The routine works through the format of the TIFF file based on the Image File Directory (IFD) for the file, calculating CRC-32 for each IFD entry and their associated data (step 502) passing results of the prior CRC-32 as the seed to the next (step 510) until all the IFD entries have been cycled through. (Step 506) [0068] All tags and data areas are processed except the following tags and data are