程式師世界 >> 編程語言 >> C語言 >> 關於C語言 >> 如何使用C語言獲取文件的SHA1哈希值

如何使用C語言獲取文件的SHA1哈希值

編輯：關於C語言

安全哈希算法（Secure Hash Algorithm）主要適用於數字簽名標准（Digital Signature Standard DSS）裡面定義的數字簽名算法（Digital Signature Algorithm DSA）。對於長度小於2^64位的消息，SHA1會產生一個160位的消息摘要。當接收到消息的時候，這個消息摘要可以用來驗證數據的完整性。在傳輸的過程中，數據很可能會發生變化，那麼這時候就會產生不同的消息摘要。 SHA1有如下特性：不可以從消息摘要中復原信息；兩個不同的消息不會產生同樣的消息摘要。

SHA1 C語言實現

#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  
}

控制台調用函數：

/*輸出文件的SHA1值 
* FileNameInPut:文件路徑 
*/
void GetFileSHA1(char *FileNameInPut)  
{  
    if(FileNameInPut==NULL)   
    {  
        printf("\nUsage:\n     <EXEFILE> <FILENAME>\n ");  
        return;  
    }  
    FILE *fp;  
    char buffer[4096];  
    size_t n;  
    SHA1_CONTEXT ctx;  
    int i;  
       
    fopen_s (&fp, FileNameInPut, "rb");  
    if (!fp)              
    {  
        printf("打開文件“%s”失敗\n", FileNameInPut);  
        return;  
    }  
    sha1_init (&ctx);  
    while ( (n = fread (buffer, 1, sizeof buffer, fp)))     sha1_write (&ctx, (unsigned char *)buffer, n);  
    if (ferror (fp))  
    {  
        printf("讀取文件“%s”失敗\n", FileNameInPut);  
        return;  
    }  
    sha1_final (&ctx);  
    fclose (fp);  
       
    for ( i=0; i < 20; i++)  
    {  
        printf("%02x",ctx.buf[i]);  
    }  
}

適合程序中調用的返回值方式：

/*獲取文件的SHA1值，如果發生錯誤則將錯誤信息寫入outError 
* FileNameInPut:文件路徑 
* outSHA1:SHA1輸出變量 
* outError:錯誤信息輸出變量 
* 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, "打開文件“%s”失敗\n", 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, "讀取文件“%s”失敗\n", 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] = '\0';  
    return outSHA1;  
}

水平有限，此方法只是簡單的實現，還有些問題沒有解決，希望高手指點一二，小弟不勝感激！

用法示例：

//用法實例：  
int main (int argc, char **argv)  
{  
    GetFileSHA1(*(argv+1));  
       
    printf("\r\n");  
    char sha1[41] = { 0 };  
    char eror[256] = { 0 };  
    printf("%s\r\n", GetFileSHA1(*(argv+1), sha1, NULL));  
    if (strlen(eror) != 0)  
    {  
        printf("獲取SHA1發生錯誤：%s\r\n", eror);  
    }  
       
    printf("%s\r\n", GetFileSHA1(*(argv+1), sha1, eror));  
    if (strlen(eror) != 0)  
    {  
        printf("獲取SHA1發生錯誤：%s\r\n", eror);  
    }  
    getchar();  
    return 0;  
}