(6)In order to ensure confidentiality, any type of data exchange between trade repositories and the relevant entities should be carried out through a secure machine-to-machine connection and by using data encryption protocols. To ensure minimum common standards, an SSH File Transfer Protocol (SFTP) should be used between the trade repositories and the entities listed in Article 81(3) of Regulation (EU) No 648/2012. This should not exclude the possibility that trade repositories and the relevant entities may agree amongst themselves to establish secure machine-to-machine connection using an additional, separate channel to the SFTP. Trade repositories should therefore be permitted to continue to use other secure machine-to-machine connections in addition to, but never as a substitute for, the use of SFTP.