SHA1HashFunction.cc

/*
 * Copyright 2003 Michael A. Marsh, Cornell University. All rights reserved.
 * This software is released under the modified BSD license.
 * See the file LICENSE in the top-level directory for details.
 */
//
// $Id: SHA1HashFunction.cc,v 1.4 2004/05/19 15:56:47 mmarsh Exp $
//
// $Log: SHA1HashFunction.cc,v $
// Revision 1.4  2004/05/19 15:56:47  mmarsh
// *** empty log message ***
//
// Revision 1.3  2003/11/04 22:31:48  mmarsh
// *** empty log message ***
//
//

#include <openssl/sha.h>
#include <openssl/evp.h>

#include "SHA1HashFunction.h"

using namespace CODEX_Ciphers;

HashFunction::ustring*
SHA1HashFunction::operator()( const ustring& buff ) const
{
   EVP_MD_CTX ctx;
   EVP_DigestInit( &ctx, EVP_sha1() );
   EVP_DigestUpdate( &ctx, buff.data(), buff.length() );
   unsigned char output[ SHA_DIGEST_LENGTH ]; // 20 bytes = 160 bits
   unsigned int s;
   EVP_DigestFinal( &ctx, output, &s );
   return new ustring( output, SHA_DIGEST_LENGTH );
}

HashFunction::ustring*
SHA1HashFunction::operator()( const ustring& buff, unsigned int len ) const
{
   unsigned int bytesNeeded = (len+7)/8;
   EVP_MD_CTX ctx;
   EVP_MD_CTX_init( &ctx );
   ustring* retVal = new ustring;
   ustring junkBuff;

   // now loop
   unsigned char i = 0;
   while ( bytesNeeded > 0 )
   {
      junkBuff.push_back(i);
      i = ( i < 255 ) ? i+1 : 0;
      EVP_DigestInit_ex( &ctx, EVP_sha1(), 0 ); // uses default implementation
      EVP_DigestUpdate( &ctx, buff.data(), buff.length() );
      EVP_DigestUpdate( &ctx, junkBuff.data(), junkBuff.length() );
      unsigned char output[ SHA_DIGEST_LENGTH ]; // 20 bytes = 160 bits
      unsigned int s;
      EVP_DigestFinal_ex( &ctx, output, &s );
      unsigned int write_length = ( s < bytesNeeded ) ? s : bytesNeeded;
      retVal->reserve( retVal->capacity() + write_length );
      for ( unsigned int j = 0 ; j < write_length ; ++j )
      {
         retVal->push_back(output[j]);
      }
      bytesNeeded -= write_length;
   }

   EVP_MD_CTX_cleanup( &ctx );
   return retVal;
}

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