idea.cpp

利用网络信息加密技术实现电子邮件的安全传输。

// Idea.cpp: implementation of the CIdea class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "MailEncrypt.h"
#include "Idea.h"

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

//以下实现组成二和组成三
/////////////////////////////////////////////////////////////

///////////////////////////
////组成二////
//加密和解密用到的私有方法
///////////////////////////

  
    //加密方法用到的私有方法的实现	

 
	//[1].
	//作用：生成加密子的密钥
    void CIdea::en_key_idea(bit8 *userkey, bit16 *Z)
	{
	    int i,j;

	    for (j=0; j<8; j++)
		{
		    Z[j] = (userkey[0]<<8) + userkey[1];
		    userkey+=2;
		}

	    for (i=0; j<KEYLEN; j++)
		{
			i++;
		    Z[i+7] = Z[i & 7] << 9 | Z[i+1 & 7] >> 7;
		    Z += i & 8;
		    i &= 7;
		}
	}   
   
  	//[2]. 
	//乘法求逆
	bit16 CIdea::inv(bit16 x)     
	{
	    bit16 t0, t1;
	    bit16 q, y;

	    if (x <= 1)
		    return x;
	    t1 = 0x10001L / x;
	    y = 0x10001L % x;
	    if (y == 1)
		    return low16(1-t1);
	    t0 = 1;
	    
		do
		{	
		    q = x / y;
		    x = x % y;
		    t0 += q * t1;
		    if (x == 1)
			    return t0;
		    q = y / x;
		    y = y % x;
		    t1 += q * t0;
		} while (y != 1);
	    return low16(1-t1);
	} 
 
	//[3].
	//作用：生成解密的子密钥
	//      调用了[2].
    void CIdea:: de_key_idea(bit16* Z, bit16* DK)
    {
   	 int j;
	 bit16 t1, t2, t3;
	 bit16 temp[KEYLEN];
	 bit16 *p = temp+ KEYLEN;

	 t1 = inv(*Z++);
	 t2 = -*Z++;
	 t3 = -*Z++;
	 *--p = inv(*Z++);
	 *--p = t3;
	 *--p = t2;
	 *--p = t1;

	 for (j = 1; j < ROUNDS; j++)
	 {
		t1 = *Z++;
		*--p = *Z++;
		*--p = t1;

		t1 = inv(*Z++);
		t2 = -*Z++;
		t3 = -*Z++;
		*--p = inv(*Z++);
		*--p = t2;
		*--p = t3;
		*--p = t1;
	 }
	 t1 = *Z++;
	 *--p = *Z++;
	 *--p = t1;

	 t1 = inv(*Z++);
	 t2 = -*Z++;
	 t3 = -*Z++;
	 *--p = inv(*Z++);
	 *--p = t3;
	 *--p = t2;
	 *--p = t1;

	 
	for (j=0; j<KEYLEN; j++)
	{
	 
		DK[j]=temp[j];
	  
	}
	
	
	
}


   	//[4].
    //乘法
    bit16 CIdea::mul(bit16 a,bit16 b)
	{
	     bit32 p;

	     if (a)
		 {
			 if (b)
			 {	
		         p = (bit32)a * b;
			     b = low16(p);
			     a = p>>16;
			     return b - a + (b < a);
			 }
		     else
			 {
			     return 1-a;
			 }
		 }
 	     else
		 {	
		     return 1-b;
		 }
	}

	//[5].
	//作用：加密,解密64Bit
    //      调用了[4].
	void CIdea::cipher_idea(bit8* bu1, bit8* bu2,bit16* Z)
	{
         bit16 x1, x2, x3, x4, s2, s3;
 	     int r = ROUNDS;
         bit16 *in, *out;
	     in=(bit16 *)bu1;
	     x1 = *in++;
	     x2 = *in++;
	     x3 = *in++;
	     x4 = *in;
	
	     do 
		 {
		     MUL(x1,*Z++);
		     x2 += *Z++;
		     x3 += *Z++;
		     MUL(x4, *Z++);

		     s3 = x3;
		     x3 ^= x1;
		     MUL(x3, *Z++);
		     s2 = x2;
		     x2 ^= x4;
		     x2 += x3;
		     MUL(x2, *Z++);
		     x3 += x2;

		     x1 ^= x2;
		     x4 ^= x3;

		     x2 ^= s3;
		     x3 ^= s2;
		 } while (--r);
	     MUL(x1, *Z++);
	     out=(bit16 *)bu2;
	     *out++ = x1;
         *out++ = x3 + *Z++;
	     *out++ = x2 + *Z++;
	     MUL(x4, *Z);
	     *out = x4;
}

		   //[6].
	   //利用随机种子生成对称密钥
       //   同时修改随机种子的函数
	   void CIdea::MakeRadomKey(unsigned char*)
	   {

		    //先得到字符串型的随机种子

			//化字符串型的随机种子成8字节字符串
			//unsigned char  RadomKeyString[8];
			//（ 必要时可利用DES中的sbox()函数 ）

			//利用IDEA类的加密字符串函数加密此字符串
			//生成对称密钥（8字节）
		    //注：此时的密钥为随机种子成8字节字符串的两次
		    //    （或经适当的变化）
			//赋给charkey1
		    //CIdea idea;
		    //idea.SetKey();
			//idea.EnString(RadomKeyString,charkey1);
			
		    //再来一次得到charkey2

		    //合并charkey1和charkey2成charkey

			//利用IDEA类的解密字符串函数
			//修改随机种子化成的8字节字符串
			//unsigned char temp[8];
			//idea.DeString(RadomKeyString,temp);
			
			//化8字节字符串的随机种子成
			//原来的字符串型的随机种子
			//即从temp到RadomkeyString
			
	   }

	
  
//////////////
////组成三////
//////////////
	      
			//加密方法的实现    
	   	   int CIdea::IdeaEncrypt(char *infilename,
						           char *outfilename)
		   {			
					  //在测示版中
			            //密钥为用户输入
			          //而在正示版中
			          //要利用随机种子生成对称密钥
			          //MakeRadomKey(UserKey);
			   		   
			           //生成加密子密钥
			           en_key_idea(UserKey, EnSubKeys);
									   
				       //进行加密,包括3步			
                         //第1步:打开文件

					   FILE *fin;
					   FILE *fout;
                        
					   if( (fin=fopen(infilename,"rb")) == NULL)
					   {
							MessageBox(NULL,
										"不能打开源文件",
										"出错",
										MB_ICONSTOP|MB_OKCANCEL);
							return  CAN_NOT_OPEN_SOURCE_FILE;
					   }

					   if( (fout=fopen(outfilename,"wb")) == NULL )
					   {
							MessageBox(NULL,
										"不能打开目标文件",
										"出错",
										MB_ICONSTOP|MB_OKCANCEL);
							return  CAN_NOT_OPEN_DIRECT_FILE;
					   }

					   //第2步
					   //进行循环加密
	                     //从文件中得到未加密的8个字符放于字符数组pBuffer内
		                 //如果得到8个字符
		                 //则可以直接IDEA加密
		                 //如果因文件结束而得到的不够8个字符
		                 //则用空字符凑成8个字符后再IDEA加密
	                     //IDEA加密之后的字符数组存储在pBuffer内
		                 //然后把pBuffer存储到加密后的文件中
		                 //我们把加密后的文件存储成文本文件
                       
 		               int i;
					   unsigned char bu1[8]={'\0','\0','\0','\0','\0','\0','\0','\0'};
                       unsigned char bu2[8]={'\0','\0','\0','\0','\0','\0','\0','\0'};
					   
					   while( ( !feof(fin) ) )
					   {
						   						                             
						   i=-1;
			               while( (i<7 ) && ( !feof(fin)) ) 
						   {	
	                              i++;
				                  fread(&bu1[i],sizeof(unsigned char),1,fin);
								 								 
						   }   
							
						   //i=0时表示为8位
						   if (i==0)
							   break;
						  
						   if(feof(fin))
						   {
			                  for(int j=i;j<8;j++)
							  {
			                      bu1[j]=(unsigned char) ('\0');
							  }
			      
				              //用到了[4].
							  cipher_idea( bu1, bu2,EnSubKeys);
                                               
				              //以下把加密后的字符数组存储到加密后的文件中 
		                      for (i=0;i<8;i++)
							  {
		                          fwrite(&bu2[i],sizeof(unsigned char),1,fout);
							  }
				  
				              break; 
						   }

			               cipher_idea( bu1, bu2,EnSubKeys);
                                       		            
			               //以下把加密后的字符数组存储到加密后的文件中 
		                   for (i=0;i<8;i++)
						   {
		                        fwrite(&bu2[i],sizeof(unsigned char),1,fout);
									
						   }

					   }

                     //第3步.
		               //关闭文件
                       fclose(fin);
		               fclose(fout);

					   return SUCCESS;
		   }
			 

    
  	//解密方法的实现

		   int  CIdea::IdeaDecrypt(char *infilename,
			                        char *outfilename)
		   {

			    //生成解密子密钥
			   	en_key_idea(UserKey, EnSubKeys);
		        de_key_idea(EnSubKeys, DeSubKeys);       
			   
				//进行解密:包括3步
						
		           //第1步	
			         //打开文件
					 FILE *fin;
                     FILE *fout;

                     
					 if( (fin=fopen(infilename,"rb")) == NULL)
					 {
							MessageBox(NULL,
										"不能打开源文件",
										"出错",
										MB_ICONSTOP|MB_OKCANCEL);
							return  CAN_NOT_OPEN_SOURCE_FILE;
					 }

					 if( (fout=fopen(outfilename,"wb")) == NULL )
					 {
							MessageBox(NULL,
										"不能打开目标文件",
										"出错",
										MB_ICONSTOP|MB_OKCANCEL);
							return  CAN_NOT_OPEN_DIRECT_FILE;
					 }

					 //第2步
					   //进行循环解密
 					   //以下的处理同加密时的处理
			           //但由于这时的文件的长度已经为8的倍数了
			           //因次不必进行加空字符的处理了
            				 			
 		             int i;
					 unsigned char bu1[8]={'\0','\0','\0','\0','\0','\0','\0','\0'};
                     unsigned char bu2[8]={'\0','\0','\0','\0','\0','\0','\0','\0'};
					 
					 while(! feof (fin))
					 {
			              
		    	      	  
						  i=-1;
			              while( (i < 7 ) && (! feof (fin)) )
						  {
	                           i++;
		                       fread(&bu1[i],sizeof(unsigned char),1,fin);
						  }
						  
						  //i=0时表示为8位
			              if(i==0)
							break;
						  
			              cipher_idea( bu1, bu2,DeSubKeys);
                    
	                      for(i=0;i<8;i++)
						  {
				 
		                        fwrite(&bu2[i],sizeof(unsigned char),1,fout);
				 
						  }	    

					 }  
    	    
					 //第3步
		             //关闭文件
			         fclose(fin);
			         fclose(fout);          
				    
					 return SUCCESS;
		   }

		   
		//加密字符串的方法              
		void CIdea::EnString(unsigned char* before,unsigned char* after)
		{
			int i;

			//首先要产生随机密钥
			MakeRadomKey(UserKey);
			en_key_idea(UserKey,EnSubKeys);

			//先得到字符串的长度length
			int length=strlen((const char*)before);

			//复制一个before
			
			unsigned char *tempbefore=new unsigned char[length];
			unsigned char *tempafter=new unsigned char[length];
			
			//用空字符补成的8倍数的长度
			for(i=0; i<length+8-length%8; i++)
			{
				tempbefore[i]='\0';
				tempafter[i]='\0';
			}
			
			for(i=0; i<length; i++)
			{
				tempbefore[i]=before[i];
			}
							
			//进行加密
			unsigned char buf1[8];
			unsigned char buf2[8];
			
			for(i=0; i<length/8 + 1; i++)
			{
				int j;
				for (j=0; j<8; j++)
				{
					buf1[j]=tempbefore[8*i+j];
				}

				cipher_idea(buf1,buf2,EnSubKeys);
				
				for (j=0; j<8; j++)
				{
					tempafter[8*i+j]=buf2[j];
				}

			}

			//返回加密结果
			for (i=0; i<length; i++)
			{
				after[i]=tempafter[i];
			}
		}

		//解密字符串的方法              
		void CIdea::DeString(unsigned char* before,unsigned char* after)
		{
			int i;

			//先得到字符串的长度length
			int length=strlen((const char*)before);

			//复制一个before
			unsigned char *tempbefore;
			unsigned char *tempafter;

			//用空字符补成的8倍数的长度
			for(i=0; i<length+8-length%8; i++)
			{
				tempbefore[i]='\0';
				tempafter[i]='\0';
			}

			for(i=0; i<length; i++)
			{
				tempbefore[i]=before[i];
			}			
			
			//进行解密
			unsigned char buf1[8];
			unsigned char buf2[8];
			
			for(i=0; i<length/8 + 1; i++)
			{
				int j;
				for (j=0; j<8; j++)
				{
					buf1[j]=tempbefore[8*i+j];
				}

				cipher_idea(buf1,buf2,DeSubKeys);
				
				for (j=0; j<8; j++)
				{
					tempafter[8*i+j]=buf2[j];
				}

			}

            for (i=0; i<length; i++)
			{
				after[i]=tempafter[i];
			}
		
		}

		//设置密钥的方法
		void CIdea::SetKey(unsigned char * charkey)
		{
			int bb;
			for(bb=0; bb<16; bb++)
			{
				UserKey[bb]=charkey[bb];
			}
		}

		//返回密钥的方法
		void CIdea::GetKey(unsigned char * charkey)
		{
			int dd;
			for(dd=0; dd<16; dd++)
			{
				charkey[dd]=UserKey[dd];
			}
		}