scirfmmon/source/sha1.c

//$Header: /home/dashley/cvsrep/e3ft_gpl01/e3ft_gpl01/winprojs/scirfmmon/source/sha1.c,v 1.2 2008/12/15 21:10:08 dashley Exp $
//--------------------------------------------------------------------------------
//Copyright 2008 David T. Ashley
//-------------------------------------------------------------------------------------------------
//This source code and any program in which it is compiled/used is provided under the GNU GENERAL
//PUBLIC LICENSE, Version 3, full license text below.
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//    but WITHOUT ANY WARRANTY; without even the implied warranty of
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//-------------------------------------------------------------------------------------------------
//--------------------------------------------------------------------------------
//This file is part of scirfmmon.
//
//scirfmmon is free software: you can redistribute it and/or modify
//it under the terms of the GNU General Public License as published by
//the Free Software Foundation, either version 3 of the License, or
//(at your option) any later version.
//
//scirfmmon is distributed in the hope that it will be useful,
//but WITHOUT ANY WARRANTY; without even the implied warranty of
//MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//GNU General Public License for more details.
//
//You should have received a copy of the GNU General Public License
//along with scirfmmon (see the file copying.txt).  If not, 
//see <http://www.gnu.org/licenses/>.
//--------------------------------------------------------------------------------
//A description of the functionality of this module and the public interface
//definition is contained in the associated .H file.
//
#define MODULE_SHA1

#include <assert.h>
#include <stddef.h>
#include <stdio.h>
#include <string.h>

#include "sha1.h"

#include "charfunc.h"


//This is a left rotation macro, for efficiency.  This
//macro rotates a 32-bit quantity x left (cyclically) by 
//n bits.
#define SHA1_FUNC_ROT_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))


//This is the padding table to append.  It is done with
//an array for quickness in block operations.  This 
//comes from the requirement of the algorithm that after 
//the message, a '1' be appended.  This is a '1' then 
//511 bits of '0'.
//
static unsigned char SHA1_pad_table[] =
   { 
   0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
   };


void SHA1_Sha1StateStructOpen(struct SHA1_Sha1StateStruct *arg)
   {
   assert(arg != NULL);

   memset(arg, 0, sizeof(struct SHA1_Sha1StateStruct));
      //Everything to zero, processed bitcount automatically set to zero.

   arg->A = 0x67452301;  //H0 in the RFC.
   arg->B = 0xEFCDAB89;  //H1 in the RFC.
   arg->C = 0x98BADCFE;  //H2 in the RFC.
   arg->D = 0x10325476;  //H3 in the RFC.
   arg->E = 0xC3D2E1F0;  //H4 in the RFC.
   }


//Copies the byte buffer to the word buffer within the state block.
//This is done in a way which hides big-endian/little-endian concerns.
//The byte buffer is more convenient for handling incoming data,
//but the word buffer is more convenient for performing the algorithm
//according to the RFC.
//
static void SHA1_CopyBytesToWords(struct SHA1_Sha1StateStruct *arg)
   {
   int i;

   assert(arg != NULL);

   //Copy the buffer contents into the words.  We need to be careful
   //to do this right, because of big-endian/little-endian concerns.
   //
   //Note that since buf[0] is filled first, it goes on the left.
   //MSB is earlier in array.
   //
   for (i=0; i<16; i++)
      {
      assert((i * 4 + 3) < 64);
      arg->X[i] = (((unsigned int)(arg->buf[i*4+0])) << 24)
                  +
                  (((unsigned int)(arg->buf[i*4+1])) << 16)
                  +
                  (((unsigned int)(arg->buf[i*4+2])) <<  8)
                  +
                  (((unsigned int)(arg->buf[i*4+3]))   );
      }
   }


//Does the Sha1 rounds as specified by RFC 3174.
//
static void SHA1_DoSha1Rounds(struct SHA1_Sha1StateStruct *arg)
   {
   uint32_t A, B, C, D, E;
         //We also want to buffer out the state variables, to eliminate
         //the risk of repeated pointer dereferences.
   unsigned X[16];
         //Buffer to avoid repeated dereferences.

   const uint32_t K[] 
      = 
      {
      0x5A827999,
      0x6ED9EBA1,
      0x8F1BBCDC,
      0xCA62C1D6
      };

   int           t;                 /* Loop counter                */
   uint32_t      temp;              /* Temporary word value        */
   uint32_t      W[80];             /* Word sequence               */

   //int i =0;

   assert(arg != NULL);

   //Copy bytes into words.
   SHA1_CopyBytesToWords(arg);

   //Copy out the buffer for speed.
   X[ 0] = arg->X[ 0];
   X[ 1] = arg->X[ 1];
   X[ 2] = arg->X[ 2];
   X[ 3] = arg->X[ 3];
   X[ 4] = arg->X[ 4];
   X[ 5] = arg->X[ 5];
   X[ 6] = arg->X[ 6];
   X[ 7] = arg->X[ 7];
   X[ 8] = arg->X[ 8];
   X[ 9] = arg->X[ 9];
   X[10] = arg->X[10];
   X[11] = arg->X[11];
   X[12] = arg->X[12];
   X[13] = arg->X[13];
   X[14] = arg->X[14];
   X[15] = arg->X[15];

   //Buffer out the state for speed.
   A = arg->A;
   B = arg->B;
   C = arg->C;
   D = arg->D;
   E = arg->E;


#if 0
   printf("------------------\n");
   printf("Just after par copy.\n");
   printf("A : %08X.\n", A);
   printf("B : %08X.\n", B);
   printf("C : %08X.\n", C);
   printf("D : %08X.\n", D);
   printf("E : %08X.\n", E);
   for (i=0; i<16; i++)
     {
       printf("X[%02d] : %08X.\n", i, X[i]);
     }
   printf("------------------\n");
#endif     

   /* This code comes directly out of RFC 3174.     */  
   /* Initialize the first 16 words in the array W. */
   for(t = 0; t < 16; t++)
      {
      W[t] = X[t];
      }

   for(t = 16; t < 80; t++)
      {
      W[t] = SHA1_FUNC_ROT_LEFT(W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16], 1);
      }

   for(t = 0; t < 20; t++)
      {
      temp = SHA1_FUNC_ROT_LEFT(A,5) + ((B & C) | ((~B) & D)) + E + W[t] + K[0];
      E    = D;
      D    = C;
      C    = SHA1_FUNC_ROT_LEFT(B,30);
      B    = A;
      A    = temp;
      }

   for(t = 20; t < 40; t++)
      {
      temp = SHA1_FUNC_ROT_LEFT(A,5) + (B ^ C ^ D) + E + W[t] + K[1];
      E    = D;
      D    = C;
      C    = SHA1_FUNC_ROT_LEFT(B,30);
      B    = A;
      A    = temp;
      }

   for(t = 40; t < 60; t++)
      {
      temp = SHA1_FUNC_ROT_LEFT(A,5) + ((B & C) | (B & D) | (C & D)) + E + W[t] + K[2];
      E    = D;
      D    = C;
      C    = SHA1_FUNC_ROT_LEFT(B,30);
      B    = A;
      A    = temp;
      }

   for(t = 60; t < 80; t++)
      {
      temp = SHA1_FUNC_ROT_LEFT(A,5) + (B ^ C ^ D) + E + W[t] + K[3];
      E    = D;
      D    = C;
      C    = SHA1_FUNC_ROT_LEFT(B,30);
      B    = A;
      A    = temp;
      }

   //Perform the four additions as mandated by the RFC, and copy the state
   //back to the structure.
   //
   arg->A += A;
   arg->B += B;
   arg->C += C;
   arg->D += D;
   arg->E += E;
   }


void SHA1_Sha1StateStructAddData(struct SHA1_Sha1StateStruct *arg,
                                    void *pointer_in,
                                    size_t  len)
   {
   uint32_t       low_32;
   uint32_t       byte_offset;
   unsigned char *data;

   assert(arg        != NULL);
   assert(pointer_in != NULL);

   data = (unsigned char *)pointer_in;
      //It is easier to do it this way, rather than cast all the time.

   low_32 = (unsigned int)arg->bit_count;
      //Copy off the least significant bits.  Easier to do once.

   byte_offset = low_32 >> 3;
      //This gives our byte offset, up to 500+Mb or so.
      //This wraps modulo 64 (i.e. even if the data item overflows, we should be OK.

   while(len--)
      {
      //We process rounds AFTER a byte is added to the buffer.  So
      //it is always safe to add a byte first.
      arg->buf[byte_offset & 0x3F] = *data;

      //Nothing to do unless this was the final byte of the buffer.
      if ((byte_offset & 0x3F) == 63)
         {
         SHA1_DoSha1Rounds(arg);
         }

      //Increment.
      data++;
      byte_offset++;
      arg->bit_count += 8;
      }
   }


void SHA1_Sha1StateStructClose(struct SHA1_Sha1StateStruct  *state,
                                  struct SHA1_Sha1ResultStruct *result)
   {
   uint32_t       low_32, high_32, high_32_copy, low_32_copy;
   uint32_t       byte_offset;
   uint32_t       buffer_offset;
   unsigned char  length_buf[8];

   assert(state  != NULL);
   assert(result != NULL);

   //Obtain easier-to-use indices.  These provide a snapshot of the
   //length before padding is done.
   low_32        =  (uint32_t)state->bit_count;
   high_32       =  (uint32_t)(state->bit_count >> 32);
   byte_offset   =  low_32 >> 3;
   buffer_offset =  byte_offset & 0x3F;

   //We need to pad the buffer out to 8 bytes short of a multiple,
   //per RFC 3174.  The last 64 bits are reserved for the length.
   SHA1_Sha1StateStructAddData(state, 
                               SHA1_pad_table,
                               (buffer_offset==56) ? (64) : ((56 - buffer_offset) & 0x3F));

   //At this point we are fully prepped to stuff in the length in bits.
   //Prepare the length in a buffer.
   high_32_copy = high_32;
   low_32_copy  = low_32;
   length_buf[0] = (unsigned char)(high_32_copy >> 24); 
   length_buf[1] = (unsigned char)(high_32_copy >> 16);
   length_buf[2] = (unsigned char)(high_32_copy >>  8);
   length_buf[3] = (unsigned char)(high_32_copy);
   length_buf[4] = (unsigned char)(low_32_copy >>  24);
   length_buf[5] = (unsigned char)(low_32_copy >>  16);
   length_buf[6] = (unsigned char)(low_32_copy >>   8);
   length_buf[7] = (unsigned char)(low_32_copy);

   //Tack on the length.  This is guaranteed to generate end up with
   //the last thing being done the compute plus the index being zero.
   //
   SHA1_Sha1StateStructAddData(state, 
                                  length_buf,
                                  8);

   //Be absolutely sure we are rolled over to zero.
   assert((((int)state->bit_count) & 0x1FF) == 0);

   //Zero out the return state, just to be sure it starts in a defined state.
   memset(result, 0, sizeof(struct SHA1_Sha1ResultStruct));

   //Give caller the binary version of the state.
   result->sha1_words[0] = state->A;
   result->sha1_words[1] = state->B;
   result->sha1_words[2] = state->C;
   result->sha1_words[3] = state->D;
   result->sha1_words[4] = state->E;

   //Convert to string for caller.
   CHARFUNC_int_to_lc_hex_rev(state->A, result->sha1_chars +  0);
   CHARFUNC_int_to_lc_hex_rev(state->B, result->sha1_chars +  8);
   CHARFUNC_int_to_lc_hex_rev(state->C, result->sha1_chars + 16);
   CHARFUNC_int_to_lc_hex_rev(state->D, result->sha1_chars + 24);
   CHARFUNC_int_to_lc_hex_rev(state->E, result->sha1_chars + 32);

   //We have to reverse the presentation order of each 32-bit integer.
   //The function used above makes a string in reverse order, so we
   //need to bring it back to forward order.
   //
   {
   int i;
   char temp;

   for (i=0; i<5; i++)
     {
     temp                        = result->sha1_chars[i*8 + 7];
     result->sha1_chars[i*8 + 7] = result->sha1_chars[i*8 + 0];
     result->sha1_chars[i*8 + 0] = temp;

     temp                        = result->sha1_chars[i*8 + 6];
     result->sha1_chars[i*8 + 6] = result->sha1_chars[i*8 + 1];
     result->sha1_chars[i*8 + 1] = temp;

     temp                        = result->sha1_chars[i*8 + 5];
     result->sha1_chars[i*8 + 5] = result->sha1_chars[i*8 + 2];
     result->sha1_chars[i*8 + 2] = temp;

     temp                        = result->sha1_chars[i*8 + 4];
     result->sha1_chars[i*8 + 4] = result->sha1_chars[i*8 + 3];
     result->sha1_chars[i*8 + 3] = temp;

     }
   }

   result->sha1_chars[40] = 0;  //String terminator.

   //Destroy the state, which may contain sensitive information.
   //This idea came from Rivest's sample code.
   memset(state, 0, sizeof(struct SHA1_Sha1StateStruct));
   }


//Returns version control string for file.
//
const char *SHA1_cvcinfo(void)
   {   
   return ("$Header: /home/dashley/cvsrep/e3ft_gpl01/e3ft_gpl01/winprojs/scirfmmon/source/sha1.c,v 1.2 2008/12/15 21:10:08 dashley Exp $");
   }


//Returns version control string for associated .H file.
//
const char *SHA1_hvcinfo(void)
   {   
   return (SHA1_H_VERSION);
   }


//*****************************************************************************
// $Log: sha1.c,v $
// Revision 1.2  2008/12/15 21:10:08  dashley
// GPL license text added to source code and also to program output.
//
// Revision 1.1  2008/12/13 20:20:24  dashley
// Initial checkin.
//*****************************************************************************
// End of $RCSfile: sha1.c,v $.