C语言获取文件SHA1哈希

安全散列算法（Secure Hash Algorithm）主要适用于数字签名标准 （Digital Signature Standard DSS）它定义了数字签名算法（Digital Signature Algorithm DSA）。对于长度小于2^64位的消息。SHA1会产生一个160位的消息摘要。当接收到消息的时候，这个消息摘要能够用来验证数据的完整性。

在传输的过程中。数据非常可能会发生变化，那么这时候就会产生不同的消息摘要。

SHA1有例如以下特性：不能够从消息摘要中复原信息。两个不同的消息不会产生相同的消息摘要。

SHA1 C语言实现

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <errno.h>

#undef BIG_ENDIAN_HOST
typedef unsigned int u32;

/****************
* Rotate a 32 bit integer by n bytes
*/
#if defined(__GNUC__) && defined(__i386__)
static inline u32
	rol( u32 x, int n)
{
	__asm__("roll %%cl,%0"
		:"=r" (x)
		:"0" (x),"c" (n));
	return x;
}
#else
#define rol(x,n) ( ((x) << (n)) | ((x) >> (32-(n))) )
#endif


typedef struct {
	u32  h0,h1,h2,h3,h4;
	u32  nblocks;
	unsigned char buf[64];
	int  count;
} SHA1_CONTEXT;



void
	sha1_init( SHA1_CONTEXT *hd )
{
	hd->h0 = 0x67452301;
	hd->h1 = 0xefcdab89;
	hd->h2 = 0x98badcfe;
	hd->h3 = 0x10325476;
	hd->h4 = 0xc3d2e1f0;
	hd->nblocks = 0;
	hd->count = 0;
}


/****************
* Transform the message X which consists of 16 32-bit-words
*/
static void
	transform( SHA1_CONTEXT *hd, unsigned char *data )
{
	u32 a,b,c,d,e,tm;
	u32 x[16];

	/* get values from the chaining vars */
	a = hd->h0;
	b = hd->h1;
	c = hd->h2;
	d = hd->h3;
	e = hd->h4;

#ifdef BIG_ENDIAN_HOST
	memcpy( x, data, 64 );
#else
	{
		int i;
		unsigned char *p2;
		for(i=0, p2=(unsigned char*)x; i < 16; i++, p2 += 4 ) 
		{
			p2[3] = *data++;
			p2[2] = *data++;
			p2[1] = *data++;
			p2[0] = *data++;
		}
	}
#endif


#define K1  0x5A827999L
#define K2  0x6ED9EBA1L
#define K3  0x8F1BBCDCL
#define K4  0xCA62C1D6L
#define F1(x,y,z)   ( z ^ ( x & ( y ^ z ) ) )
#define F2(x,y,z)   ( x ^ y ^ z )
#define F3(x,y,z)   ( ( x & y ) | ( z & ( x | y ) ) )
#define F4(x,y,z)   ( x ^ y ^ z )


#define M(i) ( tm =   x[i&0x0f] ^ x[(i-14)&0x0f] 
	^ x[(i-8)&0x0f] ^ x[(i-3)&0x0f] 
	, (x[i&0x0f] = rol(tm,1)) )

#define R(a,b,c,d,e,f,k,m)  do { e += rol( a, 5 )     
	+ f( b, c, d )  
	+ k	      
	+ m;	      
	b = rol( b, 30 );    
	} while(0)
	R( a, b, c, d, e, F1, K1, x[ 0] );
	R( e, a, b, c, d, F1, K1, x[ 1] );
	R( d, e, a, b, c, F1, K1, x[ 2] );
	R( c, d, e, a, b, F1, K1, x[ 3] );
	R( b, c, d, e, a, F1, K1, x[ 4] );
	R( a, b, c, d, e, F1, K1, x[ 5] );
	R( e, a, b, c, d, F1, K1, x[ 6] );
	R( d, e, a, b, c, F1, K1, x[ 7] );
	R( c, d, e, a, b, F1, K1, x[ 8] );
	R( b, c, d, e, a, F1, K1, x[ 9] );
	R( a, b, c, d, e, F1, K1, x[10] );
	R( e, a, b, c, d, F1, K1, x[11] );
	R( d, e, a, b, c, F1, K1, x[12] );
	R( c, d, e, a, b, F1, K1, x[13] );
	R( b, c, d, e, a, F1, K1, x[14] );
	R( a, b, c, d, e, F1, K1, x[15] );
	R( e, a, b, c, d, F1, K1, M(16) );
	R( d, e, a, b, c, F1, K1, M(17) );
	R( c, d, e, a, b, F1, K1, M(18) );
	R( b, c, d, e, a, F1, K1, M(19) );
	R( a, b, c, d, e, F2, K2, M(20) );
	R( e, a, b, c, d, F2, K2, M(21) );
	R( d, e, a, b, c, F2, K2, M(22) );
	R( c, d, e, a, b, F2, K2, M(23) );
	R( b, c, d, e, a, F2, K2, M(24) );
	R( a, b, c, d, e, F2, K2, M(25) );
	R( e, a, b, c, d, F2, K2, M(26) );
	R( d, e, a, b, c, F2, K2, M(27) );
	R( c, d, e, a, b, F2, K2, M(28) );
	R( b, c, d, e, a, F2, K2, M(29) );
	R( a, b, c, d, e, F2, K2, M(30) );
	R( e, a, b, c, d, F2, K2, M(31) );
	R( d, e, a, b, c, F2, K2, M(32) );
	R( c, d, e, a, b, F2, K2, M(33) );
	R( b, c, d, e, a, F2, K2, M(34) );
	R( a, b, c, d, e, F2, K2, M(35) );
	R( e, a, b, c, d, F2, K2, M(36) );
	R( d, e, a, b, c, F2, K2, M(37) );
	R( c, d, e, a, b, F2, K2, M(38) );
	R( b, c, d, e, a, F2, K2, M(39) );
	R( a, b, c, d, e, F3, K3, M(40) );
	R( e, a, b, c, d, F3, K3, M(41) );
	R( d, e, a, b, c, F3, K3, M(42) );
	R( c, d, e, a, b, F3, K3, M(43) );
	R( b, c, d, e, a, F3, K3, M(44) );
	R( a, b, c, d, e, F3, K3, M(45) );
	R( e, a, b, c, d, F3, K3, M(46) );
	R( d, e, a, b, c, F3, K3, M(47) );
	R( c, d, e, a, b, F3, K3, M(48) );
	R( b, c, d, e, a, F3, K3, M(49) );
	R( a, b, c, d, e, F3, K3, M(50) );
	R( e, a, b, c, d, F3, K3, M(51) );
	R( d, e, a, b, c, F3, K3, M(52) );
	R( c, d, e, a, b, F3, K3, M(53) );
	R( b, c, d, e, a, F3, K3, M(54) );
	R( a, b, c, d, e, F3, K3, M(55) );
	R( e, a, b, c, d, F3, K3, M(56) );
	R( d, e, a, b, c, F3, K3, M(57) );
	R( c, d, e, a, b, F3, K3, M(58) );
	R( b, c, d, e, a, F3, K3, M(59) );
	R( a, b, c, d, e, F4, K4, M(60) );
	R( e, a, b, c, d, F4, K4, M(61) );
	R( d, e, a, b, c, F4, K4, M(62) );
	R( c, d, e, a, b, F4, K4, M(63) );
	R( b, c, d, e, a, F4, K4, M(64) );
	R( a, b, c, d, e, F4, K4, M(65) );
	R( e, a, b, c, d, F4, K4, M(66) );
	R( d, e, a, b, c, F4, K4, M(67) );
	R( c, d, e, a, b, F4, K4, M(68) );
	R( b, c, d, e, a, F4, K4, M(69) );
	R( a, b, c, d, e, F4, K4, M(70) );
	R( e, a, b, c, d, F4, K4, M(71) );
	R( d, e, a, b, c, F4, K4, M(72) );
	R( c, d, e, a, b, F4, K4, M(73) );
	R( b, c, d, e, a, F4, K4, M(74) );
	R( a, b, c, d, e, F4, K4, M(75) );
	R( e, a, b, c, d, F4, K4, M(76) );
	R( d, e, a, b, c, F4, K4, M(77) );
	R( c, d, e, a, b, F4, K4, M(78) );
	R( b, c, d, e, a, F4, K4, M(79) );

	/* Update chaining vars */
	hd->h0 += a;
	hd->h1 += b;
	hd->h2 += c;
	hd->h3 += d;
	hd->h4 += e;
}


/* Update the message digest with the contents
* of INBUF with length INLEN.
*/
static void
	sha1_write( SHA1_CONTEXT *hd, unsigned char *inbuf, size_t inlen)
{
	if( hd->count == 64 ) { /* flush the buffer */
		transform( hd, hd->buf );
		hd->count = 0;
		hd->nblocks++;
	}
	if( !inbuf )
		return;
	if( hd->count ) {
		for( ; inlen && hd->count < 64; inlen-- )
			hd->buf[hd->count++] = *inbuf++;
		sha1_write( hd, NULL, 0 );
		if( !inlen )
			return;
	}

	while( inlen >= 64 ) {
		transform( hd, inbuf );
		hd->count = 0;
		hd->nblocks++;
		inlen -= 64;
		inbuf += 64;
	}
	for( ; inlen && hd->count < 64; inlen-- )
		hd->buf[hd->count++] = *inbuf++;
}


/* The routine final terminates the computation and
* returns the digest.
* The handle is prepared for a new cycle, but adding bytes to the
* handle will the destroy the returned buffer.
* Returns: 20 bytes representing the digest.
*/

static void
	sha1_final(SHA1_CONTEXT *hd)
{
	u32 t, msb, lsb;
	unsigned char *p;

	sha1_write(hd, NULL, 0); /* flush */;

	t = hd->nblocks;
	/* multiply by 64 to make a byte count */
	lsb = t << 6;
	msb = t >> 26;
	/* add the count */
	t = lsb;
	if( (lsb += hd->count) < t )
		msb++;
	/* multiply by 8 to make a bit count */
	t = lsb;
	lsb <<= 3;
	msb <<= 3;
	msb |= t >> 29;

	if( hd->count < 56 ) { /* enough room */
		hd->buf[hd->count++] = 0x80; /* pad */
		while( hd->count < 56 )
			hd->buf[hd->count++] = 0;  /* pad */
	}
	else { /* need one extra block */
		hd->buf[hd->count++] = 0x80; /* pad character */
		while( hd->count < 64 )
			hd->buf[hd->count++] = 0;
		sha1_write(hd, NULL, 0);  /* flush */;
		memset(hd->buf, 0, 56 ); /* fill next block with zeroes */
	}
	/* append the 64 bit count */
	hd->buf[56] = msb >> 24;
	hd->buf[57] = msb >> 16;
	hd->buf[58] = msb >>  8;
	hd->buf[59] = msb	   ;
	hd->buf[60] = lsb >> 24;
	hd->buf[61] = lsb >> 16;
	hd->buf[62] = lsb >>  8;
	hd->buf[63] = lsb	   ;
	transform( hd, hd->buf );

	p = hd->buf;
#ifdef BIG_ENDIAN_HOST
#define X(a) do { *(u32*)p = hd->h##a ; p += 4; } while(0)
#else /* little endian */
#define X(a) do { *p++ = hd->h##a >> 24; *p++ = hd->h##a >> 16;	 
	*p++ = hd->h##a >> 8; *p++ = hd->h##a; } while(0)
#endif
	X(0);
	X(1);
	X(2);
	X(3);
	X(4);
#undef X
}

控制台调用函数：

/*输出文件的SHA1值
* FileNameInPut:文件路径
*/
void GetFileSHA1(char *FileNameInPut)
{
	if(FileNameInPut==NULL) 
	{
		printf("
Usage:
     <EXEFILE> <FILENAME>
 ");
		return;
	}
	FILE *fp;
	char buffer[4096];
	size_t n;
	SHA1_CONTEXT ctx;
	int i;

	fopen_s (&fp, FileNameInPut, "rb");
	if (!fp)			
	{
		printf("打开文件“%s”失败
", FileNameInPut);
		return;
	}
	sha1_init (&ctx);
	while ( (n = fread (buffer, 1, sizeof buffer, fp)))		sha1_write (&ctx, (unsigned char *)buffer, n);
	if (ferror (fp))
	{
		printf("读取文件“%s”失败
", FileNameInPut);
		return;
	}
	sha1_final (&ctx);
	fclose (fp);

	for ( i=0; i < 20; i++)
	{
		printf("%02x",ctx.buf[i]);
	}
}

适合程序中调用的返回值方式：

/*获取文件的SHA1值，假设错误发生则将错误信息写入outError
* FileNameInPut:文件路径
* outSHA1:SHA1输出变量
* outError:错误信息输出变量
* returns:outSHA1
*/
char *GetFileSHA1(char *FileNameInPut, char *outSHA1, char *outError)
{
	if(FileNameInPut==NULL) 
	{
		if (outError != NULL)
		{
			sprintf(outError, "%s", "FileNameInPut Is NULL");
		}
		return outSHA1;
	}
	FILE *fp;
	char buffer[4096];
	size_t n;
	SHA1_CONTEXT ctx;
	int i;

	fopen_s (&fp, FileNameInPut, "rb");
	if (!fp)			
	{
		if (outError != NULL)
		{
			sprintf(outError, "打开文件“%s”失败
", FileNameInPut);
		}
		return outSHA1;
	}
	sha1_init (&ctx);
	while ( (n = fread (buffer, 1, sizeof buffer, fp)))		sha1_write (&ctx, (unsigned char *)buffer, n);
	if (ferror (fp))
	{
		if (outError != NULL)
		{
			sprintf(outError, "读取文件“%s”失败
", FileNameInPut);
		}
		return outSHA1;
	}
	sha1_final (&ctx);
	fclose (fp);

	for ( i=0; i < 20; i++)
	{
		sprintf(outSHA1 + 2*i, "%02x", (unsigned char)ctx.buf[i]);
	}
	outSHA1[2*i] = '';
	return outSHA1;
}

水平有限，此方法仅仅是简单的实现，还有些问题没有解决，希望高手指点一二。小弟不胜感激！

使用方法演示样例：

//使用方法实例：
int main (int argc, char **argv)
{
	GetFileSHA1(*(argv+1));

	printf("
");
	char sha1[41] = { 0 };
	char eror[256] = { 0 };
	printf("%s
", GetFileSHA1(*(argv+1), sha1, NULL));
	if (strlen(eror) != 0)
	{
		printf("获取SHA1错误发生：%s
", eror);
	}

	printf("%s
", GetFileSHA1(*(argv+1), sha1, eror));
	if (strlen(eror) != 0)
	{
		printf("获取SHA1错误发生：%s
", eror);
	}
	getchar();
	return 0;
}

命令提示符下使用方法：

源代码下载：http://download.csdn.net/detail/testcs_dn/7332933

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