text: /*
   *  sha1.c
   *
   *  Copyright (C) 1998, 2009
   *  Paul E. Jones <paulej@packetizer.com>
   *  All Rights Reserved
   *
   *****************************************************************************
   *  $Id: sha1.c 12 2009-06-22 19:34:25Z paulej $
   *****************************************************************************
   *
   *  Description:
   *      This file implements the Secure Hashing Standard as defined
   *      in FIPS PUB 180-1 published April 17, 1995.
   *
   *      The Secure Hashing Standard, which uses the Secure Hashing
   *      Algorithm (SHA), produces a 160-bit message digest for a
   *      given data stream.  In theory, it is highly improbable that
   *      two messages will produce the same message digest.  Therefore,
   *      this algorithm can serve as a means of providing a "fingerprint"
   *      for a message.
   *
   *  Portability Issues:
   *      SHA-1 is defined in terms of 32-bit "words".  This code was
   *      written with the expectation that the processor has at least
   *      a 32-bit machine word size.  If the machine word size is larger,
   *      the code should still function properly.  One caveat to that
   *      is that the input functions taking characters and character
   *      arrays assume that only 8 bits of information are stored in each
   *      character.
   *
   *  Caveats:
   *      SHA-1 is designed to work with messages less than 2^64 bits
   *      long. Although SHA-1 allows a message digest to be generated for
   *      messages of any number of bits less than 2^64, this
   *      implementation only works with messages with a length that is a
   *      multiple of the size of an 8-bit character.
   *
   */
  
  #include "include/sha1.h"
  
  /*
   *  Define the circular shift macro
   */
  #define SHA1CircularShift(bits,word) \
                  ((((word) << (bits)) & 0xFFFFFFFF) | \
                  ((word) >> (32-(bits))))
  
  /* Function prototypes */
  void SHA1ProcessMessageBlock(SHA1Context *);
  void SHA1PadMessage(SHA1Context *);
  
  /*
   *  SHA1Reset
   *
   *  Description:
   *      This function will initialize the SHA1Context in preparation
   *      for computing a new message digest.
   *
   *  Parameters:
   *      context: [in/out]
   *          The context to reset.
   *
   *  Returns:
   *      Nothing.
   *
   *  Comments:
   *
   */
  void SHA1Reset(SHA1Context *context)
  {
      context->Length_Low             = 0;
      context->Length_High            = 0;
      context->Message_Block_Index    = 0;
  
      context->Message_Digest[0]      = 0x67452301;
      context->Message_Digest[1]      = 0xEFCDAB89;
      context->Message_Digest[2]      = 0x98BADCFE;
      context->Message_Digest[3]      = 0x10325476;
      context->Message_Digest[4]      = 0xC3D2E1F0;
  
      context->Computed   = 0;
      context->Corrupted  = 0;
  }
  
  /*
   *  SHA1Result
   *
   *  Description:
   *      This function will return the 160-bit message digest into the
   *      Message_Digest array within the SHA1Context provided
   *
   *  Parameters:
   *      context: [in/out]
   *          The context to use to calculate the SHA-1 hash.
   *
   *  Returns:
   *      1 if successful, 0 if it failed.
   *
   *  Comments:
   *
   */
  int SHA1Result(SHA1Context *context)
  {
  
      if (context->Corrupted)
      {
          return 0;
      }
  
      if (!context->Computed)
      {
          SHA1PadMessage(context);
          context->Computed = 1;
      }
  
      return 1;
  }
  
  /*
   *  SHA1Input
   *
   *  Description:
   *      This function accepts an array of octets as the next portion of
   *      the message.
   *
   *  Parameters:
   *      context: [in/out]
   *          The SHA-1 context to update
   *      message_array: [in]
   *          An array of characters representing the next portion of the
   *          message.
   *      length: [in]
   *          The length of the message in message_array
   *
   *  Returns:
   *      Nothing.
   *
   *  Comments:
   *
   */
  void SHA1Input(     SHA1Context         *context,
                      const unsigned char *message_array,
                      unsigned            length)
  {
      if (!length)
      {
          return;
      }
  
      if (context->Computed || context->Corrupted)
      {
          context->Corrupted = 1;
          return;
      }
  
      while(length-- && !context->Corrupted)
      {
          context->Message_Block[context->Message_Block_Index++] =
                                                  (*message_array & 0xFF);
  
          context->Length_Low += 8;
          /* Force it to 32 bits */
          context->Length_Low &= 0xFFFFFFFF;
          if (context->Length_Low == 0)
          {
              context->Length_High++;
              /* Force it to 32 bits */
              context->Length_High &= 0xFFFFFFFF;
              if (context->Length_High == 0)
              {
                  /* Message is too long */
                  context->Corrupted = 1;
              }
          }
  
          if (context->Message_Block_Index == 64)
          {
              SHA1ProcessMessageBlock(context);
          }
  
          message_array++;
      }
  }
  
  /*
   *  SHA1ProcessMessageBlock
   *
   *  Description:
   *      This function will process the next 512 bits of the message
   *      stored in the Message_Block array.
   *
   *  Parameters:
   *      None.
   *
   *  Returns:
   *      Nothing.
   *
   *  Comments:
   *      Many of the variable names in the SHAContext, especially the
   *      single character names, were used because those were the names
   *      used in the publication.
   *
   *
   */
  void SHA1ProcessMessageBlock(SHA1Context *context)
  {
      const unsigned K[] =            /* Constants defined in SHA-1   */
      {
          0x5A827999,
          0x6ED9EBA1,
          0x8F1BBCDC,
          0xCA62C1D6
      };
      int         t;                  /* Loop counter                 */
      unsigned    temp;               /* Temporary word value         */
      unsigned    W[80];              /* Word sequence                */
      unsigned    A, B, C, D, E;      /* Word buffers                 */
  
      /*
       *  Initialize the first 16 words in the array W
       */
      for(t = 0; t < 16; t++)
      {
          W[t] = ((unsigned) context->Message_Block[t * 4]) << 24;
          W[t] |= ((unsigned) context->Message_Block[t * 4 + 1]) << 16;
          W[t] |= ((unsigned) context->Message_Block[t * 4 + 2]) << 8;
          W[t] |= ((unsigned) context->Message_Block[t * 4 + 3]);
      }
  
      for(t = 16; t < 80; t++)
      {
         W[t] = SHA1CircularShift(1,W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16]);
      }
  
      A = context->Message_Digest[0];
      B = context->Message_Digest[1];
      C = context->Message_Digest[2];
      D = context->Message_Digest[3];
      E = context->Message_Digest[4];
  
      for(t = 0; t < 20; t++)
      {
          temp =  SHA1CircularShift(5,A) +
                  ((B & C) | ((~B) & D)) + E + W[t] + K[0];
          temp &= 0xFFFFFFFF;
          E = D;
          D = C;
          C = SHA1CircularShift(30,B);
          B = A;
          A = temp;
      }
  
      for(t = 20; t < 40; t++)
      {
          temp = SHA1CircularShift(5,A) + (B ^ C ^ D) + E + W[t] + K[1];
          temp &= 0xFFFFFFFF;
          E = D;
          D = C;
          C = SHA1CircularShift(30,B);
          B = A;
          A = temp;
      }
  
      for(t = 40; t < 60; t++)
      {
          temp = SHA1CircularShift(5,A) +
                 ((B & C) | (B & D) | (C & D)) + E + W[t] + K[2];
          temp &= 0xFFFFFFFF;
          E = D;
          D = C;
          C = SHA1CircularShift(30,B);
          B = A;
          A = temp;
      }
  
      for(t = 60; t < 80; t++)
      {
          temp = SHA1CircularShift(5,A) + (B ^ C ^ D) + E + W[t] + K[3];
          temp &= 0xFFFFFFFF;
          E = D;
          D = C;
          C = SHA1CircularShift(30,B);
          B = A;
          A = temp;
      }
  
      context->Message_Digest[0] =
                          (context->Message_Digest[0] + A) & 0xFFFFFFFF;
      context->Message_Digest[1] =
                          (context->Message_Digest[1] + B) & 0xFFFFFFFF;
      context->Message_Digest[2] =
                          (context->Message_Digest[2] + C) & 0xFFFFFFFF;
      context->Message_Digest[3] =
                          (context->Message_Digest[3] + D) & 0xFFFFFFFF;
      context->Message_Digest[4] =
                          (context->Message_Digest[4] + E) & 0xFFFFFFFF;
  
      context->Message_Block_Index = 0;
  }
  
  /*
   *  SHA1PadMessage
   *
   *  Description:
   *      According to the standard, the message must be padded to an even
   *      512 bits.  The first padding bit must be a '1'.  The last 64
   *      bits represent the length of the original message.  All bits in
   *      between should be 0.  This function will pad the message
   *      according to those rules by filling the Message_Block array
   *      accordingly.  It will also call SHA1ProcessMessageBlock()
   *      appropriately.  When it returns, it can be assumed that the
   *      message digest has been computed.
   *
   *  Parameters:
   *      context: [in/out]
   *          The context to pad
   *
   *  Returns:
   *      Nothing.
   *
   *  Comments:
   *
   */
  void SHA1PadMessage(SHA1Context *context)
  {
      /*
       *  Check to see if the current message block is too small to hold
       *  the initial padding bits and length.  If so, we will pad the
       *  block, process it, and then continue padding into a second
       *  block.
       */
      if (context->Message_Block_Index > 55)
      {
          context->Message_Block[context->Message_Block_Index++] = 0x80;
          while(context->Message_Block_Index < 64)
          {
              context->Message_Block[context->Message_Block_Index++] = 0;
          }
  
          SHA1ProcessMessageBlock(context);
  
          while(context->Message_Block_Index < 56)
          {
              context->Message_Block[context->Message_Block_Index++] = 0;
          }
      }
      else
      {
          context->Message_Block[context->Message_Block_Index++] = 0x80;
          while(context->Message_Block_Index < 56)
          {
              context->Message_Block[context->Message_Block_Index++] = 0;
          }
      }
  
      /*
       *  Store the message length as the last 8 octets
       */
      context->Message_Block[56] = (context->Length_High >> 24) & 0xFF;
      context->Message_Block[57] = (context->Length_High >> 16) & 0xFF;
      context->Message_Block[58] = (context->Length_High >> 8) & 0xFF;
      context->Message_Block[59] = (context->Length_High) & 0xFF;
      context->Message_Block[60] = (context->Length_Low >> 24) & 0xFF;
      context->Message_Block[61] = (context->Length_Low >> 16) & 0xFF;
      context->Message_Block[62] = (context->Length_Low >> 8) & 0xFF;
      context->Message_Block[63] = (context->Length_Low) & 0xFF;
  
      SHA1ProcessMessageBlock(context);
  }
  