private static final char[] BASE64_CHARSET = BASE64_CHARS.toCharArray();
// 声明常量字节数组
/**
* DES算法把64位的明文输入块变 64位的密文输出块，它所使用的密钥也是64位, 其功能是把输入的64位数据块按位重新组合，
* 并把输出分 L0、R0两部分，每部分各长32位，其置换规则见下表 即将输入的第58位换到第一位，第50位换到第2位，...，依此类推，
* 最后一位是原来的第7位。L0、R0则是换位输出后的两部分， L0是输出的左32位，R0 是右32位，
* 例：设置换前的输入值 D1D2D3......D64， 则经过初始置换后的结果 ：L0=D550...D8；R0=D57D49...D7
*/
private static final int[] IP = { // OK
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
/**
* 经过26次迭代运算后。得到L16、R16，将此作 输入，进行逆置换，即得到密文输出。
* 逆置换正好是初始置的逆运算，例如，第1位经过初始置换后，处於第40位， 而通过逆置换，又将第40位换回到第1位，其逆置换规则如下表所示：
*/
private static final int[] IP_1 = { // OK
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
/**
* PC1置换
*/
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
/**
* PC2置换
*/
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,
/**
* 放大换位表
*/
private static final int[] E = { // OK
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
/**
* 单纯换位表
*/
private static final int[] P = { // OK
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
/**
* 在f(Ri,Ki)算法描述图中，S1,S2...S8 选择函数，其功能是把6bit数据变 4bit数据。
* 下面给出选择函数Si(i=1,2......8)的功能表：选择函数Si
*/
private static final int[][][] S_Box = {
{// S_Box[1] OK
{ 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] OK
{ 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] OK
{ 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] OK