sha2.cpp

计算文件hash值的源代码

/*
 ---------------------------------------------------------------------------
 Copyright (c) 2002, Dr Brian Gladman <[e-mail]>, Worcester, UK.
 All rights reserved.

 LICENSE TERMS

 The free distribution and use of this software in both source and binary 
 form is allowed (with or without changes) provided that:

   1. distributions of this source code include the above copyright 
      notice, this list of conditions and the following disclaimer;

   2. distributions in binary form include the above copyright
      notice, this list of conditions and the following disclaimer
      in the documentation and/or other associated materials;

   3. the copyright holder's name is not used to endorse products 
      built using this software without specific written permission. 

 ALTERNATIVELY, provided that this notice is retained in full, this product
 may be distributed under the terms of the GNU General Public License (GPL),
 in which case the provisions of the GPL apply INSTEAD OF those given above.
 
 DISCLAIMER

 This software is provided 'as is' with no explicit or implied warranties
 in respect of its properties, including, but not limited to, correctness 
 and/or fitness for purpose.
 ---------------------------------------------------------------------------
 Issue Date: 30/11/2002

 This is a byte oriented version of SHA2 that operates on arrays of bytes
 stored in memory. This code implements sha256, sha384 and sha512 but the
 latter two functions rely on efficient 64-bit integer operations that 
 may not be very efficient on 32-bit machines

 The sha256 functions use a type 'sha256_ctx' to hold details of the 
 current hash state and uses the following three calls:

       void sha256_begin(sha256_ctx ctx[1])
       void sha256_hash(const unsigned char data[], 
                            unsigned long len, sha256_ctx ctx[1])
       void sha256_end(unsigned char hval[], sha256_ctx ctx[1])

 The first subroutine initialises a hash computation by setting up the 
 context in the sha256_ctx context. The second subroutine hashes 8-bit 
 bytes from array data[] into the hash state withinh sha256_ctx context, 
 the number of bytes to be hashed being given by the the unsigned long 
 integer len.  The third subroutine completes the hash calculation and 
 places the resulting digest value in the array of 8-bit bytes hval[].

 The sha384 and sha512 functions are similar and use the interfaces:

       void sha384_begin(sha384_ctx ctx[1]);
       void sha384_hash(const unsigned char data[], 
                            unsigned long len, sha384_ctx ctx[1]);
       void sha384_end(unsigned char hval[], sha384_ctx ctx[1]);

       void sha512_begin(sha512_ctx ctx[1]);
       void sha512_hash(const unsigned char data[], 
                            unsigned long len, sha512_ctx ctx[1]);
       void sha512_end(unsigned char hval[], sha512_ctx ctx[1]);

 In addition there is a function sha2 that can be used to call all these
 functions using a call with a hash length parameter as follows:

       int sha2_begin(unsigned long len, sha2_ctx ctx[1]);
       void sha2_hash(const unsigned char data[], 
                            unsigned long len, sha2_ctx ctx[1]);
       void sha2_end(unsigned char hval[], sha2_ctx ctx[1]);

 My thanks to Erik Andersen <[e-mail]> for testing this code 
 on big-endian systems and for his assistance with corrections
*/

/* define the hash functions that you need          */

#define SHA_2           /* for dynamic hash length  */
#define SHA_256
#define SHA_384
#define SHA_512

#include <string.h>     /* for memcpy() etc.        */
#include <stdlib.h>     /* for _lrotr with VC++     */

#include "sha2.h"

/*  1. PLATFORM SPECIFIC INCLUDES */

#if defined(__GNU_LIBRARY__)
#  include <byteswap.h>
#  include <endian.h>
#elif defined(__CRYPTLIB__)
#  if defined( INC_ALL )
#    include "crypt.h"
#  elif defined( INC_CHILD )
#    include "../crypt.h"
#  else
#    include "crypt.h"
#  endif
#  if defined(DATA_LITTLEENDIAN)
#    define PLATFORM_BYTE_ORDER SHA_LITTLE_ENDIAN
#  else
#    define PLATFORM_BYTE_ORDER SHA_BIG_ENDIAN
#  endif
#elif defined(_MSC_VER)
#  include <stdlib.h>
#elif !defined(WIN32)
#  include <stdlib.h>
#  if !defined (_ENDIAN_H)
#    include <sys/param.h>
#  else
#    include _ENDIAN_H
#  endif
#endif

/*  2. BYTE ORDER IN 32-BIT WORDS

    To obtain the highest speed on processors with 32-bit words, this code 
    needs to determine the order in which bytes are packed into such words.
    The following block of code is an attempt to capture the most obvious 
    ways in which various environemnts specify their endian definitions. 
    It may well fail, in which case the definitions will need to be set by 
    editing at the points marked **** EDIT HERE IF NECESSARY **** below.
*/
#define SHA_LITTLE_ENDIAN   1234 /* byte 0 is least significant (i386) */
#define SHA_BIG_ENDIAN      4321 /* byte 0 is most significant (mc68k) */

#if !defined(PLATFORM_BYTE_ORDER)
#if defined(LITTLE_ENDIAN) || defined(BIG_ENDIAN)
#  if defined(LITTLE_ENDIAN) && defined(BIG_ENDIAN)
#    if defined(BYTE_ORDER)
#      if   (BYTE_ORDER == LITTLE_ENDIAN)
#        define PLATFORM_BYTE_ORDER SHA_LITTLE_ENDIAN
#      elif (BYTE_ORDER == BIG_ENDIAN)
#        define PLATFORM_BYTE_ORDER SHA_BIG_ENDIAN
#      endif
#    endif
#  elif defined(LITTLE_ENDIAN) && !defined(BIG_ENDIAN) 
#    define PLATFORM_BYTE_ORDER SHA_LITTLE_ENDIAN
#  elif !defined(LITTLE_ENDIAN) && defined(BIG_ENDIAN)
#    define PLATFORM_BYTE_ORDER SHA_BIG_ENDIAN
#  endif
#elif defined(_LITTLE_ENDIAN) || defined(_BIG_ENDIAN)
#  if defined(_LITTLE_ENDIAN) && defined(_BIG_ENDIAN)
#    if defined(_BYTE_ORDER)
#      if   (_BYTE_ORDER == _LITTLE_ENDIAN)
#        define PLATFORM_BYTE_ORDER SHA_LITTLE_ENDIAN
#      elif (_BYTE_ORDER == _BIG_ENDIAN)
#        define PLATFORM_BYTE_ORDER SHA_BIG_ENDIAN
#      endif
#    endif
#  elif defined(_LITTLE_ENDIAN) && !defined(_BIG_ENDIAN) 
#    define PLATFORM_BYTE_ORDER SHA_LITTLE_ENDIAN
#  elif !defined(_LITTLE_ENDIAN) && defined(_BIG_ENDIAN)
#    define PLATFORM_BYTE_ORDER SHA_BIG_ENDIAN
#  endif
#elif 0     /* **** EDIT HERE IF NECESSARY **** */
#define PLATFORM_BYTE_ORDER SHA_LITTLE_ENDIAN
#elif 0     /* **** EDIT HERE IF NECESSARY **** */
#define PLATFORM_BYTE_ORDER SHA_BIG_ENDIAN
#elif (('1234' >> 24) == '1')
#  define PLATFORM_BYTE_ORDER SHA_LITTLE_ENDIAN
#elif (('4321' >> 24) == '1')
#  define PLATFORM_BYTE_ORDER SHA_BIG_ENDIAN
#endif
#endif

#if !defined(PLATFORM_BYTE_ORDER)
#  error Please set undetermined byte order (lines 159 or 161 of sha2.c).
#endif

#ifdef _MSC_VER
#pragma intrinsic(memcpy)
#endif

#define rotr32(x,n)   (((x) >> n) | ((x) << (32 - n)))

#if !defined(bswap_32)
#define bswap_32(x) (rotr32((x), 24) & 0x00ff00ff | rotr32((x), 8) & 0xff00ff00)
#endif

#if (PLATFORM_BYTE_ORDER == SHA_LITTLE_ENDIAN)
#define SWAP_BYTES
#else
#undef  SWAP_BYTES
#endif

#if defined(SHA_2) || defined(SHA_256)

#define SHA256_MASK (SHA256_BLOCK_SIZE - 1)

#if defined(SWAP_BYTES)
#define	bsw_32(p,n)	{ int _i = (n);	while(_i--) p[_i] = bswap_32(p[_i]); }
#else
#define	bsw_32(p,n)	
#endif

/* SHA256 mixing function definitions   */

#define ch(x,y,z)   (((x) & (y)) ^ (~(x) & (z)))
#define maj(x,y,z)  (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))

#define s256_0(x) (rotr32((x),  2) ^ rotr32((x), 13) ^ rotr32((x), 22)) 
#define s256_1(x) (rotr32((x),  6) ^ rotr32((x), 11) ^ rotr32((x), 25)) 
#define g256_0(x) (rotr32((x),  7) ^ rotr32((x), 18) ^ ((x) >>  3)) 
#define g256_1(x) (rotr32((x), 17) ^ rotr32((x), 19) ^ ((x) >> 10)) 

/* rotated SHA256 round definition. Rather than swapping variables as in    */
/* FIPS-180, different variables are 'rotated' on each round, returning     */
/* to their starting positions every eight rounds                           */

#define h2(i) ctx->wbuf[i & 15] += \
    g256_1(ctx->wbuf[(i + 14) & 15]) + ctx->wbuf[(i + 9) & 15] + g256_0(ctx->wbuf[(i + 1) & 15])

#define h2_cycle(i,j)  \
    v[(7 - i) & 7] += (j ? h2(i) : ctx->wbuf[i & 15]) + k256[i + j] \
        + s256_1(v[(4 - i) & 7]) + ch(v[(4 - i) & 7], v[(5 - i) & 7], v[(6 - i) & 7]); \
    v[(3 - i) & 7] += v[(7 - i) & 7]; \
    v[(7 - i) & 7] += s256_0(v[(0 - i) & 7]) + maj(v[(0 - i) & 7], v[(1 - i) & 7], v[(2 - i) & 7])

/* SHA256 mixing data   */

const sha2_32t k256[64] =
{   n_u32(428a2f98), n_u32(71374491), n_u32(b5c0fbcf), n_u32(e9b5dba5), 
    n_u32(3956c25b), n_u32(59f111f1), n_u32(923f82a4), n_u32(ab1c5ed5), 
    n_u32(d807aa98), n_u32(12835b01), n_u32(243185be), n_u32(550c7dc3), 
    n_u32(72be5d74), n_u32(80deb1fe), n_u32(9bdc06a7), n_u32(c19bf174), 
    n_u32(e49b69c1), n_u32(efbe4786), n_u32(0fc19dc6), n_u32(240ca1cc), 
    n_u32(2de92c6f), n_u32(4a7484aa), n_u32(5cb0a9dc), n_u32(76f988da), 
    n_u32(983e5152), n_u32(a831c66d), n_u32(b00327c8), n_u32(bf597fc7), 
    n_u32(c6e00bf3), n_u32(d5a79147), n_u32(06ca6351), n_u32(14292967), 
    n_u32(27b70a85), n_u32(2e1b2138), n_u32(4d2c6dfc), n_u32(53380d13), 
    n_u32(650a7354), n_u32(766a0abb), n_u32(81c2c92e), n_u32(92722c85),
    n_u32(a2bfe8a1), n_u32(a81a664b), n_u32(c24b8b70), n_u32(c76c51a3), 
    n_u32(d192e819), n_u32(d6990624), n_u32(f40e3585), n_u32(106aa070), 
    n_u32(19a4c116), n_u32(1e376c08), n_u32(2748774c), n_u32(34b0bcb5), 
    n_u32(391c0cb3), n_u32(4ed8aa4a), n_u32(5b9cca4f), n_u32(682e6ff3), 
    n_u32(748f82ee), n_u32(78a5636f), n_u32(84c87814), n_u32(8cc70208), 
    n_u32(90befffa), n_u32(a4506ceb), n_u32(bef9a3f7), n_u32(c67178f2),
};

/* SHA256 initialisation data */

const sha2_32t i256[8] =
{
    n_u32(6a09e667), n_u32(bb67ae85), n_u32(3c6ef372), n_u32(a54ff53a),
    n_u32(510e527f), n_u32(9b05688c), n_u32(1f83d9ab), n_u32(5be0cd19)
};

void sha256_begin(sha256_ctx ctx[1])
{
    ctx->count[0] = ctx->count[1] = 0;
    memcpy(ctx->hash, i256, 8 * sizeof(sha2_32t));
}

/* Compile 64 bytes of hash data into SHA256 digest value   */
/* NOTE: this routine assumes that the byte order in the    */
/* ctx->wbuf[] at this point is in such an order that low   */
/* address bytes in the ORIGINAL byte stream placed in this */
/* buffer will now go to the high end of words on BOTH big  */
/* and little endian systems                                */

void sha256_compile(sha256_ctx ctx[1])
{   sha2_32t	v[8], j;

    memcpy(v, ctx->hash, 8 * sizeof(sha2_32t));

    for(j = 0; j < 64; j += 16)
    {
        h2_cycle( 0, j); h2_cycle( 1, j); h2_cycle( 2, j); h2_cycle( 3, j);
        h2_cycle( 4, j); h2_cycle( 5, j); h2_cycle( 6, j); h2_cycle( 7, j);
        h2_cycle( 8, j); h2_cycle( 9, j); h2_cycle(10, j); h2_cycle(11, j);
        h2_cycle(12, j); h2_cycle(13, j); h2_cycle(14, j); h2_cycle(15, j);
    }

    ctx->hash[0] += v[0]; ctx->hash[1] += v[1]; ctx->hash[2] += v[2]; ctx->hash[3] += v[3];
    ctx->hash[4] += v[4]; ctx->hash[5] += v[5]; ctx->hash[6] += v[6]; ctx->hash[7] += v[7];
}

/* SHA256 hash data in an array of bytes into hash buffer   */
/* and call the hash_compile function as required.          */

void sha256_hash(const unsigned char data[], unsigned long len, sha256_ctx ctx[1])
{   sha2_32t pos = (sha2_32t)(ctx->count[0] & SHA256_MASK), 
             space = SHA256_BLOCK_SIZE - pos;
    const unsigned char *sp = data;

    if((ctx->count[0] += len) < len)
        ++(ctx->count[1]);

    while(len >= space)     /* tranfer whole blocks while possible  */
    {
        memcpy(((unsigned char*)ctx->wbuf) + pos, sp, space);
        sp += space; len -= space; space = SHA256_BLOCK_SIZE; pos = 0; 
		bsw_32(ctx->wbuf, SHA256_BLOCK_SIZE >> 2)
        sha256_compile(ctx);
    }

    memcpy(((unsigned char*)ctx->wbuf) + pos, sp, len);
}

/* SHA256 Final padding and digest calculation  */

static sha2_32t  m1[4] =
{
    n_u32(00000000), n_u32(ff000000), n_u32(ffff0000), n_u32(ffffff00)
};

static sha2_32t  b1[4] =
{
    n_u32(80000000), n_u32(00800000), n_u32(00008000), n_u32(00000080)
};

void sha256_end(unsigned char hval[], sha256_ctx ctx[1])
{   sha2_32t    i = (sha2_32t)(ctx->count[0] & SHA256_MASK);

	bsw_32(ctx->wbuf, (i + 3) >> 2)
    /* bytes in the buffer are now in an order in which references  */
    /* to 32-bit words will put bytes with lower addresses into the */
    /* top of 32 bit words on BOTH big and little endian machines   */
    
    /* we now need to mask valid bytes and add the padding which is */
    /* a single 1 bit and as many zero bits as necessary.           */
    ctx->wbuf[i >> 2] = (ctx->wbuf[i >> 2] & m1[i & 3]) | b1[i & 3];

    /* we need 9 or more empty positions, one for the padding byte  */
    /* (above) and eight for the length count.  If there is not     */
    /* enough space pad and empty the buffer                        */
    if(i > SHA256_BLOCK_SIZE - 9)
    {
        if(i < 60) ctx->wbuf[15] = 0;
        sha256_compile(ctx);
        i = 0;
    }
    else    /* compute a word index for the empty buffer positions  */
        i = (i >> 2) + 1;

    while(i < 14) /* and zero pad all but last two positions      */ 
        ctx->wbuf[i++] = 0;