Logs:
                block file | bfile (not encrypted) sha1 [| bfile encryption key | encrypted bfile sha1]
                <tab>content file | cfile sha1 | part of parts [| whole file sha1]

def _log_in_sent_log(self, block):
        """ Logs:
                block file | bfile (not encrypted) sha1 [| bfile encryption key | encrypted bfile sha1]
                <tab>content file | cfile sha1 | part of parts [| whole file sha1]
        """
        # FIXME all these should be done by the block itself
        self._sent_log_file.write("\n")
        sent_file_info = block.latest_file_info
        self._sent_log_file.write("|".join((sent_file_info.basename, sent_file_info.sha1)))
        if hasattr(block, 'cipher_key'):
            self._sent_log_file.write("|")
            self._sent_log_file.write("|".join((block.cipher_key, block.ciphered_file_info.sha1)))
        for file_info in block.content_file_infos:
            self._sent_log_file.write("\n\t")
            self._sent_log_file.write("|".join((file_info.path, file_info.sha1)))
            if hasattr(file_info, 'fragment_info'):  # check if it is a fragment
                self._sent_log_file.write("|")
                self._sent_log_file.write("|".join((
                    "%d of %d" % (file_info.fragment_info.fragment_num, file_info.fragment_info.fragments_count),
                    file_info.fragment_info.file_info.sha1)))