C# Base64进行加密和解密源码

发布时间：2007年08月27日      浏览次数：3188 次
由于以前文章在介绍Base64方法的时候，所提供的调用方法过于麻烦，而且接口不太直观，因此我最近在原有的基础上进行了修改。

具体代码如下：
//----------------------------- Base64 class --------------------------------------
//---------------------------------------------------------------------------------
//---File: clsBase64
//---Description: The class file to encode string or decode string in base algorithm
//---Author: Knight
//---Created Date: Oct.8, 2005
//---Modified Date: Jul.4, 2006
//---------------------------------------------------------------------------------
//----------------------------{ Base64 class }-------------------------------------
using System;

namespace Base64
{
using System.Text;
/// <summary>
/// Summary description for clsBase64.
/// </summary>
public class clsBase64
{
protected clsBase64()
{
//Avoid to be inited
}

#region Base64_Algorithm_Implement
/// <summary>
/// Create base64 char array using default base64 char array
/// </summary>
/// <param name="CreatePara"></param>
/// <returns>return the new base64 char array</returns>
private static 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;
}


/// <summary>
/// Encode string at specific parameter
/// </summary>
/// <param name="Para"></param>
/// <param name="input"></param>
/// <returns>return encoded string</returns>
private static char[] GetEncoded( char[] Para, byte[] input )
{
char[] lookupTable;
int length, length2;
int blockCount;
int paddingCount;

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<length2;x++)
{
if (x<length)
{
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<blockCount;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<blockCount*4;x++)
{
result[x] = sixbit2char( lookupTable, 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 static char sixbit2char(char[] lookupTable, byte b)
{
if((b>=0) &&(b<=63))
{
return lookupTable[(int)b];
}
else
{
//should not happen;
return ’ ’;
}
}


/// <summary>
/// Decode string using specific parameter
/// </summary>
/// <param name="Para"></param>
/// <param name="input"></param>
/// <returns>If decoded successfully, return the decoded string; else return NULL</returns>
private static byte[] GetDecoded( char[] Para, char[] input )
{
char[] source;
char[] lookupTable;
int length, length2,&nbs, p;length3;
int blockCount;
int paddingCount;

int temp=0;
source = input;
length = input.Length;

if( ( length % 4 ) != 0 ) return null; // The string is not encoded with my base64;

//find how many padding there are
while( input[length - temp - 1] == ’=’ && temp < 3 )
{
temp++;
}
if( temp == 3 ) return null; // The string is not encoded with my base64;

paddingCount=temp;
//calculate the blockCount;
//assuming all whitespace and carriage returns/newline were removed.
blockCount=length/4;
length2=blockCount*3;

byte[] buffer=new byte[length];//first conversion result
byte[] buffer2=new byte[length2];//decoded array with padding

lookupTable = CreateBase64Char( ref Para );
for(int x=0;x<length;x++)
{
buffer[x] = char2sixbit( lookupTable, source[x]);
}

byte b, b1,b2,b3;
byte temp1, temp2, temp3, temp4;

for(int x=0;x<blockCount;x++)
{
temp1=buffer[x*4];
temp2=buffer[x*4+1];
temp3=buffer[x*4+2];
temp4=buffer[x*4+3];

b=(byte)(temp1<<2);
b1=(byte)((temp2 & 48)>>4);
b1+=b;

b=(byte)((temp2 & 15)<<4);
b2=(byte)((temp3 & 60)>>2);
b2+=b;

b=(byte)((temp3 & 3)<<6);
b3=temp4;
b3+=b;

buffer2[x*3]=b1;
buffer2[x*3+1]=b2;
buffer2[x*3+2]=b3;
}
//remove paddings
length3=length2-paddingCount;
byte[] result=new byte[length3];

for(int x=0;x<length3;x++)
{
result[x]=buffer2[x];
}

return result;
}

private static byte char2sixbit( char[] lookupTable, char c)
{
if( c ==’=’ )
return 0;
else
{
for (int x=0;x<64;x++)
{
if (lookupTable[x]==c)
return (byte)x;
}
//should not reach here
return 0;
}
}
#endregion

/// <summary>
/// Encrypt data based on specific key
/// </summary>
/// <param name="Data">the data to be encrypted</param>
/// <param name="Key">key data</param>
/// <returns>If successfully, return encrypted string; else return NULL</returns>
public static string EncryptData( string Data, string Key )
{
if( Data == null || Data == "" ) return null;
if( Key == null || Key == "" ) return null;

char[] chrEncrypted = GetEncoded( Key.ToCharArray(),
Encoding.Unicode.GetBytes( Data ) );

if( chrEncrypted != null )
return new string( chrEncrypted );
else
return null;
}

/// <summary>
/// Decrypt data based on specific key
/// </summary>
/// <param name="Data">the data to be decrypted</param>
/// <param name="Key">key data</param>
/// <returns>If successfully, return decrypted string; else return NULL</returns>
public static string DecryptData( string Data, string Key )
{
if( Data == null || Data == "" ) return null;
if( Key == null || Key == "" ) return null;

byte[] bDecrypted = GetDecoded( Key.ToCharArray(),
Data.ToCharArray() );
if( bDecrypted != null )
return Encoding.Unicode.GetString( bDecrypted );
else
return null;
}

}
}

调用如下：
//Encrypt data
string strEncryptedData = Base64.clsBase64.EncryptData(
yourData, yourKey );

if( strEncryptedData != null )
MessageBox.Show( strEncryptedData );

//Decrypt data
string strDecryptedData = Base64.clsBase64.DecryptData(
yourData, yourKey );

if( strDecryptedData != null )
MessageBox.Show( strDecryptedData );
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