md5.c

LINUX下使用Ansi C编写的MD5消息散列算法

/****************************************************************
 * 程序名: cmppmd5.c											*
 * 编  写: 李祖权												*
 * 时  间: 2004年5月18日										*
 * 作  用: MD5消息摘要程序,CMPP协议用于连接授权					*
 ****************************************************************/

# include	"cmppmd5.h"

# define	S11	 7
# define	S12	12
# define	S13	17
# define	S14	22
# define	S21	 5
# define	S22	 9
# define	S23	14
# define	S24	20
# define	S31	 4
# define	S32	11
# define	S33	16
# define	S34	23
# define	S41	 6
# define	S42	10
# define	S43	15
# define	S44	21

static void		MD5Transform(UINT4 [4], unsigned char [64]);
static void 	Encode(unsigned char *, UINT4 *, unsigned int);
static void 	Decode(UINT4 *, unsigned char *, unsigned int);
static void 	MD5_memcpy(POINTER, POINTER, unsigned int);
static void 	MD5_memset(POINTER, int, unsigned int);

static 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
};

// F, G, H and I are basic MD5 functions.
#define		F(x, y, z)	(((x) & (y)) | ((~x) & (z)))
#define		G(x, y, z)	(((x) & (z)) | ((y) & (~z)))
#define		H(x, y, z)	((x) ^ (y) ^ (z))
#define		I(x, y, z)	((y) ^ ((x) | (~z)))

// ROTATE_LEFT rotates x left n bits.
#define		ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

//FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
//Rotation is separate from addition to prevent recomputation.
# define	FF(a, b, c, d, x, s, ac) { \
		(a) += F ((b), (c), (d)) + (x) + (UINT4)(ac); \
		(a) = ROTATE_LEFT ((a), (s)); \
		(a) += (b); }

# define	GG(a, b, c, d, x, s, ac) { \
		(a) += G ((b), (c), (d)) + (x) + (UINT4)(ac); \
		(a) = ROTATE_LEFT ((a), (s)); \
		(a) += (b); }

# define	HH(a, b, c, d, x, s, ac) { \
		(a) += H ((b), (c), (d)) + (x) + (UINT4)(ac); \
		(a) = ROTATE_LEFT ((a), (s)); \
		(a) += (b); }

# define	II(a, b, c, d, x, s, ac) { \
		(a) += I ((b), (c), (d)) + (x) + (UINT4)(ac); \
		(a) = ROTATE_LEFT ((a), (s)); \
		(a) += (b); }

//初始化数据结构,填允初始值
void MD5Init(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;
}

//MD5 数据块消息摘要操作
void MD5Update (MD5_CTX *context, unsigned char *input,unsigned int inputLen)
{
	unsigned int	i, index, partLen;

	//计算输入块模 64 的字节数
	index = (unsigned int)((context->count[0] >> 3) & 0x3F);

	//更新context中记录的bits数
	if((context->count[0] +=((UINT4)inputLen << 3))<((UINT4)inputLen << 3))
		context->count[1]++;

	context->count[1] += ((UINT4)inputLen >> 29);

	partLen = 64 - index;

	if (inputLen >= partLen) {
		MD5_memcpy((POINTER)&context->buffer[index],
			(POINTER)input,partLen);
		MD5Transform(context->state, context->buffer);

		for (i = partLen; i + 63 < inputLen; i += 64)
			MD5Transform (context->state, &input[i]);

		index = 0;
		}
	else
		i = 0;

	MD5_memcpy((POINTER)&context->buffer[index],
		(POINTER)&input[i],inputLen-i);
}

void MD5Final (unsigned char digest[16], MD5_CTX *context)
{
	unsigned char	bits[8];
	unsigned int	index, padLen;

	//保存长度 bits 数
	Encode (bits, context->count, 8);

	//长度不足,填允
	index = (unsigned int)((context->count[0] >> 3) & 0x3f);
	padLen = (index < 56) ? (56 - index) : (120 - index);
	MD5Update (context, PADDING, padLen);

	//添加长度
	MD5Update (context, bits, 8);

	Encode (digest, context->state, 16);
	MD5_memset ((POINTER)context, 0, sizeof (*context));
}

//MD5 基本处理. 这是基于 512 bits 数据块的处理
static void MD5Transform (UINT4 state[4], unsigned char block[64])
{
	UINT4	a = state[0], b = state[1], c = state[2], d = state[3], x[16];

	Decode (x, block, 64);

	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);

	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;
	MD5_memset ((POINTER)x, 0, sizeof (x));
}

//Encodes 将无符号长整型值转换成字符串, 要求长度 len 是4 的倍数
static void Encode(unsigned char *output, UINT4 *input,unsigned int len)
{
	unsigned int	i, j;

	for (i = 0, j = 0; j < len; i++, j += 4) {
		output[j] = (unsigned char)(input[i] & 0xff);
		output[j+1] = (unsigned char)((input[i] >> 8) & 0xff);
		output[j+2] = (unsigned char)((input[i] >> 16) & 0xff);
		output[j+3] = (unsigned char)((input[i] >> 24) & 0xff); }
}

//Decodes 将无符号串转变为无符号长整形值, 要求长度 len 是4 的倍数
static void Decode (UINT4 *output,unsigned char *input, unsigned int len)
{
	unsigned int	i, j;

	for(i = 0,j = 0;j < len;i++,j += 4)
		output[i]=((UINT4)input[j]) | (((UINT4)input[j+1]) << 8) |
		(((UINT4)input[j+2]) << 16) | (((UINT4)input[j+3]) << 24);
}

static void MD5_memcpy (POINTER output,POINTER input,unsigned int len)
{
	unsigned int	i;

	for (i = 0; i < len; i++) output[i] = input[i];
}

static void MD5_memset (POINTER output,int value,unsigned int len)
{
	unsigned int	i;

	for (i = 0; i < len; i++)
		((char *)output)[i] = (char)value;
}