Archived Forum Post

Index of archived forum posts


32 bit vs 64 bit compression

Dec 19 '14 at 08:58

I am using the Chilkat Zip class to submit files to a government agency. They are telling me now that they do not accept files that are compressed using 64-bit encoding. They only accept 32-bit encoding. I do not specify the encoding anywhere in the code. Is there a way to force '32-bit encoding' when creating a zip file?

A simplified version of my code:

      theZipFile.NewZip(mstrFilePathList(0) & theZipName)
      theZipFile.AppendOneFileOrDir(mstrFilePathList(intInd) & mstrFileNameList(intInd))


I don't understand what they mean by "32-bit encoding". A zip archive has a file format, not an "encoding". If a file within the .zip is larger than 4GB, or if the total size of the .zip is more than 4GB, then the ZIP64 file format is automatically used by Chilkat. There is no other choice -- you can't go bigger than 4GB with 32-bits. Chilkat should not be using the ZIP64 format unless it is required because of size.


If the resultant .zip is small,then send it to me at I can quickly have a look in a hex editor to see if the ZIP64 records exist at the very end of the .zip.