RFC 1968 (rfc1968) - Page 2 of 11

The PPP Encryption Control Protocol (ECP)

RFC 1968                     PPP Encryption                    June 1996


Table of Contents

      1. Introduction ...........................................  2
      2. Encryption Control Protocol (ECP) ......................  2
          2.1 Sending Encrypted Datagrams .......................  3
      3. Additional Packets .....................................  4
          3.1 Reset-Request and Reset-Ack .......................  5
      4. ECP Configuration Options ..............................  6
          4.1 Proprietary Encryption OUI ........................  7
          4.2 Publicly Available Encryption Types ...............  8
          4.3 Negotiating an Encryption Algorithm ...............  9
      5. Security Considerations ................................ 10

1. Introduction

   In order to establish communications over a PPP link, each end of the
   link must first send LCP packets to configure and test the data link
   during Link Establishment phase.  After the link has been
   established, optional facilities may be negotiated as needed.

   One such facility is data encryption.  A wide variety of encryption
   methods may be negotiated, although typically only one method is used
   in each direction of the link.

   A different encryption algorithm may be negotiated in each direction,
   for speed, cost, memory or other considerations.

2. Encryption Control Protocol (ECP)

   The Encryption Control Protocol (ECP) is responsible for configuring
   and enabling data encryption algorithms on both ends of the point-
   to-point link.

   ECP uses the same packet exchange mechanism as the Link Control
   Protocol (LCP).  ECP packets may not be exchanged until PPP has
   reached the Network-Layer Protocol phase.  ECP packets received
   before this phase is reached should be silently discarded.

   The Encryption Control Protocol is exactly the same as LCP [1] with
   the following exceptions:

      Frame Modifications

         The packet may utilise any modifications to the basic frame
         format which have been negotiated during the Link Establishment
         phase.





Meyer                       Standards Track