic[i]=p_IP[IP_1[i]-1];
}
byte[] c_byte=new byte[8];
for(int i=0;i<8;i++){
c_byte[i]=(byte) ((c[8_i]<<7)+(c[8_i+1]<<6)+(c[8_i+2]<<5)+(c[8_i+3]<<4)+(c[8_i+4]<<3)+(c[8_i+5]<<2)+(c[8_i+6]<<1)+(c[8_i+7]));
}
return c_byte;

  1. }
  2. public void L(int[] M, int times, int flag, int[] keyarray){
  3.     int[] L0=new int[32];
  4.     int[] R0=new int[32];
  5.     int[] L1=new int[32];
  6.     int[] R1=new int[32];
  7.     int[] f=new int[32];
  8.     System.arraycopy(M,0,L0,0,32);
  9.     System.arraycopy(M,32,R0,0,32);
  10.     L1=R0;
  11.     f=fFuction(R0,keyarray);
  12.     for(int j=0;j<32;j++){
  13.         R1[j]=L0[j]^f[j];
  14.         if (((flag == 0) && (times == 0)) || ((flag == 1) && (times == 15))) {
  15.             M[j] = R1[j];
  16.             M[j + 32] = L1[j];
  17.         }
  18.         else {
  19.             M[j] = L1[j];
  20.             M[j + 32] = R1[j];
  21.         }
  22.     }
  24. }
  25. public int[] fFuction(int [] r_content,int [] key){
  26.     int[] result=new int[32];
  27.     int[] e_k=new int[48];
  28.     for(int i=0;i<E.length;i++){
  29.         e_k[i]=r_content[E[i]-1]^key[i];
  30.     }
  31.     /********S盒替换:由48位变32位，现分割e_k，然后再进行替换*********/
  32.     int[][] s=new int[8][6];
  33.     int[]s_after=new int[32];
  34.     for(int i=0;i<8;i++){
  35.         System.arraycopy(e_k,i*6,s[i],0,6);
  36.         int r=(s[i][0]<<1)+ s[i][5];//横坐标
  37.         int c=(s[i][1]<<3)+(s[i][2]<<2)+(s[i][3]<<1)+s[i][4];//纵坐标
  38.         String str=Integer.toBinaryString(S_Box[i][r][c]);
  39.         while (str.length()<4){
  40.             str="0"+str;
  41.         }
  42.         for(int j=0;j<4;j++){
  43.             int p=Integer.valueOf(str.charAt(j));
  44.             if(p==48){
  45.                 p=0;
  46.             }else if(p==49){
  47.                 p=1;
  48.             }else{
  49.                 System.out.println("To bit error!");
  50.             }
  51.             s_after[4*i+j]=p;
  52.         }
  54.     }
  55.     /******S盒替换结束*******/
  56.     /****P盒替代****/
  57.     for(int i=0;i<P.length;i++){
  58.         result[i]=s_after[P[i]-1];
  59.     }
  60.     return result;
  62. }
  63. /**生成子密钥**/
  64. public void generateKeys(String key){
  65.     while (key.length()<8){
  66.         key=key+key;
  67.     }
  68.     key=key.substring(0,8);
  69.     byte[] keys=key.getBytes();
  70.     int[] k_bit=new int[64];
  71.     //取位值
  72.     for(int i=0;i<8;i++){
  73.         String k_str=Integer.toBinaryString(keys[i]&0xff);
  74.         if(k_str.length()<8){
  75.             for(int t=0;t<8-k_str.length();t++){
  76.                 k_str="0"+k_str;
  77.             }
  78.         }
  79.         for(int j=0;j<8;j++){
  80.             int p=Integer.valueOf(k_str.charAt(j));
  81.             if(p==48){
  82.                 p=0;
  83.             }else if(p==49){
  84.                 p=1;
  85.             }else{
  86.                 System.out.println("To bit error!");
  87.             }
  88.             k_bit[i*8+j]=p;
  89.         }
  90.     }
  91.     //k_bit是初始的64位长密钥，下一步开始进行替换
  92.     /***********PC-1压缩****************/
  93.     int [] k_new_bit=new int[56];
  94.     for(int i=0;i<PC1.length;i++){
  95.         k_new_bit[i]=k_bit[PC1[i]-1];
  96.     }
  97.     /**************************/
  98.     int[] c0=new int[28];
  99.     int[] d0=new int[28];
  100.     System.arraycopy(k_new_bit,0,c0,0,28);
  101.     System.arraycopy(k_new_bit,28,d0,0,28);
  102.     for(int i=0;i<16;i++){
  103.         int[] c1=new int[28];
  104.         int[] d1=new int[28];
  105.         if(LFT[i]==1){
  106.             System.arraycopy(c0,1,c1,0,27);
  107.             c1[27]=c0[0];
  108.             System.arraycopy(d0,1,d1,0,27);
  109.             d1[27]=d0[0];
  110.         }else if(LFT[i]==2){
  111.             System.arraycopy(c0,2,c1,0,26);
  112.             c1[26]=c0[0];
  113.             c1[27]=c0[1];//这里手残之前写成c1
  115.             System.arraycopy(d0,2,d1,0,26);
  116.             d1[26]=d0[0];
  117.             d1[27]=d0[1];
  118.         }else{
  119.             System.out.println("LFT Error!");
  120.         }
  121.         int[] tmp=new int[56];
  122.         System.arraycopy(c1,0,tmp,0,28);
  123.         System.arraycopy(d1,0,tmp,28,28);
  124.         for (int j=0;j<PC2.length;j++){//PC2压缩置换
  125.             sub_key[i][j]= tmp[PC2[j]-1];
  126.         }
  127.         c0=c1;
  128.         d0=d1;
  129.     }
  131. }
  132. public static void main(String []args){
  133.     Scanner sc=new Scanner(System.in);
  134.     String origin=sc.nextLine();
  135.     System.out.println("原文："+origin);
  136.     DES customerDES=new DES("密码学专栏", origin);
  137.     byte[] c=customerDES.deal(origin.getBytes(),1);
  138.     System.out.println("密文：\n"+new String(c));
  139.     byte[] p=customerDES.deal(c,0);
  140.     byte[] p_d=new byte[origin.getBytes().length];
  141.     System.arraycopy(p,0,p_d,0,origin.getBytes().length);
  142.     System.out.println("明文：\n"+new String(p));
  146. }

}