md5.cpp

这是一个在vc环境下编译通过的MD5算法。包含算法源代码和测试主程序。

/******************************************************************************
                        MD5C.C : MD5 报文摘要算法
*******************************************************************************/

#include "md5.h"
#include "memory.h"
//预设填充字段
unsigned char PADDING[64] = {
  0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};
ULONG CMD5::LRotate(ULONG Sdata,int nBit)
{
	return (Sdata<<nBit)|(Sdata>>(32-nBit));
}
ULONG CMD5::F(ULONG x,ULONG y,ULONG z)
{
	return (x&y)|((~x)&z);
}
ULONG CMD5::G(ULONG x,ULONG y,ULONG z)
{
	return (x&z)|(y&(~z));
}
ULONG CMD5::H(ULONG x,ULONG y,ULONG z)
{
	return x^y^z;
}
ULONG CMD5::I(ULONG x,ULONG y,ULONG z)
{
	return y^(x|(~z));
}
void CMD5::FF(ULONG &a,ULONG b,ULONG c,ULONG d,ULONG Msg,int nBit,ULONG Cnt)
{
	a+=F(b,c,d)+Msg+(ULONG)Cnt;
	a=LRotate(a,nBit);
	a+=b;
}
void CMD5::GG(ULONG &a,ULONG b,ULONG c,ULONG d,ULONG Msg,int nBit,ULONG Cnt)
{
	a+=G(b,c,d)+Msg+(ULONG)Cnt;
	a=LRotate(a,nBit);
	a+=b;
}
void CMD5::HH(ULONG &a,ULONG b,ULONG c,ULONG d,ULONG Msg,int nBit,ULONG Cnt)
{
	a+=H(b,c,d)+Msg+(ULONG)Cnt;
	a=LRotate(a,nBit);
	a+=b;
}
void CMD5::II(ULONG &a,ULONG b,ULONG c,ULONG d,ULONG Msg,int nBit,ULONG Cnt)
{
	a+=I(b,c,d)+Msg+(ULONG)Cnt;
	a=LRotate(a,nBit);
	a+=b;
}
//初始化链接结构
void CMD5::Init(MD5_CTX *context)
{
	context->count[0] = context->count[1] = 0;
	context->state[0] = 0x67452301;
	context->state[1] = 0xefcdab89;
	context->state[2] = 0x98badcfe;
	context->state[3] = 0x10325476;
}

//进行报文摘要得运算，
void CMD5::Md5(MD5_CTX *context, const unsigned char *input, unsigned int inputLen)
{
	unsigned int i, index, partLen;
    //模64 字节数 
	index = (unsigned int)((context->count[0] >> 3) & 0x3F);

	// 更新填充前信息位数bit
	context->count[0] += ((ULONG)inputLen << 3);
    
	if ( context->count[0]< ((ULONG)inputLen << 3) )
		context->count[1]++;

	context->count[1] += ((ULONG)inputLen >> 29);

	partLen = 64 - index;
	if (inputLen >= partLen)
	{
		memcpy((POINTER)&context->buffer[index], (POINTER)input, partLen);
		Transform (context->state, context->buffer);

		for (i = partLen; i + 63 < inputLen; i += 64)
			Transform (context->state, &input[i]);

		index = 0;
	}
	else
	i = 0;
	//将未处理字节重新写入
	memcpy((POINTER)&context->buffer[index], (POINTER)&input[i], inputLen-i);
}
void CMD5::Final(unsigned char digest[16], MD5_CTX *context)
{
	unsigned char bits[8];
	unsigned int index, padLen;

	//实际信息比特数
	memcpy(bits, context->count, 8);

	//计算填充量，模64
	index = (unsigned int)((context->count[0] >> 3) & 0x3f);
	padLen = (index < 56) ? (56 - index) : (120 - index);
	Md5 (context, PADDING, padLen);

	// 添加信息长度
	Md5(context, bits, 8);

	// 将链接变量存入digest,作为产生得摘要
	memcpy(digest, context->state, 16);
}

//主处理模块 将64字节即512比特数据，转换为4个联接变量或128位摘要 
void CMD5::Transform(ULONG state[4], const unsigned char block[64])
{

	ULONG a = state[0], b = state[1], c = state[2], d = state[3], x[16];
	memcpy (x, block, 64);

	/* Round 1 */
	FF (a, b, c, d, x[ 0], S11, 0xd76aa478); 
	FF (d, a, b, c, x[ 1], S12, 0xe8c7b756); 
	FF (c, d, a, b, x[ 2], S13, 0x242070db); 
	FF (b, c, d, a, x[ 3], S14, 0xc1bdceee);
	FF (a, b, c, d, x[ 4], S11, 0xf57c0faf); 
	FF (d, a, b, c, x[ 5], S12, 0x4787c62a); 
	FF (c, d, a, b, x[ 6], S13, 0xa8304613); 
	FF (b, c, d, a, x[ 7], S14, 0xfd469501); 
	FF (a, b, c, d, x[ 8], S11, 0x698098d8); 
	FF (d, a, b, c, x[ 9], S12, 0x8b44f7af); 
	FF (c, d, a, b, x[10], S13, 0xffff5bb1); 
	FF (b, c, d, a, x[11], S14, 0x895cd7be); 
	FF (a, b, c, d, x[12], S11, 0x6b901122); 
	FF (d, a, b, c, x[13], S12, 0xfd987193); 
	FF (c, d, a, b, x[14], S13, 0xa679438e); 
	FF (b, c, d, a, x[15], S14, 0x49b40821); 
	
	/* Round 2 */
	GG (a, b, c, d, x[ 1], S21, 0xf61e2562); 
	GG (d, a, b, c, x[ 6], S22, 0xc040b340); 
	GG (c, d, a, b, x[11], S23, 0x265e5a51); 
	GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa); 
	GG (a, b, c, d, x[ 5], S21, 0xd62f105d); 
	GG (d, a, b, c, x[10], S22,  0x2441453); 
	GG (c, d, a, b, x[15], S23, 0xd8a1e681); 
	GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8); 
	GG (a, b, c, d, x[ 9], S21, 0x21e1cde6); 
	GG (d, a, b, c, x[14], S22, 0xc33707d6); 
	GG (c, d, a, b, x[ 3], S23, 0xf4d50d87); 
	GG (b, c, d, a, x[ 8], S24, 0x455a14ed); 
	GG (a, b, c, d, x[13], S21, 0xa9e3e905); 
	GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8); 
	GG (c, d, a, b, x[ 7], S23, 0x676f02d9); 
	GG (b, c, d, a, x[12], S24, 0x8d2a4c8a); 
	
	HH (a, b, c, d, x[ 5], S31, 0xfffa3942); 
	HH (d, a, b, c, x[ 8], S32, 0x8771f681); 
	HH (c, d, a, b, x[11], S33, 0x6d9d6122); 
	HH (b, c, d, a, x[14], S34, 0xfde5380c); 
	HH (a, b, c, d, x[ 1], S31, 0xa4beea44); 
	HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9); 
	HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60); 
	HH (b, c, d, a, x[10], S34, 0xbebfbc70); 
	HH (a, b, c, d, x[13], S31, 0x289b7ec6); 
	HH (d, a, b, c, x[ 0], S32, 0xeaa127fa); 
	HH (c, d, a, b, x[ 3], S33, 0xd4ef3085); 
	HH (b, c, d, a, x[ 6], S34,  0x4881d05); 
	HH (a, b, c, d, x[ 9], S31, 0xd9d4d039); 
	HH (d, a, b, c, x[12], S32, 0xe6db99e5); 
	HH (c, d, a, b, x[15], S33, 0x1fa27cf8); 
	HH (b, c, d, a, x[ 2], S34, 0xc4ac5665); 
	
	II (a, b, c, d, x[ 0], S41, 0xf4292244); 
	II (d, a, b, c, x[ 7], S42, 0x432aff97); 
	II (c, d, a, b, x[14], S43, 0xab9423a7); 
	II (b, c, d, a, x[ 5], S44, 0xfc93a039); 
	II (a, b, c, d, x[12], S41, 0x655b59c3); 
	II (d, a, b, c, x[ 3], S42, 0x8f0ccc92); 
	II (c, d, a, b, x[10], S43, 0xffeff47d); 
	II (b, c, d, a, x[ 1], S44, 0x85845dd1); 
	II (a, b, c, d, x[ 8], S41, 0x6fa87e4f); 
	II (d, a, b, c, x[15], S42, 0xfe2ce6e0); 
	II (c, d, a, b, x[ 6], S43, 0xa3014314); 
	II (b, c, d, a, x[13], S44, 0x4e0811a1); 
	II (a, b, c, d, x[ 4], S41, 0xf7537e82); 
	II (d, a, b, c, x[11], S42, 0xbd3af235); 
	II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb); 
	II (b, c, d, a, x[ 9], S44, 0xeb86d391); 

	state[0] += a;
	state[1] += b;
	state[2] += c;
	state[3] += d;
}