DES算法实现
概述(团队项目)
- DES是一个分组加密算法，它以64位为分组对数据加密。同时DES也是一个对称算法：加密和解密用的是同一个算法。DES是一个包含16个阶段的“替换–置换”的分组加密算法，64位的分组明文序列作为加密算法的输入，经过16轮加密得到64位的密文序列。
算法原理
- DES算法主要分为3部分：加解密运算、f函数的处理、轮子密钥的生成。
轮子密钥的生成
- 16个子密钥的生成主要是利用了数据表1中的数表，首先将64位的初始密钥利用PC1压缩置换位56位的密钥，然后将其一分为二，这里记为C0和D0。这里28位的C0和28位的D0分别根据LET数组相应位置的值进行左移位得到C1和D1。这是将C1和D1合并根据PC2进行压缩置换得到48位的子密钥，而且注意C1和D1作为下轮的输入以用来产生下一个子密钥。
数据表1
//PC-1
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};
//PC-2
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};
//Schedule of Left Shifts
private int[] LFT={1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1};
f函数的运算
- 从原理图中可以看到，f函数的输入是明文分组的右半分组记为R和子密钥记为K。32位的R首先要利用数据表2中的E进行E盒扩展变换得到48位的数据，这里记为RE。然后将RE与K进行异或运算并将异或结果利用数据表2中的S_BOX进行S盒替换，得到48位的运算结果记为RS。再将RS利用数据表2中的P进行P盒替换，得到32位的最终结果，记为RF。到这里f函数的运算任务就完成了。
数据表2
//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 = {//S-盒
{// S_Box[1]
{ 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 } },
{ // S_Box[2]
{ 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 } },
{ // S_Box[3]
{ 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 } },
{ // S_Box[4]
{ 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 } },
{ // S_Box[5]
{ 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 } },
{ // S_Box[6]
{ 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 } },
{ // S_Box[7]
{ 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 } },
{ // S_Box[8]
{ 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 } }
};
加解密运算
- 在第一轮中将64位的明文分为L0和R0,则加密运算如下：
L1=R0R1=L0⊕f(R0,K0),然后按此公式进行16轮的运算。
//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};
代码实现
package DES算法;
public class DES {
byte[] bytekey;
public DES(String strKey) {
this.bytekey = strKey.getBytes();
}// 声明常量字节数组
private static final 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 }; // 64
private static final 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 }; // 64
private static final int[] PC_1 = { 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 }; // 56
private static final int[] PC_2 = { 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 }; // 48
private static final 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 }; // 48
private static final 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 }; // 32
private static final int[][][] S_Box = {//S-盒
{// S_Box[1]
{ 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 } },
{ // S_Box[2]
{ 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 } },
{ // S_Box[3]
{ 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 } },
{ // S_Box[4]
{ 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 } },
{ // S_Box[5]
{ 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 } },
{ // S_Box[6]
{ 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 } },
{ // S_Box[7]
{ 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 } },
{ // S_Box[8]
{ 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 int[] LeftMove = { 1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2,2, 2, 2, 1 };
// 左移位置列表
private byte[] UnitDes(byte[] des_key, byte[] des_data, int flag) {
// 检测输入参数格式是否正确，错误直接返回空值（null）
if ((des_key.length != 8) || (des_data.length != 8)|| ((flag != 1) && (flag != 0))) {
throw new RuntimeException("Data Format Error !");
}
int flags = flag;// 二进制加密密钥
int[] keydata = new int[64];// 二进制加密数据
int[] encryptdata = new int[64]; // 加密操作完成后的字节数组
byte[] EncryptCode = new byte[8];// 密钥初试化成二维数组
int[][] KeyArray = new int[16][48];// 将密钥字节数组转换成二进制字节数组
keydata = ReadDataToBirnaryIntArray(des_key);// 将加密数据字节数组转换成二进制字节数组
encryptdata = ReadDataToBirnaryIntArray(des_data);// 初试化密钥为二维密钥数组
KeyInitialize(keydata, KeyArray); // 执行加密解密操作
EncryptCode = Encrypt(encryptdata, flags, KeyArray);
return EncryptCode;
}// 初试化密钥数组
private void KeyInitialize(int[] key, int[][] keyarray) {
int i;
int j;
int[] K0 = new int[56];// 特别注意：xxx[IP[i]-1]等类似变换
for (i = 0; i < 56; i++) {
K0[i] = key[PC_1[i] - 1]; // 密钥进行PC-1变换
}
for (i = 0; i < 16; i++) {
LeftBitMove(K0, LeftMove[i]); // 特别注意：xxx[IP[i]-1]等类似变换
for (j = 0; j < 48; j++) {
keyarray[i][j] = K0[PC_2[j] - 1]; // 生成子密钥keyarray[i][j]
}
}
} // 执行加密解密操作
private byte[] Encrypt(int[] timeData, int flag, int[][] keyarray) {
int i;
byte[] encrypt = new byte[8];
int flags = flag;
int[] M = new int[64];
int[] MIP_1 = new int[64];
// 特别注意：xxx[IP[i]-1]等类似变换
for (i = 0; i < 64; i++) {
M[i] = timeData[IP[i] - 1]; // 明文IP变换
}
if (flags == 1) { // 加密
for (i = 0; i < 16; i++) {
LoopF(M, i, flags, keyarray);
}
} else if (flags == 0) { // 解密
for (i = 15; i > -1; i--) {
LoopF(M, i, flags, keyarray);
}
}
for (i = 0; i < 64; i++) {
MIP_1[i] = M[IP_1[i] - 1]; // 进行IP-1运算
}
GetEncryptResultOfByteArray(MIP_1, encrypt);// 返回加密数据
return encrypt;
}
private int[] ReadDataToBirnaryIntArray(byte[] intdata) {
int i;
int j;
// 将数据转换为二进制数，存储到数组
int[] IntDa = new int[8];
for (i = 0; i < 8; i++) {
IntDa[i] = intdata[i];
if (IntDa[i] < 0) {
IntDa[i] += 256;
IntDa[i] %= 256;
}
}
int[] IntVa = new int[64];
for (i = 0; i < 8; i++) {
for (j = 0; j < 8; j++) {
IntVa[((i * 8) + 7) - j] = IntDa[i] % 2;
IntDa[i] = IntDa[i] / 2;
}
}
return IntVa;
}
private void LeftBitMove(int[] k, int offset) {
int i;
// 循环移位操作函数
int[] c0 = new int[28];
int[] d0 = new int[28];
int[] c1 = new int[28];
int[] d1 = new int[28];
for (i = 0; i < 28; i++) {
c0[i] = k[i];
d0[i] = k[i + 28];
}
if (offset == 1) {
for (i = 0; i < 27; i++) { // 循环左移一位
c1[i] = c0[i + 1];
d1[i] = d0[i + 1];
}
c1[27] = c0[0];
d1[27] = d0[0];
} else if (offset == 2) {
for (i = 0; i < 26; i++) { // 循环左移两位
c1[i] = c0[i + 2];
d1[i] = d0[i + 2];
}
c1[26] = c0[0];
d1[26] = d0[0];
c1[27] = c0[1];
d1[27] = d0[1];
}
for (i = 0; i < 28; i++) {
k[i] = c1[i];
k[i + 28] = d1[i];
}
}
private void LoopF(int[] M, int times, int flag, int[][] keyarray) {
int i;
int j;
int[] L0 = new int[32];
int[] R0 = new int[32];
int[] L1 = new int[32];
int[] R1 = new int[32];
int[] RE = new int[48];
int[][] S = new int[8][6];
int[] sBoxData = new int[8];
int[] sValue = new int[32];
int[] RP = new int[32];
for (i = 0; i < 32; i++) {
L0[i] = M[i]; // 明文左侧的初始化
R0[i] = M[i + 32]; // 明文右侧的初始化
}
for (i = 0; i < 48; i++) {
RE[i] = R0[E[i] - 1]; // 经过E变换扩充，由32位变为48位
RE[i] = RE[i] + keyarray[times][i]; // 与KeyArray[times][i]按位作不进位加法运算
if (RE[i] == 2) {
RE[i] = 0;
}
}
for (i = 0; i < 8; i++) { // 48位分成8组
for (j = 0; j < 6; j++) {
S[i][j] = RE[(i * 6) + j];
}
// 下面经过S盒，得到8个数
sBoxData[i] = S_Box[i][(S[i][0] << 1) + S[i][5]][(S[i][1] << 3)
+ (S[i][2] << 2) + (S[i][3] << 1) + S[i][4]];
// 8个数变换输出二进制
for (j = 0; j < 4; j++) {
sValue[((i * 4) + 3) - j] = sBoxData[i] % 2;
sBoxData[i] = sBoxData[i] / 2;
}
}
for (i = 0; i < 32; i++) {
RP[i] = sValue[P[i] - 1]; // 经过P变换
L1[i] = R0[i]; // 右边移到左边
R1[i] = L0[i] + RP[i];
if (R1[i] == 2) {
R1[i] = 0;
}
// 重新合成M，返回数组M
// 最后一次变换时，左右不进行互换。此处采用两次变换实现不变
if (((flag == 0) && (times == 0)) || ((flag == 1) && (times == 15))) {
M[i] = R1[i];
M[i + 32] = L1[i];
}
else {
M[i] = L1[i];
M[i + 32] = R1[i];
}
}
}
private void GetEncryptResultOfByteArray(int[] data, byte[] value) {
int i;
int j; // 将存储64位二进制数据的数组中的数据转换为八个整数（byte）
for (i = 0; i < 8; i++) {
for (j = 0; j < 8; j++) {
value[i] += (data[(i << 3) + j] << (7 - j));
}
}
for (i = 0; i < 8; i++) {
value[i] %= 256;
if (value[i] > 128) {
value[i] -= 255;
}
}
}
private byte[] ByteDataFormat(byte[] data, int flag) {
int len = data.length;
int padlen = 8 - (len % 8);
int newlen = len + padlen;
byte[] newdata = new byte[newlen];
System.arraycopy(data, 0, newdata, 0, len);
for (int i = len; i < newlen; i++)
newdata[i] = (byte) padlen;
return newdata;
}
public byte[] DesEncrypt(byte[] des_data, int flag) {
byte[] format_key = ByteDataFormat(bytekey, flag);
byte[] format_data = ByteDataFormat(des_data, flag);
int datalen = format_data.length;
int unitcount = datalen / 8;
byte[] result_data = new byte[datalen];
for (int i = 0; i < unitcount; i++) {
byte[] tmpkey = new byte[8];
byte[] tmpdata = new byte[8];
System.arraycopy(format_key, 0, tmpkey, 0, 8);
System.arraycopy(format_data, i * 8, tmpdata, 0, 8);
byte[] tmpresult = UnitDes(tmpkey, tmpdata, flag);
System.arraycopy(tmpresult, 0, result_data, i * 8, 8);
} // 当前为解密过程，去掉加密时产生的填充位
byte[] decryptbytearray = null;
if (flag == 0) {
int total_len = datalen;
int delete_len = result_data[total_len - 8 - 1];
delete_len = ((delete_len >= 1) && (delete_len <= 8)) ? delete_len : 0;
decryptbytearray = new byte[total_len - delete_len - 8];
boolean del_flag = true;
for (int k = 0; k < delete_len; k++) {
if (delete_len != result_data[total_len - 8 - (k + 1)])
del_flag = false;
}
if (del_flag == true) {
System.arraycopy(result_data, 0, decryptbytearray, 0, total_len- delete_len - 8);
}
}
return (flag == 1) ? result_data : decryptbytearray;
}
public static void main(String[] args) {
String key = "这是密钥";
String data = "wpy是沙雕";
DES desUtil = new DES(key);
System.err.println("加密前明文：" + data);
// 加密后的byte型的密文
byte[] result = desUtil.DesEncrypt(data.getBytes(), 1);
System.err.println("加密后密文：" + new String(result));
// 下句直接把byte类型的密文解密
System.err.println("解密后明文："+ new String(desUtil.DesEncrypt(result, 0)));
}
}
代码更改
更改要求
- 1.在项目初步设计时，我们需要将加解密的明密文进行，文件操作，即将明密文文件读入在加解密后保存至指定文件夹
- 2.同时需要进行功能选择，进行加密或解密其中一项
更改主函数代码实现
public static void main(String[] args) {
Scanner inn = new Scanner(System.in);
System.out.println("请选择你想要执行的任务：\n1.加密明文;\n2.解密密文");
int choose = inn.nextInt();
if(choose == 1){
System.out.println("请输入保存明文的文件名：");
String MFile = inn.next();
System.out.println("请输入加解密所需密钥：");
String key = inn.next();
String data = "";
int n=-1;
byte [] a=new byte[100];
try{ File f=new File(MFile);
InputStream in = new FileInputStream(f);
while((n=in.read(a,0,100))!=-1) {
data=new String (a,0,n);
}
in.close();
}
catch(IOException e) {
System.out.println("File read Error"+e);
}
DES desUtil = new DES(key);
System.err.println("加密前明文：" + data);
// 加密后的byte型的密文
byte[] result = desUtil.DesEncrypt(data.getBytes(), 1);
System.err.println("加密后密文：" + new String(result));
System.out.println("请输入保存密文的文件名：");
String MMFile = inn.next();
// 下句直接把byte类型的密文解密
File file = new File(MMFile);
try{
OutputStream out=new FileOutputStream(file);
out.write(result);
out.close();
out=new FileOutputStream(file,true);
}
catch(IOException e) {
System.out.println("Error "+e);
}
}
else if(choose == 2){
System.out.println("请输入保存密文的文件名：");
String MFile = inn.next();
System.out.println("请输入加解密所需密钥：");
String key = inn.next();
String result = "";
int n=-1;
byte [] a=new byte[100];
try{ File f=new File(MFile);
InputStream in = new FileInputStream(f);
while((n=in.read(a,0,100))!=-1) {
result=new String (a,0,n);
}
in.close();
}
catch(IOException e) {
System.out.println("File read Error"+e);
}
DES desUtil = new DES(key);
System.err.println("解密前密文：" + result);
byte [] data = desUtil.DesEncrypt(result.getBytes(), 0);
System.err.println("解密后明文："+ desUtil.DesEncrypt(result.getBytes(), 0));
System.out.println("请输入保存明文的文件名：");
String MMFile = inn.next();
File file = new File(MMFile);
try{
OutputStream out=new FileOutputStream(file);
out.write(data);
out.close();
out=new FileOutputStream(file,true);
}
catch(IOException e) {
System.out.println("Error "+e);
}
}
}
预览截图
-
施行加密
-
施行解密
遇到还未解决的问题
- DES在更改后解密时由于密文字符读入的问题发生偏差，导致解密后的明文Byte数组出现偏差，目前正在找方法解决。
