As promised (a very long while ago) I moved all the checksum code to a dedicated hiearchy (see https://pharo.fogbugz.com/default.asp?5468). The thing I'm most proud of is the CRC class which implements Ross Williams's "RockSoft" parameterized CRC caculation model (http://www.ross.net/crc/). Currently there are still two plugin primitives (used by the Compression package) which I simply moved to the new Checksum hierarchy. When I originally wrote the CRC class I wasn't aware of NativeBoost. Today I saw that there are two methods NativeBoost offers for crc32 calculations. I don't have time to look in to that but I just wanted to put the idea out there that with the checksum code now all in one place, we might be able to perform all checksum calculations through NB (and get rid of the ZipPlugin :) ). Any thoughts? Cheers, Max