最近这几天真的比较郁闷,却说不出为什么郁闷。很多事要做,但是都因为能力问题,时间都花得事倍功半。星期一又要来了,作业什么时候才能编好?
今天早上在弄了一个早上的DES算法,要是引用C#内部已封装好的DES还不简单?设置好密钥和向量就可以了,但是这样老师给的分数不高啊,而且自己真的想自己写一个出来。写着写着突然发现以现在自己已自学到的水平还很不够,还没有深入地去操作过某类数据,例如比特。DES的明文64比特,分左右两部分,这好办,前32位是4个byte,后32位是4个byte。但是,密钥除去8位校检码,只有56位啊,分左右两个部分那就是28位,28%8!=0哦,怎么办?于是就想到自己对C#里的位操作还是一无所知。
还好上网找了一下,看到了一线希望,是BitArray给我带来的希望。以下引用msdn的例子:
2using System.Collections;
3public class SamplesBitArray {
4
5 public static void Main() {
6
7 // Creates and initializes several BitArrays.
8 BitArray myBA1 = new BitArray( 5 );
9
10 BitArray myBA2 = new BitArray( 5, false );
11
12 byte[] myBytes = new byte[5] { 1, 2, 3, 4, 5 };
13 BitArray myBA3 = new BitArray( myBytes );
14
15 bool[] myBools = new bool[5] { true, false, true, true, false };
16 BitArray myBA4 = new BitArray( myBools );
17
18 int[] myInts = new int[5] { 6, 7, 8, 9, 10 };
19 BitArray myBA5 = new BitArray( myInts );
20
21 // Displays the properties and values of the BitArrays.
22 Console.WriteLine( "myBA1" );
23 Console.WriteLine( " Count: {0}", myBA1.Count );
24 Console.WriteLine( " Length: {0}", myBA1.Length );
25 Console.WriteLine( " Values:" );
26 PrintValues( myBA1, 8 );
27
28 Console.WriteLine( "myBA2" );
29 Console.WriteLine( " Count: {0}", myBA2.Count );
30 Console.WriteLine( " Length: {0}", myBA2.Length );
31 Console.WriteLine( " Values:" );
32 PrintValues( myBA2, 8 );
33
34 Console.WriteLine( "myBA3" );
35 Console.WriteLine( " Count: {0}", myBA3.Count );
36 Console.WriteLine( " Length: {0}", myBA3.Length );
37 Console.WriteLine( " Values:" );
38 PrintValues( myBA3, 8 );
39
40 Console.WriteLine( "myBA4" );
41 Console.WriteLine( " Count: {0}", myBA4.Count );
42 Console.WriteLine( " Length: {0}", myBA4.Length );
43 Console.WriteLine( " Values:" );
44 PrintValues( myBA4, 8 );
45
46 Console.WriteLine( "myBA5" );
47 Console.WriteLine( " Count: {0}", myBA5.Count );
48 Console.WriteLine( " Length: {0}", myBA5.Length );
49 Console.WriteLine( " Values:" );
50 PrintValues( myBA5, 8 );
51 }
52
53 public static void PrintValues( IEnumerable myList, int myWidth ) {
54 int i = myWidth;
55 foreach ( Object obj in myList ) {
56 if ( i <= 0 ) {
57 i = myWidth;
58 Console.WriteLine();
59 }
60 i--;
61 Console.Write( "{0,8}", obj );
62 }
63 Console.WriteLine();
64 }
65
66}
67
68
69/*
70This code produces the following output.
71
72myBA1
73 Count: 5
74 Length: 5
75 Values:
76 False False False False False
77myBA2
78 Count: 5
79 Length: 5
80 Values:
81 False False False False False
82myBA3
83 Count: 40
84 Length: 40
85 Values:
86 True False False False False False False False
87 False True False False False False False False
88 True True False False False False False False
89 False False True False False False False False
90 True False True False False False False False
91myBA4
92 Count: 5
93 Length: 5
94 Values:
95 True False True True False
96myBA5
97 Count: 160
98 Length: 160
99 Values:
100 False True True False False False False False
101 False False False False False False False False
102 False False False False False False False False
103 False False False False False False False False
104 True True True False False False False False
105 False False False False False False False False
106 False False False False False False False False
107 False False False False False False False False
108 False False False True False False False False
109 False False False False False False False False
110 False False False False False False False False
111 False False False False False False False False
112 True False False True False False False False
113 False False False False False False False False
114 False False False False False False False False
115 False False False False False False False False
116 False True False True False False False False
117 False False False False False False False False
118 False False False False False False False False
119 False False False False False False False False
120*/
121
BitArray myBA1 = new BitArray( 5 );
myBA1为5位,取用默认初始化,5位都为 False。即为0,由此可见,平时一位的值0和1在C#里面变成False和True;
byte[] myBytes = new byte[5] { 1, 2, 3, 4, 5 };
BitArray myBA3 = new BitArray( myBytes );
myBytes为byte数组,内容为1,2,3,4,5;二进制就是00000001,00000010,00000011,00000100,00000101,myBA3就为相应的5*8=40位;
bool[] myBools = new bool[5] { true, false, true, true, false };
BitArray myBA4 = new BitArray( myBools );
看输出,bool就想当于一位,myBools是长度为5的数组,变成myBA4后,也是5位;
int[] myInts = new int[5] { 6, 7, 8, 9, 10 };
BitArray myBA5 = new BitArray( myInts );
int是32位的,5个,换成BitArray当然就是5*32=160。
还应注意的是PrintValues方法,参数(IEnumerable myList, int myWidth ),foreach()循环,每行打印8个。有了这个我想DES做起来主要问题就不大了。做好了发上来给大家看看啊。
原文地址:http://www.cnblogs.com/lanse777/archive/2007/04/01/695801.aspx