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[转载]如何使用Base64进行加密和解密

原创 Linux操作系统 作者：dinner1007 时间：2019-06-20 09:39:04 0 删除 编辑
如何使用Base64进行加密和解密
如何使用Base64进行加密和解密

其实Base64的加密和解密的算法不是很复杂，首先是定义自己64位的密钥，64个字符是固定，但是顺序是可以随自己的设计而变化。例如：

char[] BaseTable=new char[64]{

'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z',

'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z',

'0','1','2','3','4','5','6','7','8','9','+','/'};

接下来，在加密的时候就是对于需要加密的每个字符，通过一定的算法，转换成上面64字符的一种；而在解密的时候则是把64字符中任意一个字符反算出加密前的字符。对于每个字符的操作有很多方法，这里就不一一介绍了。需要注意的是“=”字符，在Base64加密算法中，是很重要的，它是起到补零作用。

以下是完整代码：

//----------------------------- Base64 class --------------------------------------

//---------------------------------------------------------------------------------

//---File:clsBase64

//---Description:The class file to encode string or decode string in base algorith

//---Author:Knight

//---Date:Oct.8, 2005

//---------------------------------------------------------------------------------

//----------------------------{ Base64 class }-------------------------------------

using System;

namespace Base64

{

///

/// Summary description for clsBase64.

///

public class clsBase64

{

private char[] source;

private char[] lookupTable;

private int length, length2, length3;

private int blockCount;

private int paddingCount;

public clsBase64()

{

//

// TODO: Add constructor logic here

//

source = null;

length = length2 = length3 =0;

blockCount = 0;

paddingCount = 0;

}

///

/// Create base64 char array using default base64 char array

///

///

/// return the new base64 char array

private char[] CreateBase64Char( ref char[] CreatePara )

{

char[] BaseTable=new char[64]{

'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z',

'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z',

'0','1','2','3','4','5','6','7','8','9','+','/'};

const int CREATE_TYPE = 8;

byte bParaValue = 0;

byte bTemp;

for( int i = 0; i < CreatePara.Length; i++ )

{

bTemp = ( byte )( CreatePara[i] );

switch( bTemp % CREATE_TYPE )

{

case 1:

// 00000001

bTemp =( byte )( bTemp ^ 0x01 );

break;

case 2:

// 00000010

bTemp =( byte )( bTemp ^ 0x02 );

break;

case 3:

// 00000100

bTemp =( byte )( bTemp ^ 0x04 );

break;

case 4:

// 00001000

bTemp =( byte )( bTemp ^ 0x08 );

break;

case 5:

// 00010000

bTemp =( byte )( bTemp ^ 0x10 );

break;

case 6:

// 00100000

bTemp =( byte )( bTemp ^ 0x20 );

break;

case 7:

// 01000000

bTemp =( byte )( bTemp ^ 0x40 );

break;

default:

// 10000000

bTemp =( byte )( bTemp ^ 0x80 );

break;

}

bParaValue =( byte )( bParaValue ^ bTemp );

}

char chrTemp;

int nIndex;

switch( bParaValue % CREATE_TYPE )

{

case 1:

// Exechange 0 <--> 1, 2 <--> 3, 4 <--> 5, 6 <--> 7

for( int i = 0; i < BaseTable.Length / CREATE_TYPE; i++ )

{

nIndex = i * CREATE_TYPE;

chrTemp = BaseTable[nIndex];

BaseTable[nIndex] = BaseTable[nIndex + 1];

BaseTable[nIndex + 1] = chrTemp;

chrTemp = BaseTable[nIndex + 2];

BaseTable[nIndex + 2] = BaseTable[nIndex + 3];

BaseTable[nIndex + 3] = chrTemp;

chrTemp = BaseTable[nIndex + 4];

BaseTable[nIndex + 4] = BaseTable[nIndex + 5];

BaseTable[nIndex + 5] = chrTemp;

chrTemp = BaseTable[nIndex + 6];

BaseTable[nIndex + 6] = BaseTable[nIndex + 7];

BaseTable[nIndex + 7] = chrTemp;

}

break;

case 2:

// Exechange 0 <--> 2, 1 <--> 3, 4 <--> 6, 5 <--> 7

for( int i = 0; i < BaseTable.Length / CREATE_TYPE; i++ )

{

nIndex = i * CREATE_TYPE;

chrTemp = BaseTable[nIndex];

BaseTable[nIndex] = BaseTable[nIndex + 2];

BaseTable[nIndex + 2] = chrTemp;

chrTemp = BaseTable[nIndex + 1];

BaseTable[nIndex + 1] = BaseTable[nIndex + 3];

BaseTable[nIndex + 3] = chrTemp;

chrTemp = BaseTable[nIndex + 4];

BaseTable[nIndex + 4] = BaseTable[nIndex + 6];

BaseTable[nIndex + 6] = chrTemp;

chrTemp = BaseTable[nIndex + 5];

BaseTable[nIndex + 5] = BaseTable[nIndex + 7];

BaseTable[nIndex + 7] = chrTemp;

}

break;

case 3:

// Exechange 0 <--> 3, 1 <--> 2, 4 <--> 7, 5 <--> 6

for( int i = 0; i < BaseTable.Length / CREATE_TYPE; i++ )

{

nIndex = i * CREATE_TYPE;

chrTemp = BaseTable[nIndex];

BaseTable[nIndex] = BaseTable[nIndex + 3];

BaseTable[nIndex + 3] = chrTemp;

chrTemp = BaseTable[nIndex + 1];

BaseTable[nIndex + 1] = BaseTable[nIndex + 2];

BaseTable[nIndex + 2] = chrTemp;

chrTemp = BaseTable[nIndex + 4];

BaseTable[nIndex + 4] = BaseTable[nIndex + 7];

BaseTable[nIndex + 7] = chrTemp;

chrTemp = BaseTable[nIndex + 5];

BaseTable[nIndex + 5] = BaseTable[nIndex + 6];

BaseTable[nIndex + 6] = chrTemp;

}

break;

case 4:

// Mirror exechange

for( int i = 0; i < BaseTable.Length / CREATE_TYPE; i++ )

{

nIndex = i * CREATE_TYPE;

chrTemp = BaseTable[nIndex];

BaseTable[nIndex] = BaseTable[nIndex + CREATE_TYPE - 1];

BaseTable[nIndex + CREATE_TYPE - 1] = chrTemp;

chrTemp = BaseTable[nIndex + 1];

BaseTable[nIndex + 1] = BaseTable[nIndex + CREATE_TYPE - 2];

BaseTable[nIndex + CREATE_TYPE - 2] = chrTemp;

chrTemp = BaseTable[nIndex + 2];

BaseTable[nIndex + 2] = BaseTable[nIndex + CREATE_TYPE - 3];

BaseTable[nIndex + CREATE_TYPE - 3] = chrTemp;

chrTemp = BaseTable[nIndex + 3];

BaseTable[nIndex + 3] = BaseTable[nIndex + CREATE_TYPE - 4];

BaseTable[nIndex + CREATE_TYPE - 4] = chrTemp;

}

break;

case 5:

// Exechange 0 <--> 4, 1 <--> 5, 2 <--> 6, 3 <--> 7

for( int i = 0; i < BaseTable.Length / CREATE_TYPE; i++ )

{

nIndex = i * CREATE_TYPE;

chrTemp = BaseTable[nIndex];

BaseTable[nIndex] = BaseTable[nIndex + 4];

BaseTable[nIndex + 4] = chrTemp;

chrTemp = BaseTable[nIndex + 1];

BaseTable[nIndex + 1] = BaseTable[nIndex + 5];

BaseTable[nIndex + 5] = chrTemp;

chrTemp = BaseTable[nIndex + 2];

BaseTable[nIndex + 2] = BaseTable[nIndex + 6];

BaseTable[nIndex + 6] = chrTemp;

chrTemp = BaseTable[nIndex + 3];

BaseTable[nIndex + 3] = BaseTable[nIndex + 7];

BaseTable[nIndex + 7] = chrTemp;

}

break;

case 6:

// Exechange 0 <--> 5, 1 <--> 6, 2 <--> 7, 3 <--> 4

for( int i = 0; i < BaseTable.Length / CREATE_TYPE; i++ )

{

nIndex = i * CREATE_TYPE;

chrTemp = BaseTable[nIndex];

BaseTable[nIndex] = BaseTable[nIndex + 5];

BaseTable[nIndex + 5] = chrTemp;

chrTemp = BaseTable[nIndex + 1];

BaseTable[nIndex + 1] = BaseTable[nIndex + 6];

BaseTable[nIndex + 6] = chrTemp;

chrTemp = BaseTable[nIndex + 2];

BaseTable[nIndex + 2] = BaseTable[nIndex + 7];

BaseTable[nIndex + 7] = chrTemp;

chrTemp = BaseTable[nIndex + 3];

BaseTable[nIndex + 3] = BaseTable[nIndex + 4];

BaseTable[nIndex + 4] = chrTemp;

}

break;

case 7:

// Exechange 0 <--> 6, 1 <--> 7, 2 <--> 4, 3 <--> 5

for( int i = 0; i < BaseTable.Length / CREATE_TYPE; i++ )

{

nIndex = i * CREATE_TYPE;

chrTemp = BaseTable[nIndex];

BaseTable[nIndex] = BaseTable[nIndex + 6];

BaseTable[nIndex + 6] = chrTemp;

chrTemp = BaseTable[nIndex + 1];

BaseTable[nIndex + 1] = BaseTable[nIndex + 7];

BaseTable[nIndex + 7] = chrTemp;

chrTemp = BaseTable[nIndex + 2];

BaseTable[nIndex + 2] = BaseTable[nIndex + 4];

BaseTable[nIndex + 4] = chrTemp;

chrTemp = BaseTable[nIndex + 3];

BaseTable[nIndex + 3] = BaseTable[nIndex + 5];

BaseTable[nIndex + 5] = chrTemp;

}

break;

default:

break;

}

return BaseTable;

}

///

/// Encode string at specific parameter

///

///

///

/// return encoded string

public char[] GetEncoded( char[] Para, byte[] input )

{

length=input.Length;

if((length % 3)==0)

{

paddingCount=0;

blockCount=length/3;

}

else

{

paddingCount=3-(length % 3);//need to add padding

blockCount=(length+paddingCount) / 3;

}

length2=length+paddingCount;//or blockCount *3

byte[] source2;

source2=new byte[length2];

//copy data over insert padding

for (int x=0; x

{

if (x

{

source2[x]=input[x];

}

else

{

source2[x]=0;

}

}

byte b1, b2, b3;

byte temp, temp1, temp2, temp3, temp4;

byte[] buffer=new byte[blockCount*4];

char[] result=new char[blockCount*4];

for (int x=0;x

{

b1=source2[x*3];

b2=source2[x*3+1];

b3=source2[x*3+2];

temp1=(byte)((b1 & 252)>>2);//first

temp=(byte)((b1 & 3)<<4);

temp2=(byte)((b2 & 240)>>4);

temp2+=temp; //second

temp=(byte)((b2 & 15)<<2);

temp3=(byte)((b3 & 192)>>6);

temp3+=temp; //third

temp4=(byte)(b3 & 63); //fourth

buffer[x*4]=temp1;

buffer[x*4+1]=temp2;

buffer[x*4+2]=temp3;

buffer[x*4+3]=temp4;

}

lookupTable = CreateBase64Char( ref Para );

for (int x=0; x

{

result[x]=sixbit2char(buffer[x]);

}

//covert last "A"s to "=", based on paddingCount

switch (paddingCount)

{

case 0:break;

case 1:result[blockCount*4-1]='=';break;

case 2:result[blockCount*4-1]='=';

result[blockCount*4-2]='=';

break;

default:break;

}

return result;

}

private char sixbit2char(byte b)

来自 “ ITPUB博客 ” ，链接：https://blog.itpub.net/374079/viewspace-130595/ ，如需转载，请注明出处，否则将追究法律责任。

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