Somebody posting as
thewhizkid complained to the comp.compression newsgroup that he just couldn't figure out how to do a CRC calculation. He got a couple of good pointers here, including one to the zlib code, and another including a bit of Java that could do the job. I'll add a pointer to my ancient-but-still-cogent article from DDJ,
'>http://marknelson.us/articles/crcman/crcman.htm">File Verification Using CRC to the mix. Between the three choices, I hope the poster was able to get a handle on the mysterious CRC.