我有一个程序运行了整整16轮DES加密，但是我只需要运行1整轮即可。我的问题是我似乎无法弄清楚在哪里削减我的编码以使其停止运行完整的16个回合。谢谢您的帮助！
import javax.crypto.*;
import java.security.*;
import java.util.Scanner;
import java.util.*;
/**
* Performs encryption
*/
public class DESEncryption{
// Initial Permutation table
private static final byte[] InitialPermutation = {
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
};
// Permuted Choice 1 table
private static final byte[] PermutedChoice1 = {
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
};
private static final byte[] PermutedChoice2 = {
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
};
// Array to store the number of rotations that are to be done on each round
private static final byte[] rotations = {
1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1
};
private static final byte[] Expansion = {
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
};
private static final byte[][] SubstitutionBoxes = { {
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,
15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13
}, {
15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10,
3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5,
0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15,
13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9
}, {
10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8,
13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1,
13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7,
1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12
}, {
7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15,
13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9,
10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4,
3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14
}, {
2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9,
14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6,
4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14,
11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3
}, {
12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11,
10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8,
9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6,
4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13
}, {
4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1,
13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6,
1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2,
6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12
}, {
13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7,
1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2,
7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8,
2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11
} };
private static final byte[] Permutation = {
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
};
// Final permutation table
private static final byte[] FinalPermutation = {
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
};
private static int[] C = new int[28];
private static int[] D = new int[28];
private static int[][] subkey = new int[16][48];
public static void main(String args[]) {
System.out.println("Enter the plaintext in hexadecimal: ");
String input = new Scanner(System.in).nextLine();
int inputBits[] = new int[64];
for(int i=0 ; i < 16 ; i++) {
String s = Integer.toBinaryString(Integer.parseInt(input.charAt(i) + "", 16));
while(s.length() < 4) {
s = "0" + s;
}
for(int j=0 ; j < 4 ; j++) {
inputBits[(4*i)+j] = Integer.parseInt(s.charAt(j) + "");
}
}
System.out.println("Enter the key in hexadecimal: ");
String key = new Scanner(System.in).nextLine();
int keyBits[] = new int[64];
for(int i=0 ; i < 16 ; i++) {
String s = Integer.toBinaryString(Integer.parseInt(key.charAt(i) + "", 16));
while(s.length() < 4) {
s = "0" + s;
}
for(int j=0 ; j < 4 ; j++) {
keyBits[(4*i)+j] = Integer.parseInt(s.charAt(j) + "");
}
}
System.out.println("Encryption Rounds: ");
int outputBits[] = permute(inputBits, keyBits, false);
System.out.println("Decryption: ");
permute(outputBits, keyBits, true);
}
private static int[] permute(int[] inputBits, int[] keyBits, boolean isDecrypt) {
int newBits[] = new int[inputBits.length];
for(int i=0 ; i < inputBits.length ; i++) {
newBits[i] = inputBits[InitialPermutation[i]-1];
}
int L[] = new int[32];
int R[] = new int[32];
int i;
for(i=0 ; i < 28 ; i++) {
C[i] = keyBits[PermutedChoice1[i]-1];
}
for( ; i < 56 ; i++) {
D[i-28] = keyBits[PermutedChoice1[i]-1];
}
for(int n=0 ; n < 16 ; n++) {
System.out.println("\n-------------");
System.out.println("Round " + (n+1) + ":");
int newR[] = new int[0];
if(isDecrypt) {
newR = fiestel(R, subkey[15-n]);
BitsDisplayed(subkey[15-n]);
} else {
newR = fiestel(R, KS(n, keyBits));
BitsDisplayed(subkey[n]);
}
int newL[] = xor(L, newR);
L = R;
R = newL;
System.out.print("L = ");
BitsDisplayed(L);
System.out.print("R = ");
BitsDisplayed(R);
}
int output[] = new int[64];
System.arraycopy(R, 0, output, 0, 32);
System.arraycopy(L, 0, output, 32, 32);
int finalOutput[] = new int[64];
for(i=0 ; i < 64 ; i++) {
finalOutput[i] = output[FinalPermutation[i]-1];
}
String hex = new String();
for(i=0 ; i < 16 ; i++) {
String bin = new String();
for(int j=0 ; j < 4 ; j++) {
bin += finalOutput[(4*i)+j];
}
int decimal = Integer.parseInt(bin, 2);
hex += Integer.toHexString(decimal);
}
if(isDecrypt) {
System.out.print("Decrypted text: ");
} else {
System.out.print("Encrypted text: ");
}
System.out.println(hex.toUpperCase());
return finalOutput;
}
private static int[] KS(int round, int[] key) {
int C1[] = new int[28];
int D1[] = new int[28];
int rotationTimes = (int) rotations[round];
C1 = leftShift(C, rotationTimes);
D1 = leftShift(D, rotationTimes);
int CnDn[] = new int[56];
System.arraycopy(C1, 0, CnDn, 0, 28);
System.arraycopy(D1, 0, CnDn, 28, 28);
int Kn[] = new int[48];
for(int i=0 ; i < Kn.length ; i++) {
Kn[i] = CnDn[PermutedChoice2[i]-1];
}
subkey[round] = Kn;
C = C1;
D = D1;
return Kn;
}
private static int[] fiestel(int[] R, int[] roundKey) {
int expandedR[] = new int[48];
for(int i=0 ; i < 48 ; i++) {
expandedR[i] = R[Expansion[i]-1];
}
int temp[] = xor(expandedR, roundKey);
int output[] = sBlock(temp);
return output;
}
private static int[] xor(int[] a, int[] b) {
int answer[] = new int[a.length];
for(int i=0 ; i < a.length ; i++) {
answer[i] = a[i]^b[i];
}
return answer;
}
private static int[] sBlock(int[] bits) {
// S-boxes applied in method.
int output[] = new int[32];
for(int i=0 ; i < 8 ; i++) {
int row[] = new int [2];
row[0] = bits[6*i];
row[1] = bits[(6*i)+5];
String sRow = row[0] + "" + row[1];
int column[] = new int[4];
column[0] = bits[(6*i)+1];
column[1] = bits[(6*i)+2];
column[2] = bits[(6*i)+3];
column[3] = bits[(6*i)+4];
String sColumn = column[0] +""+ column[1] +""+ column[2] +""+ column[3];
// Converting binary to decimal value
int iRow = Integer.parseInt(sRow, 2);
int iColumn = Integer.parseInt(sColumn, 2);
int x = SubstitutionBoxes[i][(iRow*16) + iColumn];
String s = Integer.toBinaryString(x);
while(s.length() < 4) {
s = "0" + s;
}
for(int j=0 ; j < 4 ; j++) {
output[(i*4) + j] = Integer.parseInt(s.charAt(j) + "");
}
}
int finalOutput[] = new int[32];
for(int i=0 ; i < 32 ; i++) {
finalOutput[i] = output[Permutation[i]-1];
}
return finalOutput;
}
private static int[] leftShift(int[] bits, int n) {
int answer[] = new int[bits.length];
System.arraycopy(bits, 0, answer, 0, bits.length);
for(int i=0 ; i < n ; i++) {
int temp = answer[0];
for(int j=0 ; j < bits.length-1 ; j++) {
answer[j] = answer[j+1];
}
answer[bits.length-1] = temp;
}
return answer;
}
private static void BitsDisplayed (int[] bits) {
for(int i=0 ; i < bits.length ; i+=4) {
String output = new String();
for(int j=0 ; j < 4 ; j++) {
output += bits[i+j];
}
System.out.print(Integer.toHexString(Integer.parseInt(output, 2)));
}
System.out.println();
}
}
for包含以下内容的循环：
System.out.println("Round " + (n+1) + ":");
将是主要的嫌疑犯，不是吗？当然，您可能也不再需要完整的密钥扩展了。最好检查是否有未使用的字节。最好用一个常量替换for循环中的16。
请注意，该代码在permute函数内包含二进制到十六进制的转换和I / O * 。我希望密码的核心中至少有一些日志记录功能。
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