Secure file transfer over TCP/IP

With the spread of internetworks able to link LANs, and the availability of network hardware to monitor network traffic, the need to add additional security to traditional network utilities is becoming imperative. The development of security extensions to the FTP file transfer utility/protocol in the TCP/IP communications suite in order to provide authentication of the user and encryption of the files transferred is described. Specific security issues, including some alternatives for providing these security extensions, are given, and the final choice is explained. Initial trials of the implementation are presented. These show that on a single LAN link there is a performance penalty in providing encryption, but that over a wide area internetwork this is masked by the network delays