Hi, There are multiple filetransfer XEPs like e.g. XEP-0385 / XEP-0447 / XEP-0396 They define a hash element, but its not clear to me if the hash is after encryption or before, if the file should be transferred encrypted. If it is after encryption, the hash can only be used in edge cases for caching purposes (look up if we have this file already) because encryption keys change with each file transfer hence the hash of the encrypted file would change. Regards Philipp