C语言获取文件的SHA1哈希值

C语言获取文件的SHA1哈希值

安全哈希算法（Secure Hash Algorithm）主要适用于数字签名标准 （Digital Signature Standard DSS）里面定义的数字签名算法（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，这个消息摘要可以用来验证数据的完整性。在传输的过程中，数据很可能会发生变化，那么这时候就会产生不同的消息摘要。 SHA1有如下特性：不可以从消息摘要中复原信息；两个不同的消息不会产生同样的消息摘要。

将C语言梳理一下，分布在以下10个章节中：

1. Linux-C成长之路（一）：Linux下C编程概要
2. Linux-C成长之路（二）：基本数据类型
3. Linux-C成长之路（三）：基本IO函数操作
4. Linux-C成长之路（四）：运算符
5. Linux-C成长之路（五）：控制流
6. Linux-C成长之路（六）：函数要义
7. Linux-C成长之路（七）：数组与指针
8. Linux-C成长之路（八）：存储类，动态内存
9. Linux-C成长之路（九）：复合数据类型
10. Linux-C成长之路（十）：其他高级议题

C++ Primer Plus 第6版 中文版 清晰有书签PDF+源代码

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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
}

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