Des

DES加密算法
import java.util.Scanner;
public class Des {
static 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};

static int ip1[] = {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};


//将数据扩展为64位bit
public static String getBit(int n){
    //构造64个"0"
    StringBuffer stringBuffer = new StringBuffer();
    for (int i = 0; i < 64; i++) {
        stringBuffer.append("0");
    }
    //将十进制参数转化为二进制
    String binary = Integer.toBinaryString(n);
    //将二进制的数长度扩展为64为
    binary = stringBuffer.substring(0, 64 - binary.length()) + binary;
    return binary;
}

//进行初始置换
public static StringBuffer IPChange(String m){
    StringBuffer dst = new StringBuffer();
    for (int i = 0; i < m.length(); i++) {
        dst.append(m.charAt(ip[i]-1));

    }
    return dst;
}

//进行初始逆置换
public static StringBuffer IP1Change(String m){
    StringBuffer dst = new StringBuffer();
    for (int i = 0; i < m.length(); i++) {
        dst.append(m.charAt(ip1[i]-1));
    }
    return dst;
}

public static void main(String[] args) {
    int m = 0;
    System.out.println("请输入一个明文：");
    Scanner input = new Scanner(System.in);
    m = input.nextInt();
    String binary = getBit(m);
    System.out.println("开始执行");
    StringBuffer IPSb = IPChange(binary);
    StringBuffer IP1Sb = IP1Change(IPSb.toString());
    System.out.println("初始置换后的值为:"+IPSb.toString());
    System.out.println("初始逆置换后的值为:"+IP1Sb.toString());
}
}
pentiumCM/Des

Des
