/*
 *  sha1.h
 *
 *  Copyright (C) 1998, 2009
 *  Paul E. Jones <paulej@packetizer.com>
 *  All Rights Reserved
 *
 *****************************************************************************
 *  $Id: sha1.h 12 2009-06-22 19:34:25Z paulej $
 *****************************************************************************
 *
 *  Description:
 *      This class implements the Secure Hashing Standard as defined
 *      in FIPS PUB 180-1 published April 17, 1995.
 *
 *      Many of the variable names in the SHA1Context, especially the
 *      single character names, were used because those were the names
 *      used in the publication.
 *
 *      Please read the file sha1.c for more information.
 *
 */

#include <stdio.h>
#include <string.h>
#ifdef WIN32
#include <io.h>
#endif
#include <fcntl.h>
#include <string/stdstring.h>

#ifndef _SHA1_H_
#define _SHA1_H_

/* 
 *  This structure will hold context information for the hashing
 *  operation
 */
typedef struct SHA1Context
{
   unsigned Message_Digest[5]; /* Message Digest (output)          */

   unsigned Length_Low;        /* Message length in bits           */
   unsigned Length_High;       /* Message length in bits           */

   unsigned char Message_Block[64]; /* 512-bit message blocks      */
   int Message_Block_Index;    /* Index into message block array   */

   int Computed;               /* Is the digest computed?          */
   int Corrupted;              /* Is the message digest corruped?  */
} SHA1Context;

/*
 *  Function Prototypes
 */
void SHA1Reset(SHA1Context *);
int SHA1Result(SHA1Context *);
void SHA1Input( SHA1Context *,
      const unsigned char *,
      unsigned);

#endif

/*
 *  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 "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);
}