Encryption using KEA and SKIPJACK (RFC2773)
Original Publication Date: 2000-Feb-01
Included in the Prior Art Database: 2019-Feb-10
Internet Society Requests For Comment (RFCs)
R. Housley: AUTHOR [+2]
This document defines a method to encrypt a file transfer using the FTP specification STD 9, RFC 959, "File Transfer Protocol (FTP)", (October
Network Working Group R. Housley Request for Comments: 2773 P. Yee Updates: 959 SPYRUS Category: Experimental W. Nace NSA February 2000
Encryption using KEA and SKIPJACK
Status of this Memo
This memo defines an Experimental Protocol for the Internet community. It does not specify an Internet standard of any kind. Discussion and suggestions for improvement are requested. Distribution of this memo is unlimited.
Copyright (C) The Internet Society (2000). All Rights Reserved.
This document defines a method to encrypt a file transfer using the FTP specification STD 9, RFC 959, "File Transfer Protocol (FTP)", (October 1985)  and RFC 2228, "FTP Security Extensions" (October 1997) . This method will use the Key Exchange Algorithm (KEA) to give mutual authentication and establish the data encryption keys. SKIPJACK is used to encrypt file data and the FTP command channel.
The File Transfer Protocol (FTP) provides no protocol security except for a user authentication password which is transmitted in the clear. In addition, the protocol does not protect the file transfer session beyond the original authentication phase.
The Internet Engineering Task Force (IETF) Common Authentication Technology (CAT) Working Group has proposed security extensions to FTP. These extensions allow the protocol to use more flexible security schemes, and in particular allows for various levels of protection for the FTP command and data connections. This document describes a profile for the FTP Security Extensions by which these mechanisms may be provisioned using the Key Exchange Algorithm (KEA) in conjunction with the SKIPJACK symmetric encryption algorithm.
Housley, et al. Experimental [Page 1]
RFC 2773 Encryption using KEA and SKIPJACK February 2000
FTP Security Extensions  provides:
* user authentication -- augmenting the normal password mechanism;
* server authentication -- normally done in conjunction with user authentication;
* session parameter negotiation -- in particular, encryption keys and attributes;
* command connection protection -- integrity, confidentiality, or both;
* data transfer protection -- same as for command connection protection.
In order to support the above security services, the two FTP entities negotiate a mechanism. This process is open-ended and completes when both entities agree on an acceptable mechanism or when the initiating party (always the client) is unable to suggest an agreeable mechanism. Once the entities agree upon a mechanism, they may commence authentication and/or parameter negotiation.
Authentication and parameter negotiation occur within an unbounded series of exchanges. At the completion of the exchanges, the entities will either be authenticated (unilateral or mutually), and may, additionally, be ready to protect FTP commands and data.
Following the exchanges, the entities negotiate the size of the buffers they will use in protecting the commands and data that follow. This pr...