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Asterisk developer's documentation :: Codename Pineapple

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sha1.c

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/*
 *
 * Based on the RFC 3174
 * 
 * Full Copyright Statement
 *
 *  Copyright (C) The Internet Society (2001).  All Rights Reserved.
 *
 *  This document and translations of it may be copied and furnished to
 *  others, and derivative works that comment on or otherwise explain it
 *  or assist in its implementation may be prepared, copied, published
 *  and distributed, in whole or in part, without restriction of any
 *  kind, provided that the above copyright notice and this paragraph are
 *  included on all such copies and derivative works.  However, this
 *  document itself may not be modified in any way, such as by removing
 *  the copyright notice or references to the Internet Society or other
 *  Internet organizations, except as needed for the purpose of
 *  developing Internet standards in which case the procedures for
 *  copyrights defined in the Internet Standards process must be
 *  followed, or as required to translate it into languages other than
 *  English.
 *
 *  The limited permissions granted above are perpetual and will not be
 *  revoked by the Internet Society or its successors or assigns.

 *  This document and the information contained herein is provided on an
 *  "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
 *  TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
 *  BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
 *  HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
 *  MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
 *
 *
 * 
 *  Description:
 *   This file implements the Secure Hashing Algorithm 1 as
 *   defined in FIPS PUB 180-1 published April 17, 1995.
 *
 *   The SHA-1, produces a 160-bit message digest for a given
 *   data stream.  It should take about 2**n steps to find a
 *   message with the same digest as a given message and
 *   2**(n/2) to find any two messages with the same digest,
 *   when n is the digest size in bits.  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
 *   uses <stdint.h> (included via "sha1.h" to define 32 and 8
 *   bit unsigned integer types.  If your C compiler does not
 *   support 32 bit unsigned integers, this code is not
 *   appropriate.
 *
 *  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 "asterisk/sha1.h"

/*
 *  Define the SHA1 circular left shift macro
 */
#define SHA1CircularShift(bits,word) \
               (((word) << (bits)) | ((word) >> (32-(bits))))

/* Local Function Prototyptes */
void SHA1PadMessage(SHA1Context *);
void SHA1ProcessMessageBlock(SHA1Context *);

/*
 *  SHA1Reset
 *
 *  Description:
 *   This function will initialize the SHA1Context in preparation
 *   for computing a new SHA1 message digest.
 *
 *  Parameters:
 *   context: [in/out]
 *       The context to reset.
 *
 *  Returns:
 *   sha Error Code.
 *
 */
int SHA1Reset(SHA1Context *context)
{
   if (!context) {
      return shaNull;
   }

   context->Length_Low             = 0;
   context->Length_High            = 0;
   context->Message_Block_Index    = 0;

   context->Intermediate_Hash[0]   = 0x67452301;
   context->Intermediate_Hash[1]   = 0xEFCDAB89;
   context->Intermediate_Hash[2]   = 0x98BADCFE;
   context->Intermediate_Hash[3]   = 0x10325476;
   context->Intermediate_Hash[4]   = 0xC3D2E1F0;

   context->Computed               = 0;
   context->Corrupted              = 0;

   return shaSuccess;
}

/*
 *  SHA1Result
 *
 *  Description:
 *   This function will return the 160-bit message digest into the
 *   Message_Digest array  provided by the caller.
 *   NOTE: The first octet of hash is stored in the 0th element,
 *         the last octet of hash in the 19th element.
 *
 *  Parameters:
 *   context: [in/out]
 *       The context to use to calculate the SHA-1 hash.
 *   Message_Digest: [out]
 *       Where the digest is returned.
 *
 *  Returns:
 *   sha Error Code.
 *
 */
int SHA1Result( SHA1Context *context,
               uint8_t Message_Digest[SHA1HashSize])
{
   int i;

   if (!context || !Message_Digest) {
      return shaNull;
   }

   if (context->Corrupted) {
      return context->Corrupted;
   }

   if (!context->Computed) {
      SHA1PadMessage(context);
      for (i = 0; i < 64; ++i) {
         /* message may be sensitive, clear it out */
         context->Message_Block[i] = 0;
      }
      context->Length_Low = 0;    /* and clear length */
      context->Length_High = 0;
      context->Computed = 1;
   }

   for (i = 0; i < SHA1HashSize; ++i) {
      Message_Digest[i] = context->Intermediate_Hash[i >> 2] >> 8 * ( 3 - ( i & 0x03 ) );
   }

   return shaSuccess;
}

/*
 *  SHA1Input
 *
 *  Description:
 *   This function accepts an array of octets as the next portion
 *   of the message.
 *
 *  Parameters:
 *   context: [in/out]
 *       The SHA 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:
 *   sha Error Code.
 *
 */
int SHA1Input(SHA1Context *context, const uint8_t *message_array, unsigned length)
{
   if (!length) {
      return shaSuccess;
   }

   if (!context || !message_array) {
      return shaNull;
   }

   if (context->Computed) {
      context->Corrupted = shaStateError;
      return shaStateError;
   }

   if (context->Corrupted) {
      return context->Corrupted;
   }

   while (length-- && !context->Corrupted) {
      context->Message_Block[context->Message_Block_Index++] = (*message_array & 0xFF);

      context->Length_Low += 8;
      if (context->Length_Low == 0) {
         context->Length_High++;
         if (context->Length_High == 0) {
            /* Message is too long */
            context->Corrupted = 1;
         }
      }

      if (context->Message_Block_Index == 64) {
         SHA1ProcessMessageBlock(context);
      }

      message_array++;
   }

   return shaSuccess;
}

/*
 *  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 this code, especially the
 *   single character names, were used because those were the
 *   names used in the publication.
 *
 *
 */
void SHA1ProcessMessageBlock(SHA1Context *context)
{
   const uint32_t K[] =     {     /* Constants defined in SHA-1  */
                            0x5A827999,
                            0x6ED9EBA1,
                            0x8F1BBCDC,
                            0xCA62C1D6
                            };
   int           t;                 /* Loop counter                */
   uint32_t    temp;              /* Temporary word value        */
   uint32_t    W[80];             /* Word sequence               */
   uint32_t    A, B, C, D, E;     /* Word buffers                */

   /*
    *  Initialize the first 16 words in the array W
    */
   for (t = 0; t < 16; t++) {
      W[t] = context->Message_Block[t * 4] << 24;
      W[t] |= context->Message_Block[t * 4 + 1] << 16;
      W[t] |= context->Message_Block[t * 4 + 2] << 8;
      W[t] |= 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->Intermediate_Hash[0];
   B = context->Intermediate_Hash[1];
   C = context->Intermediate_Hash[2];
   D = context->Intermediate_Hash[3];
   E = context->Intermediate_Hash[4];

   for (t = 0; t < 20; t++) {
      temp = SHA1CircularShift(5,A) + ((B & C) | ((~B) & D)) + E + W[t] + K[0];
      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];
      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];
      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];
      E = D;
      D = C;
      C = SHA1CircularShift(30,B);
      B = A;
      A = temp;
   }

   context->Intermediate_Hash[0] += A;
   context->Intermediate_Hash[1] += B;
   context->Intermediate_Hash[2] += C;
   context->Intermediate_Hash[3] += D;
   context->Intermediate_Hash[4] += E;

   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 the ProcessMessageBlock function
 *   provided appropriately.  When it returns, it can be assumed that
 *   the message digest has been computed.
 *
 *  Parameters:
 *   context: [in/out]
 *       The context to pad
 *   ProcessMessageBlock: [in]
 *       The appropriate SHA*ProcessMessageBlock function
 *  Returns:
 *   Nothing.
 *
 */

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;
   context->Message_Block[57] = context->Length_High >> 16;
   context->Message_Block[58] = context->Length_High >> 8;
   context->Message_Block[59] = context->Length_High;
   context->Message_Block[60] = context->Length_Low >> 24;
   context->Message_Block[61] = context->Length_Low >> 16;
   context->Message_Block[62] = context->Length_Low >> 8;
   context->Message_Block[63] = context->Length_Low;

   SHA1ProcessMessageBlock(context);
}

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