test_blowfish.cpp

采用blowfish算法对字符串进行加密和解密

	}
};
const unsigned long pbox[18]=
{
	0x243f6a88, 0x85a308d3, 0x13198a2e, 0x03707344, 0xa4093822, 0x299f31d0, 0x082efa98, 0xec4e6c89, 
		0x452821e6, 0x38d01377, 0xbe5466cf, 0x34e90c6c, 0xc0ac29b7, 0xc97c50dd, 0x3f84d5b5, 0xb5470917, 
		0x9216d5d9, 0x8979fb1b
};
DWORD keybox[18+4*256];

template <class T>
void swap(T& x,T& y)
{
	T temp;
	temp=x;
	x=y;
	y=temp;
}
void BlowfishKeyInit();
unsigned long F(const char Bytes[4]);
void BlowfishEncipher(unsigned long& XL,unsigned long& XR);
void BlowfishDecipher(unsigned long& XL,unsigned long& XR);

void BlowfishKeyInit(char* strKey,int nLen)
{
	/**//////////////////////////////////////
	//把pbox,sbox中的内容复制到keybox中
	unsigned long* pKey=keybox;
	memcpy(pKey,pbox,sizeof(long)*18);
	pKey+=18;
	memcpy(pKey,sbox,sizeof(long)*4*256);

	/**///////////////////////////////////////
	//处理字符串key如果长度不够18*4=72bytes就扩展。
	int i,oldlen=nLen;
	char *cp=NULL;
	if(nLen<72)
	{
		cp=new char[72*2];
		memset(cp,0,sizeof(char)*72*2);
		nLen=0;
		while(nLen<72)
		{
			strcat(cp,strKey);
			nLen+=oldlen;
		}
	}	
	else
		cp=strKey;

	/**////////////////////////////////
	//用已处理的key和keybox中的前18个元素异或(也就是pbox的内容)
	pKey=(unsigned long*)cp;
	for (i=0;i<18;i++)
		keybox[i]^=pKey[i];

	/**////////////////////////////////////////
	//用函数BlowfishEncipher迭代521=((18+256*4)/2)次，初始xl=xr=0,输出用来填充keybox;
	unsigned long xl=0,xr=0;
	for (i=0;i<521;i++)
	{
		BlowfishEncipher(xl,xr);
		keybox[2*i]=xl;
		keybox[2*i+1]=xr;
	}
	printf("\ninitialized!");
}

void BlowfishEncipher(unsigned long& XL,unsigned long& XR)
{
	unsigned long xl=XL,xr=XR,temp=0;
	int i;
	for (i=0;i<16;i++)
	{
		xl^=keybox[i];
		xr^=F((const char*)&xl);
		swap(xl,xr);
	}
	swap(xl,xr);
	xr^=keybox[16];
	xl^=keybox[17];
	XR=xr;
	XL=xl;
}

unsigned long F(const char Bytes[4])
{
	unsigned long temp;
	temp=keybox[SBOX_BEGIN+Bytes[3]]+keybox[SBOX_BEGIN+256+Bytes[2]];
	temp^=keybox[SBOX_BEGIN+256*2+Bytes[1]];
	temp+=keybox[SBOX_BEGIN+256*3+Bytes[0]];
	return temp;
}

void BlowfishDecipher(unsigned long& XL,unsigned long& XR)
{
	unsigned long xl=XL,xr=XR,temp=0;
	int i;
	for (i=17;i>1;i--)
	{
		xl^=keybox[i];
		xr^=F((const char*)&xl);
		swap(xl,xr);
	}
	swap(xl,xr);
	xr^=keybox[1];
	xl^=keybox[0];
	XR=xr;
	XL=xl;	
}

int main(int argc,char* argv[])
{
	char szKey[100]={0};
	char szMessage[100]={0};
	printf("input the key:");
	gets(szKey);
	printf("\nthe key you input is: %s \ninput the message you want to encipher: ",szKey);
	BlowfishKeyInit(szKey,strlen(szKey));
	gets(szMessage);
	printf("\nbefore encipher,the message is: %s ",szMessage);
	int i;
	int len=strlen(szMessage);
	while(len%8!=0)//因为是64bits分组处理，所以字符串的长度必须为8的倍数。
	{
		szMessage[len++]=0;
	}
	for (i=0;i<len;i+=8)
	{
		BlowfishEncipher((unsigned long&)szMessage[i],(unsigned long&)szMessage[i+4]);
	}
	printf("\nthe enciphered message is:");
	for (i=0;i<strlen(szMessage);i++)
		printf("%.2x",(byte)szMessage[i]);
	printf(" ");
	printf("\ndecipher . . . ");
	for (i=0;i<len;i+=8)
	{
		BlowfishDecipher((unsigned long&)szMessage[i],(unsigned long&)szMessage[i+4]);
	}
	printf("\nnow, the message is: %s ",szMessage);
	getchar();
	return 0;			
}