This section describes the protocols used to delegate access rights from one user to another. In order to obtain a copy of a file a user must interact with FR by means of a protocol. The protocol is named File Repository Transport Protocol (FRTP) [13]. It resembles the Simple Mail Transport Protocol (SMTP) and Network News Transport Protocol (NNTP) protocols in that all commands and responses are encoded in ASCII with short numerical status-codes being returned for each command.
FR requires that users are authenticated and it provides users with the means to establish the authenticity of the server. At connection setup time, a secure channel is established between the user and FR. Certificates can be presented to FR without having to be signed by the delegatee when sent on an authenticated channel. The certificate can also be signed and subsequently sent unencrypted. In the latter case, the file will be returned on the same connection (but not on a secure channel). The latter approach is naturally equivalent with the former except that secrecy is not achieved. FR supports both kinds of interactions mentioned above.