env_enc.c

老外写的加密库cryptlib(版本3.1)

		if( cryptStatusError( status ) )
			return( status );
		}

	/* Remember how much data is now available to be read out */
	envelopeInfoPtr->segmentDataEnd = envelopeInfoPtr->bufPos;

	/* Mark this segment as being completed */
	envelopeInfoPtr->dataFlags |= ENVDATA_SEGMENTCOMPLETE;

	return( CRYPT_OK );
	}

/****************************************************************************
*																			*
*								Copy to Envelope							*
*																			*
****************************************************************************/

/* Copy data into the envelope.  Returns the number of bytes copied, or an
   overflow error if we're trying to flush data and there isn't room to
   perform the flush (this somewhat peculiar case is because the caller
   expects to have 0 bytes copied in this case) */

static int copyToEnvelope( ENVELOPE_INFO *envelopeInfoPtr, 
						   const BYTE *buffer, const int length )
	{
	ACTION_LIST *hashActionPtr;
	BOOLEAN needCompleteSegment = FALSE;
	BYTE *bufPtr;
	int bytesToCopy, status;

	assert( isWritePtr( envelopeInfoPtr, sizeof( ENVELOPE_INFO ) ) );
	assert( length >= 0 );
	assert( isReadPtr( buffer, length ) );

	/* Perform a safety check of the envelope state */
	if( envelopeInfoPtr->bufPos < 0 || \
		envelopeInfoPtr->bufPos > envelopeInfoPtr->bufSize )
		{
		assert( NOTREACHED );
		return( CRYPT_ERROR_OVERFLOW );
		}

	/* If we're trying to copy into a full buffer, return a count of 0 bytes
	   unless we're trying to flush the buffer (the calling routine may
	   convert this to an overflow error if necessary) */
	if( envelopeInfoPtr->bufPos >= envelopeInfoPtr->bufSize )
		return( length > 0 ? 0 : CRYPT_ERROR_OVERFLOW );

	/* If we're generating a detached signature, just hash the data and
	   exit */
	if( envelopeInfoPtr->flags & ENVELOPE_DETACHED_SIG )
		{
		/* Unlike CMS, PGP handles authenticated attributes by extending the 
		   hashing of the payload data to cover the additional attributes,
		   so if this is a flush and we're using the PGP format we can't 
		   wrap up the hashing yet */
		if( length <= 0 && envelopeInfoPtr->type == CRYPT_FORMAT_PGP )
			return( 0 );

		assert( envelopeInfoPtr->actionList != NULL );
		for( hashActionPtr = envelopeInfoPtr->actionList;
			 hashActionPtr != NULL && hashActionPtr->action == ACTION_HASH; 
			 hashActionPtr = hashActionPtr->next )
			{
			status = krnlSendMessage( hashActionPtr->iCryptHandle,
									  IMESSAGE_CTX_HASH, ( void * ) buffer, 
									  length );
			if( cryptStatusError( status ) )
				return( status );
			}
		return( length );
		}

	/* If we're flushing data, wrap up the segment and exit */
	if( length <= 0 )
		{
		BOOLEAN needNewSegment = envelopeInfoPtr->dataFlags & \
								 ENVDATA_NEEDSPADDING;

#ifdef USE_COMPRESSION
		/* If we're using compression, flush any remaining data out of the
		   zStream */
		if( envelopeInfoPtr->flags & ENVELOPE_ZSTREAMINITED )
			{
			/* If we've just completed a segment, begin a new one.  This
			   action is slightly anomalous in that normally a flush can't
			   add more data to the envelope and so we'd never need to start
			   a new segment during a flush, however since we can have
			   arbitrarily large amounts of data trapped in subspace via zlib
			   we need to be able to handle starting new segments at this
			   point */
			if( envelopeInfoPtr->dataFlags & ENVDATA_SEGMENTCOMPLETE )
				{
				status = beginSegment( envelopeInfoPtr );
				if( cryptStatusError( status ) )
					return( status );
				if( envelopeInfoPtr->bufPos >= envelopeInfoPtr->bufSize )
					return( CRYPT_ERROR_OVERFLOW );
				}

			/* Flush any remaining compressed data into the envelope buffer */
			bytesToCopy = envelopeInfoPtr->bufSize - envelopeInfoPtr->bufPos;
			envelopeInfoPtr->zStream.next_in = NULL;
			envelopeInfoPtr->zStream.avail_in = 0;
			envelopeInfoPtr->zStream.next_out = envelopeInfoPtr->buffer + \
												envelopeInfoPtr->bufPos;
			envelopeInfoPtr->zStream.avail_out = bytesToCopy;
			status = deflate( &envelopeInfoPtr->zStream, Z_FINISH );
			if( status != Z_STREAM_END && status != Z_OK )
				/* There was some problem other than the output buffer being
				   full */
				return( CRYPT_ERROR_FAILED );

			/* Adjust the status information based on the data flushed out
			   of the zStream.  We don't need to check for the output buffer
			   being full because this case is already handled by the check
			   of the deflate() return value */
			envelopeInfoPtr->bufPos += bytesToCopy - \
									   envelopeInfoPtr->zStream.avail_out;
			assert( envelopeInfoPtr->bufPos >= 0 && \
					envelopeInfoPtr->bufPos <= envelopeInfoPtr->bufSize );

			/* If we didn't finish flushing data because the output buffer is
			   full, complete the segment and tell the caller that they need 
			   to pop some data */
			if( status == Z_OK )
				{
				status = completeSegment( envelopeInfoPtr, TRUE );
				return( cryptStatusError( status ) ? \
						status : CRYPT_ERROR_OVERFLOW );
				}
			}
#endif /* USE_COMPRESSION */

		/* If we're encrypting data with a block cipher, we need to add PKCS
		   #5 padding at the end of the last block */
		if( envelopeInfoPtr->blockSize > 1 )
			{
			envelopeInfoPtr->dataFlags |= ENVDATA_NEEDSPADDING;
			if( envelopeInfoPtr->dataFlags & ENVDATA_SEGMENTCOMPLETE )
				/* The current segment has been wrapped up, we need to begin
				   a new segment to contain the padding */
				needNewSegment = TRUE;
			}

		/* If we're carrying over the padding requirement from a previous
		   block, we need to begin a new block before we can try and add the
		   padding.  This can happen if there was data left after the 
		   previous segment was completed or if the addition of padding 
		   would have overflowed the buffer when the segment was completed, 
		   in other words if the needPadding flag is still set from the 
		   previous call */
		if( needNewSegment )
			{
			status = beginSegment( envelopeInfoPtr );
			if( cryptStatusError( status ) )
				return( status );
			if( envelopeInfoPtr->bufPos >= envelopeInfoPtr->bufSize )
				return( CRYPT_ERROR_OVERFLOW );
			}

		/* Complete the segment if necessary */
		if( !( envelopeInfoPtr->dataFlags & ENVDATA_SEGMENTCOMPLETE ) || \
			( envelopeInfoPtr->dataFlags & ENVDATA_NEEDSPADDING ) )
			{
			status = completeSegment( envelopeInfoPtr, TRUE );
			if( cryptStatusError( status ) )
				return( status );
			}
		if( envelopeInfoPtr->dataFlags & ENVDATA_NEEDSPADDING )
			return( CRYPT_ERROR_OVERFLOW );

		/* If we're completed the hashing, we're done.  In addition unlike 
		   CMS, PGP handles authenticated attributes by extending the 
		   hashing of the payload data to cover the additional attributes,
		   so if we're using the PGP format we can't wrap up the hashing
		   yet */
		if( !( envelopeInfoPtr->dataFlags & ENVDATA_HASHACTIONSACTIVE ) || \
			envelopeInfoPtr->type == CRYPT_FORMAT_PGP )
			return( 0 );

		/* We've finished processing everything, complete each hash action if
		   necessary */
		assert( envelopeInfoPtr->actionList != NULL );
		for( hashActionPtr = envelopeInfoPtr->actionList;
			 hashActionPtr != NULL && hashActionPtr->action == ACTION_HASH; 
			 hashActionPtr = hashActionPtr->next )
			{
			status = krnlSendMessage( hashActionPtr->iCryptHandle,
									  IMESSAGE_CTX_HASH, "", 0 );
			if( cryptStatusError( status ) )
				return( status );
			}

		return( 0 );
		}

	/* If we've just completed a segment, begin a new one before we add any
	   data */
	if( envelopeInfoPtr->dataFlags & ENVDATA_SEGMENTCOMPLETE )
		{
		status = beginSegment( envelopeInfoPtr );
		if( cryptStatusError( status ) || \
			envelopeInfoPtr->bufPos >= envelopeInfoPtr->bufSize )
			return( 0 );	/* 0 bytes copied */
		}

	/* Copy over as much as we can fit into the buffer */
	bufPtr = envelopeInfoPtr->buffer + envelopeInfoPtr->bufPos;
	bytesToCopy = envelopeInfoPtr->bufSize - envelopeInfoPtr->bufPos;
	if( bytesToCopy <= 0 )
		{
		/* Safety check */
		assert( NOTREACHED );
		return( CRYPT_ERROR_OVERFLOW );
		}
#ifdef USE_COMPRESSION
	if( envelopeInfoPtr->flags & ENVELOPE_ZSTREAMINITED )
		{
		/* Compress the data into the envelope buffer */
		envelopeInfoPtr->zStream.next_in = ( BYTE * ) buffer;
		envelopeInfoPtr->zStream.avail_in = length;
		envelopeInfoPtr->zStream.next_out = bufPtr;
		envelopeInfoPtr->zStream.avail_out = bytesToCopy;
		status = deflate( &envelopeInfoPtr->zStream, Z_NO_FLUSH );
		if( status != Z_OK )
			return( CRYPT_ERROR );

		/* Adjust the status information based on the data copied into the
		   zStream and flushed from the zStream into the buffer */
		envelopeInfoPtr->bufPos += bytesToCopy - \
								   envelopeInfoPtr->zStream.avail_out;
		bytesToCopy = length - envelopeInfoPtr->zStream.avail_in;

		/* If the buffer is full (there's no more room left for further
		   input) we need to close off the segment */
		if( envelopeInfoPtr->zStream.avail_out <= 0 )
			needCompleteSegment = TRUE;
		}
	else
#endif /* USE_COMPRESSION */
		{
		/* We're not using compression */
		if( bytesToCopy > length )
			bytesToCopy = length;
		memcpy( bufPtr, buffer, bytesToCopy );
		envelopeInfoPtr->bufPos += bytesToCopy;

		/* Hash the data if necessary.  We don't have to check for problems
		   with the context at this point since they'll be detected when we
		   complete the hashing */
		if( envelopeInfoPtr->dataFlags & ENVDATA_HASHACTIONSACTIVE )
			for( hashActionPtr = envelopeInfoPtr->actionList;
				 hashActionPtr != NULL && hashActionPtr->action == ACTION_HASH; 
				 hashActionPtr = hashActionPtr->next )
				krnlSendMessage( hashActionPtr->iCryptHandle,
								 IMESSAGE_CTX_HASH, bufPtr, bytesToCopy );

		/* If the buffer is full (i.e. we've been fed more input data than we
		   could copy into the buffer) we need to close off the segment */
		if( bytesToCopy < length )
			needCompleteSegment = TRUE;
		}
	assert( envelopeInfoPtr->bufPos >= 0 );

	/* Close off the segment if necessary */
	if( needCompleteSegment )
		{
		status = completeSegment( envelopeInfoPtr, FALSE );
		if( cryptStatusError( status ) )
			return( status );
		}

	return( bytesToCopy );
	}

/****************************************************************************
*																			*
*								Copy from Envelope							*
*																			*
****************************************************************************/

/* Copy data from the envelope and begin a new segment in the newly-created
   room.  If called with a zero length value this will create a new segment
   without moving any data.  Returns the number of bytes copied */

static int copyFromEnvelope( ENVELOPE_INFO *envelopeInfoPtr, BYTE *buffer,
							 int length )
	{
	BYTE *bufPtr = envelopeInfoPtr->buffer;
	int remainder;

	assert( isWritePtr( envelopeInfoPtr, sizeof( ENVELOPE_INFO ) ) );
	assert( length >= 0 );
	assert( isWritePtr( buffer, length ) );

	/* Perform a safety check of the envelope state */
	if( envelopeInfoPtr->bufPos < 0 || \
		envelopeInfoPtr->bufPos > envelopeInfoPtr->bufSize )
		{
		assert( NOTREACHED );
		return( CRYPT_ERROR_OVERFLOW );
		}

	/* If the caller wants more data than there is available in the set of
	   completed segments, try to wrap up the next segment to make more data
	   available */
	if( length > envelopeInfoPtr->segmentDataEnd )
		{
		/* Try and complete the segment if necessary.  This may not be
		   possible if we're using a block encryption mode and there isn't
		   enough room at the end of the buffer to encrypt a full block.  If
		   we're generating a detached sig, the data is communicated out-of-
		   band, so there's no segmenting */
		if( !( envelopeInfoPtr->flags & ENVELOPE_DETACHED_SIG ) && \
			!( envelopeInfoPtr->dataFlags & ENVDATA_SEGMENTCOMPLETE ) )
			{
			int status = completeSegment( envelopeInfoPtr, FALSE );
			if( cryptStatusError( status ) )
				return( status );
			}

		/* Return all of the data that we've got */
		length = min( length, envelopeInfoPtr->segmentDataEnd );
		}
	remainder = envelopeInfoPtr->bufPos - length;
	assert( remainder >= 0 && remainder <= envelopeInfoPtr->bufPos );

	/* Copy the data out and move any remaining data down to the start of the
	   buffer  */
	if( length > 0 )
		{
		memcpy( buffer, bufPtr, length );

		/* Move any remaining data down in the buffer */
		if( remainder > 0 )
			memmove( envelopeInfoPtr->buffer, envelopeInfoPtr->buffer + length,
					 remainder );
		envelopeInfoPtr->bufPos = remainder;

		/* Update the segment location information.  Note that the segment 
		   start values track the start position of the last completed segment 
		   and aren't updated until we begin a new segment, so they may go 
		   negative at this point when the data from the last completed 
		   segment is moved past the start of the buffer */
		envelopeInfoPtr->segmentStart -= length;
		envelopeInfoPtr->segmentDataStart -= length;
		envelopeInfoPtr->segmentDataEnd -= length;
		assert( envelopeInfoPtr->segmentDataEnd >= 0 );
		}

	return( length );
	}

/****************************************************************************
*																			*
*							Envelope Access Routines						*
*																			*
****************************************************************************/

void initEnvelopeStreaming( ENVELOPE_INFO *envelopeInfoPtr )
	{
	/* Set the access method pointers */
	envelopeInfoPtr->copyToEnvelopeFunction = copyToEnvelope;
	envelopeInfoPtr->copyFromEnvelopeFunction = copyFromEnvelope;
	}