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md5的实现

Posted on 2010-10-09 16:44 Prayer 阅读(602) 评论(0)  编辑 收藏 引用 所属分类: 算法
 具体的一个MD5实现
  /*
  * md5 -- compute and check MD5 message digest.
  * this version only can calculate the char string.
  *
  * MD5 (Message-Digest algorithm 5) is a widely used, partially
  * insecure cryptographic hash function with a 128-bit hash value.
  *
  * Author: redraiment
  * Date: Aug 27, 2008
  * Version: 0.1.6
  */
  #include <stdlib.h>
  #include <string.h>
  #include <stdio.h>
  #include <math.h>
  #define SINGLE_ONE_BIT 0x80
  #define BLOCK_SIZE 512
  #define MOD_SIZE 448
  #define APP_SIZE 64
  #define BITS 8
  // MD5 Chaining Variable
  #define A 0x67452301UL
  #define B 0xEFCDAB89UL
  #define C 0x98BADCFEUL
  #define D 0x10325476UL
  // Creating own types
  #ifdef UINT64
  # undef UINT64
  #endif
  #ifdef UINT32
  # undef UINT32
  #endif
  typedef unsigned long long UINT64;
  typedef unsigned long UINT32;
  typedef unsigned char UINT8;
  typedef struct
  {
  char * message;
  UINT64 length;
  }STRING;
  const UINT32 X[4][2] = {{0, 1}, {1, 5}, {5, 3}, {0, 7}};
  // Constants for MD5 transform routine.
  const UINT32 S[4][4] = {
  { 7, 12, 17, 22 },
  { 5, 9, 14, 20 },
  { 4, 11, 16, 23 },
  { 6, 10, 15, 21 }
  };
  // F, G, H and I are basic MD5 functions.
  UINT32 F( UINT32 X, UINT32 Y, UINT32 Z )
  {
  return ( X & Y ) | ( ~X & Z );
  }
  UINT32 G( UINT32 X, UINT32 Y, UINT32 Z )
  {
  return ( X & Z ) | ( Y & ~Z );
  }
  UINT32 H( UINT32 X, UINT32 Y, UINT32 Z )
  {
  return X ^ Y ^ Z;
  }
  UINT32 I( UINT32 X, UINT32 Y, UINT32 Z )
  {
  return Y ^ ( X | ~Z );
  }
  // rotates x left s bits.
  UINT32 rotate_left( UINT32 x, UINT32 s )
  {
  return ( x << s ) | ( x >> ( 32 - s ) );
  }
  // Pre-processin
  UINT32 count_padding_bits ( UINT32 length )
  {
  UINT32 div = length * BITS / BLOCK_SIZE;
  UINT32 mod = length * BITS % BLOCK_SIZE;
  UINT32 c_bits;
  if ( mod == 0 )
  c_bits = MOD_SIZE;
  else
  c_bits = ( MOD_SIZE + BLOCK_SIZE - mod ) % BLOCK_SIZE;
  return c_bits / BITS;
  }
  STRING append_padding_bits ( char * argv )
  {
  UINT32 msg_length = strlen ( argv );
  UINT32 bit_length = count_padding_bits ( msg_length );
  UINT64 app_length = msg_length * BITS;
  STRING string;
  string.message = (char *)malloc(msg_length + bit_length + APP_SIZE / BITS);
  // Save message
  strncpy ( string.message, argv, msg_length );
  // Pad out to mod 64.
  memset ( string.message + msg_length, 0, bit_length );
  string.message [ msg_length ] = SINGLE_ONE_BIT;
  // Append length (before padding).
  memmove ( string.message + msg_length + bit_length, (char *)&app_length, sizeof( UINT64 ) );
  string.length = msg_length + bit_length + sizeof( UINT64 );
  return string;
  }
  int main ( int argc, char *argv[] )
  {
  STRING string;
  UINT32 w[16];
  UINT32 chain[4];
  UINT32 state[4];
  UINT8 r[16];
  UINT32 ( *auxi[ 4 ])( UINT32, UINT32, UINT32 ) = { F, G, H, I };
  int roundIdx;
  int argIdx;
  int sIdx;
  int wIdx;
  int i;
  int j;
  if ( argc < 2 )
  {
  fprintf ( stderr, "usage: %s string ...\n", argv[ 0 ] );
  return EXIT_FAILURE;
  }
  for ( argIdx = 1; argIdx < argc; argIdx++ )
  {
  string = append_padding_bits ( argv[ argIdx ] );
  // MD5 initialization.
  chain[0] = A;
  chain[1] = B;
  chain[2] = C;
  chain[3] = D;
  for ( j = 0; j < string.length; j += BLOCK_SIZE / BITS)
  {
  memmove ( (char *)w, string.message + j, BLOCK_SIZE / BITS );
  memmove ( state, chain, sizeof(chain) );
  for ( roundIdx = 0; roundIdx < 4; roundIdx++ )
  {
  wIdx = X[ roundIdx ][ 0 ];
  sIdx = 0;
  for ( i = 0; i < 16; i++ )
  {
  // FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
  // Rotation is separate from addition to prevent recomputation.
  state[sIdx] = state [ (sIdx + 1) % 4 ] +
  rotate_left ( state[sIdx] +
  ( *auxi[ roundIdx ] )
  ( state[(sIdx+1) % 4], state[(sIdx+2) % 4], state[(sIdx+3) % 4]) +
  w[ wIdx ] +
  (UINT32)floor( (1ULL << 32) * fabs(sin( roundIdx * 16 + i + 1 )) ),
  S[ roundIdx ][ i % 4 ]);
  sIdx = ( sIdx + 3 ) % 4;
  wIdx = ( wIdx + X[ roundIdx ][ 1 ] ) & 0xF;
  }
  }
  chain[ 0 ] += state[ 0 ];
  chain[ 1 ] += state[ 1 ];
  chain[ 2 ] += state[ 2 ];
  chain[ 3 ] += state[ 3 ];
  }
  memmove ( r + 0, (char *)&chain[0], sizeof(UINT32) );
  memmove ( r + 4, (char *)&chain[1], sizeof(UINT32) );
  memmove ( r + 8, (char *)&chain[2], sizeof(UINT32) );
  memmove ( r + 12, (char *)&chain[3], sizeof(UINT32) );
  for ( i = 0; i < 16; i++ )
  printf ( "%02x", r[i] );
  putchar ( '\n' );
  }
  return EXIT_SUCCESS;
  }
  /* 以上程序可以在任意一款支持ANSI C的编译器上编译通过 */

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