I'm looking for a way to synchronize an archive of photos with an archive stored on Google Drive or Dropbox. One of the things that I need to do is to be able to rapidly determine if a given photo has already been uploaded to the remote file system.
The ideal way to do this would be to search by file hash, but looking at the APIs, I can't see an easy way to do that. Dropbox does allow you to walk the user's Dropbox and download metadata (which appears to include an MD5 hash).
Is there a better way?