des算法的java实现！

public class DesUtil {
 byte[] bytekey;

 public DesUtil(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 = {
   { { 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[1]
   { 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[2]
   { 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[3]
   { 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[4]
   { 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[5]
   { 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[6]
   { 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[7]
   { 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 } } // S_Box[8]
 };

 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 = "12345678";
  String data = "Don't tell anybody!!";
  DesUtil desUtil = new DesUtil(key);
  System.err.println("加密之前的数据：" + data);
  // 加密后的byte型的密文
  byte[] result = desUtil.DesEncrypt(data.getBytes(), 1);
  System.err.println("加密之后的数据：" + new String(result));
  // 下句直接把byte类型的密文解密，能正确还原
  System.err.println("byte型乱码直接解密："
    + new String(desUtil.DesEncrypt(result, 0)) + "(正确)");

  // 但先将byte型密文转成String,解密时再将String型转成byte转入时，不能正确还原
  String str = new String(result);
  System.err.println("String型乱码解密："
    + new String(desUtil.DesEncrypt(str.getBytes(), 0)) + "(错误)");
 }
}
运行结果：