dkimsign.cpp

/*****************************************************************************
*  Copyright 2005 Alt-N Technologies, Ltd.
*
*  Licensed under the Apache License, Version 2.0 (the "License");
*  you may not use this file except in compliance with the License.
*  You may obtain a copy of the License at
*
*      http://www.apache.org/licenses/LICENSE-2.0
*
*  This code incorporates intellectual property owned by Yahoo! and licensed
*  pursuant to the Yahoo! DomainKeys Patent License Agreement.
*
*  Unless required by applicable law or agreed to in writing, software
*  distributed under the License is distributed on an "AS IS" BASIS,
*  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*  See the License for the specific language governing permissions and
*  limitations under the License.
*
*****************************************************************************/

#define _strnicmp strncasecmp
#define _stricmp strcasecmp
#define LOWORD(l) ((unsigned)(l) & 0xffff)
#define HIWORD(l) ((unsigned)(l) >> 16)

#include <string.h>
#include <map>

#include "dkim.h"
#include "dkimsign.h"


CDKIMSign::CDKIMSign()
{
	m_EmptyLineCount = 0;
	m_pfnHdrCallback = NULL;

	EVP_SignInit( &m_allman_sha1ctx, EVP_sha1() );
	EVP_SignInit( &m_Hdr_ietf_sha1ctx, EVP_sha1() );
	EVP_SignInit( &m_Hdr_ietf_sha256ctx, EVP_sha256() );
	EVP_DigestInit( &m_Bdy_ietf_sha1ctx, EVP_sha1() );
	EVP_DigestInit( &m_Bdy_ietf_sha256ctx, EVP_sha256() );
}

CDKIMSign::~CDKIMSign()
{
	EVP_MD_CTX_cleanup( &m_allman_sha1ctx );
	EVP_MD_CTX_cleanup( &m_Hdr_ietf_sha1ctx );
	EVP_MD_CTX_cleanup( &m_Hdr_ietf_sha256ctx );
	EVP_MD_CTX_cleanup( &m_Bdy_ietf_sha1ctx );
	EVP_MD_CTX_cleanup( &m_Bdy_ietf_sha256ctx );
}

////////////////////////////////////////////////////////////////////////////////
// 
// Init - save the options
//
////////////////////////////////////////////////////////////////////////////////
int CDKIMSign::Init( DKIMSignOptions* pOptions )
{
	int nRet = CDKIMBase::Init();

	m_Canon = pOptions->nCanon;

	// as of draft 01, these are the only allowed signing types:
	if(     (m_Canon != DKIM_SIGN_SIMPLE_RELAXED) 
		 && (m_Canon != DKIM_SIGN_RELAXED)
		 && (m_Canon != DKIM_SIGN_RELAXED_SIMPLE) )
	{
		m_Canon = DKIM_SIGN_SIMPLE;
	}

	sSelector.assign( pOptions->szSelector );

	m_pfnHdrCallback = pOptions->pfnHeaderCallback;

	sDomain.assign( pOptions->szDomain );

	m_IncludeBodyLengthTag = ( pOptions->nIncludeBodyLengthTag != 0 );

	m_nBodyLength = 0;

	m_ExpireTime = pOptions->expireTime;

	sIdentity.assign( pOptions->szIdentity );

	m_nIncludeTimeStamp = pOptions->nIncludeTimeStamp;
	m_nIncludeQueryMethod = pOptions->nIncludeQueryMethod;
	m_nIncludeCopiedHeaders = pOptions->nIncludeCopiedHeaders;
	m_nIncludeBodyHash = pOptions->nIncludeBodyHash;

	// NOTE: the following line is not backwards compatible with MD 8.0.3
	// because the szRequiredHeaders member was added after the release
	//sRequiredHeaders.assign( pOptions->szRequiredHeaders );

	//make sure there is a colon after the last header in the list
	if( (sRequiredHeaders.size() > 0) && sRequiredHeaders.at(sRequiredHeaders.size()-1) != ':' )
	{
		sRequiredHeaders.append( ":" );
	}

	m_nHash = pOptions->nHash;

	m_bReturnedSigAssembled = false;

	m_sCopiedHeaders.erase();

	return nRet;
}

//FILE* fpdebug = NULL;


////////////////////////////////////////////////////////////////////////////////
// 
// Hash - update the hash
//
////////////////////////////////////////////////////////////////////////////////
void CDKIMSign::Hash( const char* szBuffer, int nBufLength, bool bHdr, bool bAllmanOnly )
{
	/** START DEBUG CODE **
	if( nBufLength == 2 && szBuffer[0] == '\r' && szBuffer[1] == '\n' )
	{
		printf( "[CRLF]\n" );
	}
	else
	{
		char* szDbg = new char[nBufLength+1];
		strncpy( szDbg, szBuffer, nBufLength );
		szDbg[nBufLength] = '\0';
		printf( "[%s]\n", szDbg );
	} ***

	if( fpdebug == NULL )
	{
		fpdebug = fopen( "canon.msg", "wb" );
	}

	fwrite( szBuffer, 1, nBufLength, fpdebug );

	** END DEBUG CODE **/

	if( bAllmanOnly )
	{
		if( m_nIncludeBodyHash & DKIM_BODYHASH_ALLMAN_1 )
		{
			EVP_SignUpdate( &m_allman_sha1ctx, szBuffer, nBufLength );
		}
	}
	else
	{
		if( m_nIncludeBodyHash < DKIM_BODYHASH_IETF_1 )
		{
			EVP_SignUpdate( &m_allman_sha1ctx, szBuffer, nBufLength );
		}
		else if( m_nIncludeBodyHash & DKIM_BODYHASH_IETF_1 )
		{
			if( m_nIncludeBodyHash & DKIM_BODYHASH_ALLMAN_1 )
			{
				EVP_SignUpdate( &m_allman_sha1ctx, szBuffer, nBufLength );
			}
			if( m_nHash & DKIM_HASH_SHA256 )
			{
				if( bHdr )
					EVP_SignUpdate( &m_Hdr_ietf_sha256ctx, szBuffer, nBufLength );
				else
					EVP_DigestUpdate( &m_Bdy_ietf_sha256ctx, szBuffer, nBufLength );
			}
			if( m_nHash != DKIM_HASH_SHA256 )
			{
				if( bHdr )
					EVP_SignUpdate( &m_Hdr_ietf_sha1ctx, szBuffer, nBufLength );
				else
					EVP_DigestUpdate( &m_Bdy_ietf_sha1ctx, szBuffer, nBufLength );
			}
		}
	}
}


////////////////////////////////////////////////////////////////////////////////
// 
// SignThisTag - return boolean whether or not to sign this tag
//
////////////////////////////////////////////////////////////////////////////////
bool CDKIMSign::SignThisTag( const string& sTag )
{
	bool bRet = true;

	if( _strnicmp( sTag.c_str(), "X-", 2 ) == 0 || 
		_stricmp( sTag.c_str(), "Authentication-Results:" ) == 0 ||
		_stricmp( sTag.c_str(), "Return-Path:" ) == 0 )
	{
		bRet = false;
	}

	return bRet;
}


bool ConvertHeaderToQuotedPrintable(const char *source, char* dest)
{
	bool bConvert = false;

	// do quoted printable
	static unsigned char hexchars[16] = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};

	unsigned char *d = (unsigned char*)dest;
	for (const unsigned char *s = (const unsigned char *)source; *s != '\0'; s++)
	{
		if (*s >= 33 && *s <= 126 && *s != '=' && *s != ':' && *s != ';' && *s != '|')
		{
			*d++ = *s;
		}
		else
		{
			bConvert = true;
			*d++ = '=';
			*d++ = hexchars[*s >> 4];
			*d++ = hexchars[*s & 15];
		}
	}
	*d = '\0';

	return bConvert;
}

////////////////////////////////////////////////////////////////////////////////
// 
// GetHeaderParams - Extract any needed header parameters
//
////////////////////////////////////////////////////////////////////////////////
void CDKIMSign::GetHeaderParams( const string& sHdr )
{
	if ( _strnicmp( sHdr.c_str(), "X", 1) == 0)
		return;

	if( _strnicmp( sHdr.c_str(), "From:", 5 ) == 0 )
	{
		sFrom.assign( sHdr.c_str() + 5 );
	}
	if( _strnicmp( sHdr.c_str(), "Sender:", 7 ) == 0 )
	{
		sSender.assign( sHdr.c_str() + 7 );
	}	

	if( m_nIncludeCopiedHeaders )
	{
		string::size_type pos = sHdr.find( ':' );

		if( pos != string::npos )
		{
			string sTag, sValue;
			char* workBuffer = new char[sHdr.size() * 3 + 1];

			sTag.assign( sHdr.substr( 0, pos ) );
			sValue.assign( sHdr.substr( pos+1, string::npos ) );

			ConvertHeaderToQuotedPrintable( sTag.c_str(), workBuffer );

			if( !m_sCopiedHeaders.empty() )
			{
				m_sCopiedHeaders.append( "|" );
			}

			m_sCopiedHeaders.append( workBuffer );
			m_sCopiedHeaders.append( ":" );

			ConvertHeaderToQuotedPrintable( sValue.c_str(), workBuffer );

			m_sCopiedHeaders.append( workBuffer );

			delete[] workBuffer;
		}
	}
}


////////////////////////////////////////////////////////////////////////////////
// 
// ProcessHeaders - sign headers and save needed parameters
//
////////////////////////////////////////////////////////////////////////////////
int CDKIMSign::ProcessHeaders(void)
{
	map<string,list<string>::reverse_iterator> IterMap;
	map<string,list<string>::reverse_iterator>::iterator IterMapIter;
	list<string>::reverse_iterator riter;
	list<string>::iterator iter;
	string sTag;
	bool bFromHeaderFound = false;

	// walk the header list
	for( iter = HeaderList.begin(); iter != HeaderList.end(); iter++ )
	{
		sTag.assign( *iter );

		// look for a colon
		string::size_type pos = sTag.find( ':' );

		if (pos != string::npos)
		{
			int nSignThisTag = 1;

			// hack off anything past the colon
			sTag.erase( pos + 1, string::npos );

			// is this the From: header?
			if( _stricmp( sTag.c_str(), "From:" ) == 0 )
			{
				bFromHeaderFound = true;
				nSignThisTag = 1;
				IsRequiredHeader( sTag );  // remove from required header list
			}
			// is this in the list of headers that must be signed?
			else if( IsRequiredHeader( sTag ) )
			{
				nSignThisTag = 1;
			}
			else
			{
				if( m_pfnHdrCallback )
				{
					nSignThisTag = m_pfnHdrCallback( iter->c_str() );
				}
				else
				{
					nSignThisTag = SignThisTag( sTag ) ? 1 : 0;
				}
			}

			// save header parameters
			GetHeaderParams( *iter );

			if( nSignThisTag > 0 )
			{
				// add this tag to h=
				hParam.append( sTag );

				IterMapIter = IterMap.find( sTag );

				riter = ( IterMapIter == IterMap.end() ) ? HeaderList.rbegin() : IterMapIter->second;

				// walk the list in reverse looking for the last instance of this header
				while ( riter != HeaderList.rend() )
				{
					if( _strnicmp( riter->c_str(), sTag.c_str(), sTag.size() ) == 0 )
					{
						ProcessHeader( *riter );

						// save the reverse iterator position for this tag
						riter++;
						IterMap[sTag] = riter;
						break;
					}
					riter++;
				} 
			}
		}
	}

	Hash( "\r\n", 2, true, true ); // only for Allman sig

	if( !bFromHeaderFound )
	{
		string sFrom( "From:" );
		hParam.append( sFrom );
		IsRequiredHeader( sFrom ); // remove from required header list
//		Hash( "\r\n", 2 );
	}

	hParam.append( sRequiredHeaders );

//	string::size_type end = sRequiredHeaders.find( ':' );
//	while (end != string::npos)
//	{
//		Hash( "\r\n", 2 );
//		end = sRequiredHeaders.find( ':', end+1 );
//	}

	// remove the last colon from h=
	if( hParam.at( hParam.size() - 1 ) == ':' )
		hParam.erase( hParam.size() - 1, string::npos );

	return DKIM_SUCCESS;
}



void CDKIMSign::ProcessHeader( const string& sHdr )
{
	switch( HIWORD( m_Canon ) )
	{
	case DKIM_CANON_SIMPLE:
		Hash( sHdr.c_str(), sHdr.size(), true );
		Hash( "\r\n", 2, true );
		break;

	case DKIM_CANON_NOWSP:
		{
			string sTemp = sHdr;
			RemoveSWSP( sTemp );

			// convert characters before ':' to lower case
			for( char* s = (char*)sTemp.c_str(); *s != '\0' && *s != ':'; s++ )
			{
				if( *s >= 'A' && *s <= 'Z' )
					*s += 'a'-'A';
			}

			Hash( sTemp.c_str(), sTemp.size(), true );
			Hash( "\r\n", 2, true );
		}
		break;

	case DKIM_CANON_RELAXED:
		{
			string sTemp = RelaxHeader( sHdr );
			Hash( sTemp.c_str(), sTemp.length(), true );
			Hash( "\r\n", 2, true );
		}
		break;	
	}
}


int CDKIMSign::ProcessBody( char* szBuffer, int nBufLength, bool bEOF )
{
	switch( LOWORD( m_Canon ) )
	{
	case DKIM_CANON_SIMPLE:
		if( nBufLength > 0 )
		{
			while( m_EmptyLineCount > 0 )
			{
				Hash( "\r\n", 2, false );
				m_nBodyLength += 2;
				m_EmptyLineCount--;
			}
			Hash( szBuffer, nBufLength, false );
			Hash( "\r\n", 2, false );
			m_nBodyLength += nBufLength + 2;
		}
		else
		{
			m_EmptyLineCount++;
			if( bEOF )
			{
				Hash( "\r\n", 2, false );
				m_nBodyLength += 2;
			}
		}
		break;

	case DKIM_CANON_NOWSP:
		RemoveSWSP( szBuffer, nBufLength );
		if( nBufLength > 0 )
		{
			Hash( szBuffer, nBufLength, false );
			m_nBodyLength += nBufLength;
		}
		break;

	case DKIM_CANON_RELAXED:
		CompressSWSP( szBuffer, nBufLength );
		if( nBufLength > 0 )
		{
			while( m_EmptyLineCount > 0 )
			{
				Hash( "\r\n", 2, false );
				m_nBodyLength += 2;
				m_EmptyLineCount--;
			}
			Hash( szBuffer, nBufLength, false );
			m_nBodyLength += nBufLength;
			if ( !bEOF )
			{
				Hash( "\r\n", 2, false );
				m_nBodyLength += 2;
			}
		}
		else
			m_EmptyLineCount++;
		break;
	}

	return DKIM_SUCCESS;
}

bool CDKIMSign::ParseFromAddress( void )
{
	string::size_type pos;
	string sAddress;

	if( !sFrom.empty() )
	{
		sAddress.assign( sFrom );
	}
	else if( !sSender.empty() )
	{
		sAddress.assign( sSender );
	}
	else
	{
		return false;
	}

	// simple for now, beef it up later

	// remove '<' and anything before it
	pos = sAddress.find( '<' );
	if( pos != string::npos )
		sAddress.erase( 0, pos );

	// remove '>' and anything after it
	pos = sAddress.find( '>' );
	if( pos != string::npos )
		sAddress.erase( pos, string::npos );

	// look for '@' symbol
	pos = sAddress.find( '@' );
	if( pos == string::npos )
		return false;

	if( sDomain.empty() )
	{
		sDomain.assign( sAddress.c_str() + pos + 1 );
		RemoveSWSP( sDomain );
	}

	return true;
}

////////////////////////////////////////////////////////////////////////////////
// 
// InitSig - initialize signature folding algorithm
//
////////////////////////////////////////////////////////////////////////////////
void CDKIMSign::InitSig(void)
{
	m_sSig.reserve( 1024 );
	m_sSig.assign( "DKIM-Signature:" );
	m_nSigPos = m_sSig.size();
}

////////////////////////////////////////////////////////////////////////////////
// 
// AddTagToSig - add tag and value to signature folding if necessary
//               if bFold, fold at cbrk char
//
////////////////////////////////////////////////////////////////////////////////
void CDKIMSign::AddTagToSig( const char* const Tag, const string &sValue, char cbrk, bool bFold )
{
	int nTagLen = strlen(Tag);

	AddInterTagSpace( (!bFold) ? sValue.size() + nTagLen + 2 : nTagLen + 2 );

	m_sSig.append( Tag );
	m_sSig.append( "=" );
	m_nSigPos += 1 + nTagLen;

	if( !bFold )
	{
		m_sSig.append( sValue );
		m_nSigPos += sValue.size();
	}
	else
	{
		AddFoldedValueToSig( sValue, cbrk );
	}
	m_sSig.append( ";" );
	m_nSigPos++;
}

////////////////////////////////////////////////////////////////////////////////
// 
// AddTagToSig - add tag and numeric value to signature folding if necessary
//
////////////////////////////////////////////////////////////////////////////////
void CDKIMSign::AddTagToSig( const char* const Tag, unsigned long nValue )
{
	char szValue[64];
	sprintf( szValue, "%lu", nValue );
	AddTagToSig( Tag, szValue, 0, false );
}

////////////////////////////////////////////////////////////////////////////////
// 
// AddInterTagSpace - add space or fold here
//
////////////////////////////////////////////////////////////////////////////////
void CDKIMSign::AddInterTagSpace( int nSizeOfNextTag )
{
	if( m_nSigPos + nSizeOfNextTag + 1 > OptimalHeaderLineLength )
	{
		m_sSig.append( "\r\n\t" );
		m_nSigPos = 1;
	}
	else
	{
		m_sSig.append( " " );
		m_nSigPos++;
	}
}

////////////////////////////////////////////////////////////////////////////////
// 
// AddTagToSig - add value to signature folding if necessary
//               if cbrk == 0 fold anywhere, otherwise fold only at cbrk
//
////////////////////////////////////////////////////////////////////////////////
void CDKIMSign::AddFoldedValueToSig( const string &sValue, char cbrk )
{
	string::size_type pos = 0;

	if( cbrk == 0 )
	{
		// fold anywhere
		while( pos < sValue.size() )
		{
			string::size_type len = OptimalHeaderLineLength - m_nSigPos;
			if( len > sValue.size() - pos )
				len = sValue.size() - pos;
			m_sSig.append( sValue.substr( pos, len ) );
			m_nSigPos += len;
			pos += len;

			if( pos < sValue.size() )
			{
				m_sSig.append( "\r\n\t" );
				m_nSigPos = 1;
			}
		}
	}
	else
	{
		// fold only at cbrk
		while( pos < sValue.size() )
		{
			string::size_type len = OptimalHeaderLineLength - m_nSigPos;
			string::size_type brkpos;
			
			if( sValue.size() - pos < len )
			{
				brkpos = sValue.size() - 1;
			}
			else
			{
				brkpos = sValue.rfind( cbrk, pos + len );
			}

			if( brkpos == string::npos || brkpos < pos )
			{
				brkpos = sValue.find( cbrk, pos );
				if( brkpos == string::npos )
				{
					brkpos = sValue.size();
				}
			}

			len = brkpos - pos + 1;

			m_sSig.append( sValue.substr( pos, len ) );

			m_nSigPos += len;
			pos += len;

			if( pos < sValue.size() )
			{
				m_sSig.append( "\r\n\t" );
				m_nSigPos = 1;
			}
		}
	}
}


////////////////////////////////////////////////////////////////////////////////
// 
// GetSig - compute hash and return signature header in szSignature
//
////////////////////////////////////////////////////////////////////////////////
int CDKIMSign::GetSig( char* szPrivKey, char* szSignature, unsigned nSigLength )
{
	if( szPrivKey == NULL )
	{
		return DKIM_BAD_PRIVATE_KEY;
	}

	if( szSignature == NULL )
	{
		return DKIM_BUFFER_TOO_SMALL;
	}

	int nRet = AssembleReturnedSig( szPrivKey );

	if( nRet != DKIM_SUCCESS )
		return nRet;

	if( m_sReturnedSig.size() + 1 < nSigLength )
	{
		strcpy( szSignature, m_sReturnedSig.c_str() );
	}
	else
	{
		return DKIM_BUFFER_TOO_SMALL; 
	}

	return DKIM_SUCCESS;
}


////////////////////////////////////////////////////////////////////////////////
// 
// GetSig - compute hash and return signature header in szSignature
//
////////////////////////////////////////////////////////////////////////////////
int CDKIMSign::GetSig2( char* szPrivKey, char** pszSignature )
{
	if( szPrivKey == NULL )
	{
		return DKIM_BAD_PRIVATE_KEY;
	}

	if( pszSignature == NULL )
	{
		return DKIM_BUFFER_TOO_SMALL;
	}

	int nRet = AssembleReturnedSig( szPrivKey );

	if( nRet != DKIM_SUCCESS )
		return nRet;

	*pszSignature = (char*)m_sReturnedSig.c_str();

	return DKIM_SUCCESS;

}


////////////////////////////////////////////////////////////////////////////////
// 
// IsRequiredHeader - Check if header in required list. If so, delete
//                    header from list.
//
////////////////////////////////////////////////////////////////////////////////
bool CDKIMSign::IsRequiredHeader( const string& sTag )
{
	string::size_type start = 0;
	string::size_type end = sRequiredHeaders.find( ':' );

	while (end != string::npos)
	{
		// check for a zero-length header
		if( start == end )
		{
			sRequiredHeaders.erase( start, 1 );
		}
		else
		{
			if( _stricmp( sTag.c_str(), sRequiredHeaders.substr( start, end - start + 1 ).c_str() ) == 0 )
			{
				sRequiredHeaders.erase( start, end - start + 1 );
				return true;
			}
			else
			{
				start = end + 1;
			}
		}

		end = sRequiredHeaders.find( ':', start );
	}

	return false;
}



int CDKIMSign::ConstructSignature( char* szPrivKey, bool bUseIetfBodyHash, bool bUseSha256 )
{
  string sSignedSig;
  unsigned char* sig;
  EVP_PKEY *pkey;
  BIO *bio, *b64;
  unsigned int siglen;
  int size;
  int len;
  char* buf;

  /* construct the DKIM-Signature: header and add to hash */
  InitSig();

  if( bUseIetfBodyHash ) { AddTagToSig( "v", "1", 0, false ); }

  AddTagToSig( "a", bUseSha256 ? "rsa-sha256" : "rsa-sha1", 0, false );

  switch( m_Canon ) {
    case DKIM_SIGN_SIMPLE:
//        AddTagToSig( "c", "simple", 0, false );
        AddTagToSig( "c", "simple/simple", 0, false );
        break;
    case DKIM_SIGN_SIMPLE_RELAXED:
        AddTagToSig( "c", "simple/relaxed", 0, false );
        break;
    case DKIM_SIGN_RELAXED:
        AddTagToSig( "c", "relaxed/relaxed", 0, false );
        break;
    case DKIM_SIGN_RELAXED_SIMPLE:
//      AddTagToSig( "c", "relaxed", 0, false );   // --> orig line
        AddTagToSig( "c", "relaxed/simple", 0, false );
        break;
  }

  AddTagToSig( "d", sDomain, 0, false );
  AddTagToSig( "s", sSelector, 0, false );

  if( m_IncludeBodyLengthTag ) { AddTagToSig( "l", m_nBodyLength ); }

  if( m_nIncludeTimeStamp != 0 ) {
    time_t t;
    time( &t );
    AddTagToSig( "t", t );
  }

  if( m_ExpireTime != 0 ) { AddTagToSig( "x", m_ExpireTime ); }

  if( !sIdentity.empty() ) { AddTagToSig( "i", sIdentity, 0, false ); }

  if( m_nIncludeQueryMethod ) { 
    AddTagToSig( "q", bUseIetfBodyHash ? "dns/txt" : "dns" , 0, false );
  }

  AddTagToSig( "h", hParam, ':', true );

  if( m_nIncludeCopiedHeaders ) { AddTagToSig( "z", m_sCopiedHeaders, 0, true ); }

  if( bUseIetfBodyHash )
  {
    unsigned char Hash[EVP_MAX_MD_SIZE];
    unsigned int nHashLen = 0;

    EVP_DigestFinal( bUseSha256 ? &m_Bdy_ietf_sha256ctx : &m_Bdy_ietf_sha1ctx, Hash, &nHashLen );

    bio = BIO_new(BIO_s_mem());
    if (!bio) {
      return DKIM_OUT_OF_MEMORY; 
    }
    b64 = BIO_new(BIO_f_base64());
    if (!b64) 
    {
      BIO_free(bio);
      return DKIM_OUT_OF_MEMORY;
    }
    BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL);
    BIO_push(b64, bio);
    if (BIO_write(b64, Hash, nHashLen) < (int)nHashLen) 
    {
      BIO_free_all(b64);
      return DKIM_OUT_OF_MEMORY;
    }
    BIO_flush(b64);

    len = nHashLen * 2;
    buf = new char[len];

    if( buf == NULL )
    {
      BIO_free_all(b64);
      return DKIM_OUT_OF_MEMORY;
    }

    size = BIO_read(bio, buf, len);
    BIO_free_all(b64);

    // this should never happen
    if (size >= len)
    {
       delete[] buf;
       return DKIM_OUT_OF_MEMORY;  
    }

    buf[size] = '\0';

    AddTagToSig( "bh", buf, 0, true );

    delete[] buf;
  }

  AddInterTagSpace( 3 );

  m_sSig.append( "b=" );
  m_nSigPos += 2;

  // Force a full copy - no reference copies please
  sSignedSig.assign( m_sSig.c_str() );

  // note that since we're not calling hash here, need to dump this
  // to the debug file if you want the full canonical form

  string sTemp;

  if( HIWORD(m_Canon) == DKIM_CANON_RELAXED ) {
    sTemp = RelaxHeader( sSignedSig );
  } else {
    sTemp = sSignedSig.c_str();
  }

  if( bUseIetfBodyHash ) {
    EVP_SignUpdate( bUseSha256 ? &m_Hdr_ietf_sha256ctx : &m_Hdr_ietf_sha1ctx, sTemp.c_str(), sTemp.size() );
  } else {
    EVP_SignUpdate( &m_allman_sha1ctx, sTemp.c_str(), sTemp.size() );
  }

  bio = BIO_new_mem_buf(szPrivKey, -1);
  if( bio == NULL )
    return DKIM_OUT_OF_MEMORY;

  pkey = PEM_read_bio_PrivateKey(bio, NULL, NULL, NULL);
  BIO_free(bio);

  if (!pkey) { return DKIM_BAD_PRIVATE_KEY; }

  siglen = EVP_PKEY_size(pkey);
  int nSignRet;

  sig = (unsigned char*) OPENSSL_malloc(siglen);
  if( sig == NULL )
  {
    EVP_PKEY_free(pkey);
    return DKIM_OUT_OF_MEMORY;
  }

  if( bUseIetfBodyHash )
  {
    nSignRet = EVP_SignFinal( bUseSha256 ? &m_Hdr_ietf_sha256ctx : &m_Hdr_ietf_sha1ctx, sig, &siglen, pkey);
  } else {
    nSignRet = EVP_SignFinal( &m_allman_sha1ctx, sig, &siglen, pkey);
  }

  EVP_PKEY_free(pkey);

  if( !nSignRet )
  {
    OPENSSL_free(sig);
    return DKIM_BAD_PRIVATE_KEY; // key too small
  }

  bio = BIO_new(BIO_s_mem());
  if (!bio) {
    return DKIM_OUT_OF_MEMORY; 
  }
  b64 = BIO_new(BIO_f_base64());
  if (!b64) {
    BIO_free(bio);
    return DKIM_OUT_OF_MEMORY;
  }
  BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL);
  BIO_push(b64, bio);
  if (BIO_write(b64, sig, siglen) < (int)siglen) 
  {
    OPENSSL_free(sig);
    BIO_free_all(b64);
    return DKIM_OUT_OF_MEMORY;
  }
  BIO_flush(b64);
  OPENSSL_free(sig);

  len = siglen * 2;
  buf = new char[len];

  if( buf == NULL )
  {
    BIO_free_all(b64);
    return DKIM_OUT_OF_MEMORY;
  }

  size = BIO_read(bio, buf, len);
  BIO_free_all(b64);

  // this should never happen
  if (size >= len) {
    delete[] buf;
    return DKIM_OUT_OF_MEMORY;  
  }

  buf[size] = '\0';
  AddFoldedValueToSig( buf, 0 );
  delete[] buf;
  return DKIM_SUCCESS;
}

int CDKIMSign::AssembleReturnedSig( char* szPrivKey )
{
  int nRet;

  if( m_bReturnedSigAssembled )
    return DKIM_SUCCESS;

  ProcessFinal();

	if( ParseFromAddress() == false )
	{
		//return DKIM_NO_SENDER;
	}

  Hash( "\r\n", 2, true, true ); // only for Allman sig

  string allmansha1sig, ietfsha256Sig, ietfsha1Sig;

  if( m_nIncludeBodyHash < DKIM_BODYHASH_IETF_1 )
  {
    nRet = ConstructSignature( szPrivKey, false, false );
    if( nRet == DKIM_SUCCESS )
    {
      allmansha1sig.assign( m_sSig );
    } else {
      return nRet;
    }
  }
  else if( m_nIncludeBodyHash & DKIM_BODYHASH_IETF_1 )
  {
    if( m_nIncludeBodyHash & DKIM_BODYHASH_ALLMAN_1 )
    {
      nRet = ConstructSignature( szPrivKey, false, false );
      if( nRet == DKIM_SUCCESS ) {
        allmansha1sig.assign( m_sSig );
      } else {
        return nRet;
      }
    }
    if( m_nHash & DKIM_HASH_SHA256 )
    {
      nRet = ConstructSignature( szPrivKey, true, true );
        if( nRet == DKIM_SUCCESS )
        {
          ietfsha256Sig.assign( m_sSig );
        } else {
          return nRet;
        }
    }
    if( m_nHash != DKIM_HASH_SHA256 )
    {
      nRet = ConstructSignature( szPrivKey, true, false );
      if( nRet == DKIM_SUCCESS )
      {
        ietfsha1Sig.assign( m_sSig );
      } else {
        return nRet;
      }
    }
  }


//	fclose( fpdebug );
//	fpdebug = NULL;

  m_sReturnedSig.assign( allmansha1sig );

  if( !ietfsha1Sig.empty() )
  {
    if( !m_sReturnedSig.empty() )
    {
      m_sReturnedSig.append( "\r\n" );
    }
    m_sReturnedSig.append( ietfsha1Sig );
  }

  if( !ietfsha256Sig.empty() )
  {
    if( !m_sReturnedSig.empty() )
    {
      m_sReturnedSig.append( "\r\n" );
    }
    m_sReturnedSig.append( ietfsha256Sig );
  }

  m_bReturnedSigAssembled = true;
  return DKIM_SUCCESS;
}