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<P>
<P>
<P>对加密解密一直挺喜欢的,可还是没有怎么好好学习过,希望这是一个好的开始。</P>
<P>在网上搜了一下关于DES的说明,发现有些杂乱,所以还是有必要整合一下。</P>
<P>写了一点代码,还没有完成,不过,还不能编译通过,^_^</P>
<P>刚看了一下,发现还是说得够模糊的,有机会再整理一下。</P>
<P>昏倒,一直运行不对,今天才仔细查出来,原来问题是出在Des_Data_P(const _b32& input, _b32 output),
</P>
<P>我的output用了传值调用,失败呀。应该是Des_Data_P(const _b32& input, _b32&
output)</P><BR>
<P>DES算法的入口参数有三个:<BR> Key, Data, Mode</P>
<P>Key 为64bit密钥, Data为64bit数据,Mode为加密还是解密。</P>
<P>DES算法的过程:</P>
<P>1. 对输入的密钥进行变换。<BR> 用户的64bit密钥,其中第8, 16, 24, 32, 40, 48, 56,
64位是校验位, 使得每个密钥都有奇数个1。所以密钥事实上是56位。对这56位密钥进行如下表的换位。</P>
<P>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, <BR>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,</P>
<P>表的意思是第57位移到第1位,第49位移到第2位,...... 以此类推。变换后得到56bit数据,将它分成两部分,C[0][28],
D[0][28]。</P>
<P>2. 计算16个子密钥,计算方法C[i][28] D[i][28]为对前一个C[i-1][28],
D[i-1][28]做循环左移操作。16次的左移位数如下表:</P>
<P> 1, 2, 3, 4, 5, 6, 7, 8,
9, 10, 11, 12, 13, 14, 15, 16 (第i次)<BR> 1, 1,
2, 2, 2, 2, 2, 2, 1, 2,
2, 2, 2, 2, 2,
1 (左移位数)</P>
<P>3. 串联计算出来的C[i][28] D[i][28] 得到56位,然后对它进行如下变换得到48位子密钥K[i][48]</P>
<P>14, 17, 11, 24, 1, 5, 3, 28,
15, 6, 21, 10, 23, 19, 12, 4, 26, 8,
16, 7, 27, 20, 13, 2,<BR>41, 52, 31, 37, 47, 55, 30, 40,
51, 45, 33, 48, 44, 49, 39, 56, 34, 53, 46, 42, 50, 36, 29, 32, </P>
<P>表的意思是第14位移到第1位,第17位移到第2位,以此类推。在此过程中,发现第9,18,22,25, 35,38,43,54位丢弃。<BR></P>
<P>4. 对64bit的明文输入进行换位变换。换位表如下:</P>
<P>58, 50, 12, 34, 26, 18, 10, 2, 60, 52, 44, 36, 28, 20, 12,
4,<BR>62, 54, 46, 38, 30, 22, 14, 6, 64, 56, 48, 40, 32, 24, 16,
8,<BR>57, 49, 41, 33, 25, 17, 9, 1, 59, 51, 43, 35, 27, 19,
11, 3,<BR>61, 53, 45, 37, 29, 21, 13, 5, 63, 55, 47, 39, 31, 23,
15, 7</P>
<P>表的意思就是第一次变换时,第58位移到第1位,第50位移到第2位,...... 依此类推。得到64位数据,将这数据前后分成两块L[0][32],
R[0][32]。</P>
<P>5. 加密过程,对R[i][32]进行扩展变换成48位数,方法如下, 记为E(R[i][32])</P>
<P>32, 1, 2, 3, 4, 5,
<BR> 4, 5, 6, 7, 8,
9,<BR> 8, 9, 10, 11, 12, 13, <BR>12, 13, 14, 15, 16,
17,<BR>16, 17, 18, 19, 20, 21,<BR>20, 21, 22, 23, 24, 25, <BR>24, 25, 26, 27,
28, 29,<BR>28, 29, 30, 31, 32, 1,</P>
<P>6. 将E(R[i][32])与K[i][48]作异或运算,得到48位数,将48位数顺序分成8份,6位一份,B[8][6]。</P>
<P>7. 使用S[i]替换B[i][6]。过程如下: 取出B[i][6]的第1位和第6位连成一个2位数m,
m就是S[i]中对应的行数(0-3),取出B[i][6]的第2到第5位连成一个4位数n(0-15),n就是S[i]中对应的列数,用S[i][m][n]代替B[i][6]。S是4行16列的对应表,里面是4位的数,一共有8个S,定义如下:</P>
<P>S[1]:<BR> 14,4,13,1,2,15,11,8,3,10,6,12,5,9,0,7,
<BR> 0,15,7,4,14,2,13,1,10,6,12,11,9,5,3,8,
<BR> 4,1,14,8,13,6,2,11,15,12,9,7,3,10,5,0,
<BR> 15,12,8,2,4,9,1,7,5,11,3,14,10,0,6,13,<BR>S[2]:<BR>
15,1,8,14,6,11,3,4,9,7,2,13,12,0,5,10, <BR>
3,13,4,7,15,2,8,14,12,0,1,10,6,9,11,5, <BR>
0,14,7,11,10,4,13,1,5,8,12,6,9,3,2,15, <BR>
13,8,10,1,3,15,4,2,11,6,7,12,0,5,14,9,<BR>S[3]:<BR>
10,0,9,14,6,3,15,5,1,13,12,7,11,4,2,8, <BR>
13,7,0,9,3,4,6,10,2,8,5,14,12,11,15,1, <BR>
13,6,4,9,8,15,3,0,11,1,2,12,5,10,14,7, <BR>
1,10,13,0,6,9,8,7,4,15,14,3,11,5,2,12,<BR>S[4]:<BR>
7,13,14,3,0,6,9,10,1,2,8,5,11,12,4,15,
<BR> 13,8,11,5,6,15,0,3,4,7,2,12,1,10,14,9,
<BR> 10,6,9,0,12,11,7,13,15,1,3,14,5,2,8,4,
<BR> 3,15,0,6,10,1,13,8,9,4,5,11,12,7,2,14, <BR>S[5]:
<BR> 2,12,4,1,7,10,11,6,8,5,3,15,13,0,14,9,
<BR> 14,11,2,12,4,7,13,1,5,0,15,10,3,9,8,6,
<BR> 4,2,1,11,10,13,7,8,15,9,12,5,6,3,0,14,
<BR> 11,8,12,7,1,14,2,13,6,15,0,9,10,4,5,3, <BR>S[6]:
<BR> 12,1,10,15,9,2,6,8,0,13,3,4,14,7,5,11,
<BR> 10,15,4,2,7,12,9,5,6,1,13,14,0,11,3,8,
<BR> 9,14,15,5,2,8,12,3,7,0,4,10,1,13,11,6,
<BR> 4,3,2,12,9,5,15,10,11,14,1,7,6,0,8,13, <BR>S[7]:
<BR> 4,11,2,14,15,0,8,13,3,12,9,7,5,10,6,1,
<BR> 13,0,11,7,4,9,1,10,14,3,5,12,2,15,8,6,
<BR> 1,4,11,13,12,3,7,14,10,15,6,8,0,5,9,2,
<BR> 6,11,13,8,1,4,10,7,9,5,0,15,14,2,3,12, <BR>S[8]:
<BR> 13,2,8,4,6,15,11,1,10,9,3,14,5,0,12,7,
<BR> 1,15,13,8,10,3,7,4,12,5,6,11,0,14,9,2,
<BR> 7,11,4,1,9,12,14,2,0,6,10,13,15,3,5,8,
<BR> 2,1,14,7,4,10,8,13,15,12,9,0,3,5,6,11,</P>
<P>8. 将从B[i][6]经过S得到的8个4位数连起来得到32位数。对这个数进行如下变换:</P>
<P> 16,7,20,21,29,12,28,17, 1,15,23,26, 5,18,31,10,
<BR> 2,8,24,14,32,27, 3, 9,19,13,30, 6,22,11, 4,25,</P>
<P> 得到的结果与L[i][32]作异或运算,把结果赋给R[i][32]。</P>
<P>9. 把R[i-1][32]的值赋给L[i],从5开始循环。直到K[16][48]结束。</P>
<P>10. 将最后的L,R合并成64位,然后进行如下转化得到最后的结果。这是对第4步的一个逆变化。<BR> 40, 8, 48, 16, 56,
24, 64, 32, <BR> 39, 7, 47, 15, 55, 23, 63, 31, <BR> 38, 6, 46, 14,
54, 22, 62, 30, <BR> 37, 5, 45, 13, 53, 21, 61, 29, <BR> 36, 4, 44,
12, 52, 20, 60, 28,<BR> 35, 3, 43, 11, 51, 19, 59, 27, <BR> 34, 2, 42,
10, 50, 18, 58, 26, <BR> 3