S3 and checksums

[ghaya]

Hi, I work at a university where we have our own S3 server. There is a setting in Cyberduck "Verify checksums" on download and upload. I have checked those boxes but I have no idea if it is actually working or which type of checksum is being used to verify the integrity of the files. I was wondering if this might be something that is set up to work with Amazons S3 service but our local S3 (a netapp server) might not automatically be configured to work with Cyberduck and checksums?