Skip to main content

Optimizing BFD Authentication
draft-ietf-bfd-optimizing-authentication-21

Document Type Active Internet-Draft (bfd WG)
Authors Mahesh Jethanandani , Ashesh Mishra , Ankur Saxena , Manav Bhatia , Jeffrey Haas
Last updated 2024-10-21
Replaces draft-mahesh-bfd-authentication
RFC stream Internet Engineering Task Force (IETF)
Intended RFC status Proposed Standard
Formats
Yang Validation 0 errors, 0 warnings
Reviews
Additional resources Mailing list discussion
Stream WG state In WG Last Call
Associated WG milestone
Jun 2025
Provide an optimization to BFD authentication to reduce computational demand while still providing desirable security properties.
Document shepherd Reshad Rahman
Shepherd write-up Show Last changed 2020-11-23
IESG IESG state I-D Exists
Consensus boilerplate Unknown
Telechat date (None)
Responsible AD (None)
Send notices to Reshad Rahman <rrahman@cisco.com>
draft-ietf-bfd-optimizing-authentication-21
Network Working Group                                    M. Jethanandani
Internet-Draft                                            Kloud Services
Intended status: Experimental                                  A. Mishra
Expires: 24 April 2025                              Aalyria Technologies
                                                               A. Saxena
                                                       Ciena Corporation
                                                               M. Bhatia
                                                                  Google
                                                                 J. Haas
                                                        Juniper Networks
                                                         21 October 2024

                     Optimizing BFD Authentication
              draft-ietf-bfd-optimizing-authentication-21

Abstract

   This document describes an optimization to BFD Authentication as
   described in Section 6.7 of BFD RFC 5880.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 24 April 2025.

Copyright Notice

   Copyright (c) 2024 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components

Jethanandani, et al.      Expires 24 April 2025                 [Page 1]
Internet-Draft       BFD Authentication Optimization        October 2024

   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
     1.2.  Note to RFC Editor  . . . . . . . . . . . . . . . . . . .   4
     1.3.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Authentication Mode . . . . . . . . . . . . . . . . . . . . .   5
   3.  Signaling Optimized Authentication  . . . . . . . . . . . . .   6
     3.1.  Error Handling  . . . . . . . . . . . . . . . . . . . . .   7
   4.  Optimized Authentication Operations . . . . . . . . . . . . .   7
   5.  Optimizing Authentication YANG Model  . . . . . . . . . . . .   8
     5.1.  Data Model Overview . . . . . . . . . . . . . . . . . . .   8
     5.2.  Tree Diagram  . . . . . . . . . . . . . . . . . . . . . .   8
     5.3.  The YANG Model  . . . . . . . . . . . . . . . . . . . . .   9
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
     6.1.  Auth Type . . . . . . . . . . . . . . . . . . . . . . . .  13
     6.2.  IETF XML Registry . . . . . . . . . . . . . . . . . . . .  13
     6.3.  The YANG Module Names Registry  . . . . . . . . . . . . .  14
     6.4.  Updated IANA Module . . . . . . . . . . . . . . . . . . .  14
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
   8.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  15
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  15
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  17
   Appendix A.  Updated BFD IANA Module  . . . . . . . . . . . . . .  18
   Appendix B.  Examples . . . . . . . . . . . . . . . . . . . . . .  22
     B.1.  Single Hop BFD Configuration  . . . . . . . . . . . . . .  22
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  24

1.  Introduction

   Authenticating every BFD [RFC5880] control packet with MD5
   Message-Digest Algorithm [RFC1321], or Secure Hash Algorithm (SHA-1)
   is a computationally intensive process.  This makes it difficult, if
   not impossible to authenticate every packet - particularly at faster
   rates.  Also, the recent escalating series of attacks on MD5 and
   SHA-1 described in Finding Collisions in the Full SHA-1
   [SHA-1-attack1] and New Collision Search for SHA-1 [SHA-1-attack2]
   raise concerns about their remaining useful lifetime as outlined in
   Updated Security Considerations for the MD5 Message-Digest and the
   HMAC-MD5 Algorithm [RFC6151] and Security Considerations for the
   SHA-0 and SHA-1 Message-Digest Algorithm [RFC6194].  If replaced by
   stronger algorithms, the computational overhead, will make the task
   of authenticating every packet even more difficult to achieve.

Jethanandani, et al.      Expires 24 April 2025                 [Page 2]
Internet-Draft       BFD Authentication Optimization        October 2024

   This document describes an experimental updates to BFD [RFC5880].
   This experiment is intended to provide additional insights into what
   happens when the optimized authentication method defined in this
   document is used.

   This document is classified as Experimental and is not part of the
   IETF Standards Track.  Implementations based on this document should
   not be considered as compliant with BFD [RFC5880] and should not
   assume interoperability with other implementations that conform to
   the existing document.

   This document proposes that BFD control packets that signal a state
   change, a demand mode change (to D bit), a poll sequence change (P or
   F bit change) be categorized as a significant change.  Control
   packets that do not require a poll sequence, such as a change in
   bfd.RequiredMinRxInterval or bfd.RequiredMinTxInterval, are also
   considered as a significant change.  In other words, the contents of
   an Up packet MUST NOT change aside from the authentication section
   without stronger authentication to take advantage of the method
   described in this document.

   In the Up state, most packets that are transmitted and received have
   no state change associated with them.  Limiting authentication to
   packets that affect a BFD session's state allows more sessions to be
   supported with this optimized method of authentication.

   Once the session has reached the Up state, the session can choose a
   less computationally intensive Auth Type.  Currently, this includes:

   *  Meticulous Keyed ISAAC authentication as described in
      [I-D.ietf-bfd-secure-sequence-numbers].  This authentication type
      prevents the attack when the Up packets do not change, because
      only the paired devices know the shared secret, key, and sequence
      number to select the ISAAC result.

   When using optimized methods of authentication, BFD sessions should
   periodically test the session using strong authentication.  Strong
   authentication is tested using a Poll sequence.  To test strong
   authentication, a Poll sequence SHOULD be initiated by the sender
   using the strong authentication Auth Type rather than the chosen
   optimized Auth Type.  If a control packet with the Final (F) bit is
   not received within the Detect Interval, the session has been
   compromised, and should be brought down.  The interval for initiating
   a Poll sequence can be configured depending on the capability of the
   system.

Jethanandani, et al.      Expires 24 April 2025                 [Page 3]
Internet-Draft       BFD Authentication Optimization        October 2024

   Most packets transmitted on a BFD session are BFD Up packets.
   Strongly authenticating a small subset of these packets with a Poll
   sequence as described above, for example every one minute,
   significantly reduces the computational demand for the system while
   maintaining security of the session across the configured strong
   reauthentication interval.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in BCP 14 [RFC2119]
   [RFC8174] when, and only when, they appear in all capitals, as shown
   here.

1.2.  Note to RFC Editor

   This document uses several placeholder values throughout the
   document.  Please replace them as follows and remove this note before
   publication.

   RFC XXXX, where XXXX is the number assigned to this document at the
   time of publication.

   2024-10-21 with the actual date of the publication of this document.

1.3.  Terminology

   The following terms used in this document have been defined in BFD
   [RFC5880].

   *  Auth Type

   *  Detect Multiplier

   *  Detection Time

   The following terms are introduced in this document.

Jethanandani, et al.      Expires 24 April 2025                 [Page 4]
Internet-Draft       BFD Authentication Optimization        October 2024

    +==================+==============================================+
    | Term             | Meaning                                      |
    +==================+==============================================+
    | significant      | State change, a demand mode change (to D     |
    | change           | bit) or a poll sequence change (P or F bit). |
    |                  | Control packets that do not require a poll   |
    |                  | sequence, such as bfd.RequiredMinRxInterval  |
    |                  | bfd.RequiredMinTxInterval, or bfd.DetectMult |
    |                  | are also considered as a significant change. |
    +------------------+----------------------------------------------+
    | configured       | Interval at which BFD control packets are    |
    | strong           | retried with a stronger authentication.      |
    | reauthentication |                                              |
    | interval         |                                              |
    +------------------+----------------------------------------------+

                                  Table 1

2.  Authentication Mode

   The cryptographic authentication mechanisms specified in BFD
   [RFC5880] describes enabling and disabling of authentication as a one
   time operation.  As a security precaution, it mentions that
   authentication state be allowed to change at most once.  Once
   enabled, every packet must have Authentication Bit set and the
   associated Authentication Type appended.  In addition, it states that
   an implementation SHOULD NOT allow the authentication state to be
   changed based on the receipt of a BFD control packet.

   This document proposes that an authentication mode that permits both
   a strong authentication mode and a less expensive "optimized" mode to
   be used within the same BFD session.  This pairing of a strong and an
   optimized mode of authentication is carried in new BFD authentication
   types representing a given authentication type pairing.

   The proposal outlines which BFD control packets are required to be
   strongly authenticated.  A BFD control packet that fails
   authentication is discarded, or a BFD control packet that was
   supposed to be strongly authenticated, but was not; e.g. a
   significant change packet, is discarded.  However, there is no change
   to the state machine for BFD, as the decision of a significant change
   is still decided by how many valid consecutive packets were received.

   In this proposal, the contents of an Up packet MUST NOT change aside
   from the authentication section without stronger authentication.  The
   full procedure is documented in the following sections.

Jethanandani, et al.      Expires 24 April 2025                 [Page 5]
Internet-Draft       BFD Authentication Optimization        October 2024

3.  Signaling Optimized Authentication

   When the Authentication Present (A) bit is set and the Auth Type is a
   type supporting Optimized BFD Authentication (Section 6.1), the Auth
   Type signals a pairing of a strong authentication type and an
   optimized authentication type.  This pairing is advertised in a
   single Auth Type value in order to permit implementations to be aware
   that:

   *  Optimized BFD procedures will be in use.

   *  The pairing of the strong and optimized authentication mechanisms
      will be used for that session.

   *  The current strong or optimized mode will be carried as described
      below:

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Auth Type   |   Auth Len    |  Auth Key ID  |  Optimized    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                   Authentication Specific Data                ~
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Figure 1: Common BFD Authentication Section

   The Meticulous Keyed MD5, Meticulous Keyed SHA-1, and Meticulous
   Keyed ISAAC authentication sections define the fourth octet as
   "Reserved".  This document repurposes the "Reserved" field as the
   "Optimized" field when used for authentication types for optimized
   BFD procedures.

   The values of the Optimized field are:

   1.  When using the strong authentication type for optimized BFD Auth
       Types.

   2.  When using the optimized authentication type for optimized BFD
       Auth Types.

   Authentication Specific Data: When using the strong authentication
   type, the remainder of the authentication section carries that type's
   data.

   For example, for Auth Type "Optimized MD5 Meticulous Keyed ISAAC
   Authentication" (type TBD):

Jethanandani, et al.      Expires 24 April 2025                 [Page 6]
Internet-Draft       BFD Authentication Optimization        October 2024

   When Optimized is 1, the format of the authentication section is the
   same as Section 4.3 of [RFC5880], excepting that Auth Type is still
   TBD and that Reserved is set to 1.

   When Optimized is 2, the format of the authentication section is the
   same as Section 5 of [I-D.ietf-bfd-secure-sequence-numbers],
   excepting that Auth Type is still TBD and that Reserved is set to 2.

3.1.  Error Handling

   If the received BFD Control packet contains an optimized
   authentication type using these procedures and the Optimized field is
   not 1 or 2, then the received packet MUST be discarded.

4.  Optimized Authentication Operations

   As noted in Section 2, when using optimized BFD procedures, strong
   authentication is used in the BFD state machine to bring a BFD
   session to the Up state or to make any change of the BFD parameters
   as carried in the BFD Control packet when in the Up state.

   Once the BFD session has reached the Up state, the BFD Up state MUST
   be signaled to the remote BFD system using the strong authentication
   for at least Detect Mult packets before switching to the optimized
   authentication mode.  This is to permit mechanisms such as Meticulous
   Keyed ISAAC for BFD Authentication
   [I-D.ietf-bfd-secure-sequence-numbers] to be bootstrapped before
   switching to optimized authentication.

   It is RECOMMENDED that when using optimized authentication that
   implementations switch from strong authentication to optimized
   authentication after sending at least Detect Mult packets.  In the
   circumstances where a BFD session successfully reaches the Up state
   with strong authentication, but there are problems with the optimized
   authentication, this will permit the remote system to tear down the
   session as quickly as possible.

   BFD sessions using optimized authentication that succeed in reaching
   the Up state using strong authentication and fail using the optimized
   authentication SHOULD bring the issue to the attention of the
   operator.  Further, implementations MAY wish to throttle session
   restarts.

Jethanandani, et al.      Expires 24 April 2025                 [Page 7]
Internet-Draft       BFD Authentication Optimization        October 2024

   It is further RECOMMENDED that BFD implementations using optimized
   authentication defer notifying their client that the session has
   reached the Up state until it has transitioned to using the optimized
   authentication mode.  In the event where optimized authentication is
   failing in the protocol, this avoids propagating the failed
   transitions to optimized mode to the clients.

5.  Optimizing Authentication YANG Model

5.1.  Data Model Overview

   The YANG 1.1 [RFC7950] model defined in this document augments the
   "ietf-bfd" module to add configuration relevant to the management of
   the feature defined in this document.  In particular, it adds crypto
   algorithms that are described in this model, and in Meticulous Keyed
   ISAAC for BFD Authentication [I-D.ietf-bfd-secure-sequence-numbers].
   It adds a feature statement to enable optimized authentication.
   Finally, it adds an interval value that specifies how often the BFD
   session should be re-authenticated once it is in the Up state, and
   the key chain that should be used in the Up state.

5.2.  Tree Diagram

   The tree diagram for the YANG modules defined in this document use
   annotations defined in YANG Tree Diagrams.  [RFC8340].

   module: ietf-bfd-opt-auth

     augment /rt:routing/rt:control-plane-protocols
               /rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh
               /bfd-ip-sh:sessions/bfd-ip-sh:session
               /bfd-ip-sh:authentication:
       +--rw reauth-interval?   uint32
     augment /rt:routing/rt:control-plane-protocols
               /rt:control-plane-protocol/bfd:bfd/bfd-ip-mh:ip-mh
               /bfd-ip-mh:session-groups/bfd-ip-mh:session-group
               /bfd-ip-mh:authentication:
       +--rw reauth-interval?   uint32
     augment /rt:routing/rt:control-plane-protocols
               /rt:control-plane-protocol/bfd:bfd/bfd-lag:lag
               /bfd-lag:sessions/bfd-lag:session/bfd-lag:authentication:
       +--rw reauth-interval?   uint32
     augment /rt:routing/rt:control-plane-protocols
               /rt:control-plane-protocol/bfd:bfd/bfd-mpls:mpls
               /bfd-mpls:session-groups/bfd-mpls:session-group
               /bfd-mpls:authentication:
       +--rw reauth-interval?   uint32

Jethanandani, et al.      Expires 24 April 2025                 [Page 8]
Internet-Draft       BFD Authentication Optimization        October 2024

5.3.  The YANG Model

   This YANG module imports YANG Key Chain [RFC8177], A YANG Data Model
   for Routing Management (NMDA version) [RFC8349], and YANG Data Model
   for Bidirectional Forwarding Detection (BFD) [RFC9314].

   Implementations supporting the optimization procedures defined in
   this document enable optimization by using one of the newly defined
   key-chain crypto-algorithms defined in this YANG module.

   <CODE BEGINS> file "ietf-bfd-opt-auth@2024-10-21.yang"
   module ietf-bfd-opt-auth {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-bfd-opt-auth";
     prefix "bfdoa";

     import ietf-routing {
       prefix "rt";
       reference
         "RFC 8349: A YANG Data Model for Routing Management
          (NMDA version)";
     }

     import ietf-bfd {
       prefix bfd;
       reference
         "RFC 9314: YANG Data Model for Bidirectional
         Forwarding Detection (BFD).";
     }

     import ietf-bfd-ip-sh {
       prefix bfd-ip-sh;
       reference
         "RFC 9314: YANG Data Model for Bidirectional
         Forwarding Detection (BFD).";
     }

     import ietf-bfd-ip-mh {
       prefix bfd-ip-mh;
       reference
         "RFC 9314: YANG Data Model for Bidirectional
         Forwarding Detection (BFD).";
     }

     import ietf-bfd-lag {
       prefix bfd-lag;
       reference
         "RFC 9314: YANG Data Model for Bidirectional

Jethanandani, et al.      Expires 24 April 2025                 [Page 9]
Internet-Draft       BFD Authentication Optimization        October 2024

         Forwarding Detection (BFD).";
     }

     import ietf-bfd-mpls {
       prefix bfd-mpls;
       reference
         "RFC 9314: YANG Data Model for Bidirectional
         Forwarding Detection (BFD).";
     }

     import ietf-key-chain {
       prefix key-chain;
       reference
         "RFC 8177: YANG Data Model for Key Chains.";
     }

     organization
       "IETF BFD Working Group";

     contact
       "WG Web:   <http://tools.ietf.org/wg/bfd>
        WG List:  <rtg-bfd@ietf.org>

        Authors: Mahesh Jethanandani (mjethanandani@gmail.com)
                 Ashesh Mishra (mishra.ashesh@gmail.com)
                 Ankur Saxena (ankurpsaxena@gmail.com)
                 Manav Bhatia (mnvbhatia@google.com).";

     description
       "This YANG module augments the base BFD YANG model to add
        attributes related to BFD Optimized Authentication.

        Copyright (c) 2024 IETF Trust and the persons identified as
        authors of the code.  All rights reserved.

        Redistribution and use in source and binary forms, with or
        without modification, is permitted pursuant to, and subject to
        the license terms contained in, the Revised BSD License set
        forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (https://trustee.ietf.org/license-info).

        This version of this YANG module is part of RFC XXXX
        (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
        for full legal notices.

        The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL

Jethanandani, et al.      Expires 24 April 2025                [Page 10]
Internet-Draft       BFD Authentication Optimization        October 2024

        NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
        'MAY', and 'OPTIONAL' in this document are to be interpreted as
        described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
        they appear in all capitals, as shown here.";

     revision "2024-10-21" {
       description
         "Initial Version.";
       reference
         "RFC XXXX: Optimizing BFD Authentication.";
     }

     feature optimized-auth {
       description
         "When enabled, this implementation supports optimized
          authentication as described in this document.";
     }

     identity optimized-md5-meticulous-keyed-isaac {
       base key-chain:crypto-algorithm;
       description
         "BFD Optimized Authentication using Meticulous Keyed MD5 as the
          strong authentication and Meticulous Keyed ISAAC Keyed as the
          'optimized' authentication.";
       reference
         "RFC XXXX: Meticulous Keyed ISAAC for BFD Authentication.
          I-D.ietf-bfd-secure-sequence-numbers:
            Meticulous Keyed ISAAC for BFD Authentication.";
     }

     identity optimized-sha1-meticulous-keyed-isaac {
       base key-chain:crypto-algorithm;
       description
         "BFD Optimized Authentication using Meticulous Keyed SHA-1 as
         the strong authentication and Meticulous Keyed ISAAC Keyed as
         the 'optimized' authentication.";
       reference
         "I-D.ietf-bfd-optimizing-authentication:
            Meticulous Keyed ISAAC for BFD Authentication.
          I-D.ietf-bfd-secure-sequence-numbers:
            Meticulous Keyed ISAAC for BFD Authentication.";
     }

     grouping bfd-opt-auth-config {
       description
         "Grouping for BFD Optimized Authentication Parameters.";
       leaf reauth-interval {
         type uint32;

Jethanandani, et al.      Expires 24 April 2025                [Page 11]
Internet-Draft       BFD Authentication Optimization        October 2024

         units "seconds";
         default "60";
         description
           "Interval of time after which strong authentication
            should be utilized to prevent an on-path-attacker attack.
            Default is 1 minute.

            A value of zero means that we do not do periodic
            re-authorization using strong authentication.

            This value SHOULD have jitter applied to it to avoid
            self-synchronization during expensive authentication
            operations.";
       }
     }

     augment "/rt:routing/rt:control-plane-protocols" +
             "/rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh" +
             "/bfd-ip-sh:sessions/bfd-ip-sh:session" +
             "/bfd-ip-sh:authentication" {
       uses bfd-opt-auth-config;

       description
         "Augment the 'authentication' container for single hop BFD
          module to add attributes related to BFD optimized
          authentication.";
     }

     augment "/rt:routing/rt:control-plane-protocols/" +
             "rt:control-plane-protocol/bfd:bfd/bfd-ip-mh:ip-mh/" +
             "bfd-ip-mh:session-groups/bfd-ip-mh:session-group/" +
             "bfd-ip-mh:authentication" {
       uses bfd-opt-auth-config;

       description
         "Augment the 'authentication' container for multi-hop BFD
          module to add attributes related to BFD optimized
          authentication.";
     }

     augment "/rt:routing/rt:control-plane-protocols/" +
             "rt:control-plane-protocol/bfd:bfd/bfd-lag:lag/" +
             "bfd-lag:sessions/bfd-lag:session/" +
             "bfd-lag:authentication" {
       uses bfd-opt-auth-config;

       description
         "Augment the 'authentication' container for BFD over LAG

Jethanandani, et al.      Expires 24 April 2025                [Page 12]
Internet-Draft       BFD Authentication Optimization        October 2024

          module to add attributes related to BFD optimized
          authentication.";
     }

     augment "/rt:routing/rt:control-plane-protocols/" +
             "rt:control-plane-protocol/bfd:bfd/bfd-mpls:mpls/" +
             "bfd-mpls:session-groups/bfd-mpls:session-group/" +
             "bfd-mpls:authentication" {
       uses bfd-opt-auth-config;

       description
         "Augment the 'authentication' container for BFD over MPLS
          module to add attributes related to BFD optimized
          authentication.";
     }
   }
   <CODE ENDS>

6.  IANA Considerations

   This documents requests the assignment of two new authentication
   types, one URI, one YANG model, and an update to an existing IANA
   YANG model.

6.1.  Auth Type

   This document requests an update to the registry titled "BFD
   Authentication Types".  IANA is requested to assign two new BFD
   AuthType:

   *  Optimized MD5 Meticulous Keyed ISAAC Authentication
      [I-D.ietf-bfd-secure-sequence-numbers] (Part
      meticulous-keyed-isaac-authentication), with a suggested value of
      7.

   *  Optimized SHA-1 Meticulous Keyed ISAAC Authentication
      [I-D.ietf-bfd-secure-sequence-numbers] (Part
      meticulous-keyed-isaac-authentication), with a suggested value of
      8.

6.2.  IETF XML Registry

   This document registers one URIs in the "ns" subregistry of the "IETF
   XML" registry [RFC3688].  Following the format in [RFC3688], the
   following registration is requested:

Jethanandani, et al.      Expires 24 April 2025                [Page 13]
Internet-Draft       BFD Authentication Optimization        October 2024

   URI: urn:ietf:params:xml:ns:yang:ietf-bfd-opt-auth
   Registrant Contact: The IESG
   XML: N/A, the requested URI is an XML namespace.

6.3.  The YANG Module Names Registry

   This document registers one YANG modules in the "YANG Module Names"
   registry [RFC6020].  Following the format in [RFC6020], the following
   registrations are requested:

   name:         ietf-bfd-opt-auth
   namespace:    urn:ietf:params:xml:ns:yang:ietf-bfd-opt-auth
   prefix:       bfdoa
   reference:    RFC XXXX

6.4.  Updated IANA Module

   This document also requests an update to an existing IANA YANG module
   described in Updated BFD IANA Module (Appendix A).

7.  Security Considerations

   The YANG module specified in this document defines a schema for data
   that is designed to be accessed via network management protocols such
   as NETCONF [RFC6241] or RESTCONF [RFC8040].  The lowest NETCONF layer
   is the secure transport layer, and the mandatory-to-implement secure
   transport is Secure Shell (SSH) [RFC6242].  The lowest RESTCONF layer
   is HTTPS, and the mandatory-to-implement secure transport is TLS
   [RFC8446].  The NETCONF Access Control Model (NACM) [RFC8341]
   provides the means to restrict access for particular NETCONF or
   RESTCONF users to a preconfigured subset of all available NETCONF or
   RESTCONF protocol operations and content.

   There are a number of data nodes defined in this YANG module that are
   writable/creatable/deletable (i.e., config true, which is the
   default).  These data nodes may be considered sensitive or vulnerable
   in some network environments.  Write operations (e.g., edit-config)
   to these data nodes without proper protection can have a negative
   effect on network operations.  Some of the subtrees and data nodes
   and their sensitivity/vulnerability are described here.

Jethanandani, et al.      Expires 24 April 2025                [Page 14]
Internet-Draft       BFD Authentication Optimization        October 2024

   *  'reauth-interval' specifies the interval in Up state, after which
      a strong authentication SHOULD be performed to prevent a Person-
      In-The-Middle (PITM) attack.  If this interval is set very low,
      the utility of these optimization procedures is lessened.  If this
      interval is set very high, attacks detected by the strong
      authentication mechanisms may happen overly late.

   Some of the readable data nodes in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control read access (e.g., via get, get-config, or
   notification) to these data nodes.

   There are no read-only data nodes defined in this model.

   Some of the RPC operations in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control access to these operations.

   There are no RPC operations defined in this model.

   The approach described in this document enhances the ability to
   authenticate a BFD session by taking away the onerous requirement
   that every BFD control packet be authenticated.  By authenticating
   packets that affect the state of the session, the security of the BFD
   session is maintained.  In this mode, packets that are a significant
   change but are not authenticated, are dropped by the system.
   Therefore, a malicious user that tries to inject a non-authenticated
   packet; e.g. with a Down state to take a session down will fail.
   That combined with the proposal of using sequence number defined in
   Meticulous Keyed ISAAC for BFD Authentication
   [I-D.ietf-bfd-secure-sequence-numbers] further enhances the security
   of BFD sessions.

8.  Contributors

   The authors of this document would like to acknowledge Reshad Rahman
   as a contributor to this document.

9.  References

9.1.  Normative References

Jethanandani, et al.      Expires 24 April 2025                [Page 15]
Internet-Draft       BFD Authentication Optimization        October 2024

   [I-D.ietf-bfd-secure-sequence-numbers]
              DeKok, A., Jethanandani, M., Agarwal, S., Mishra, A., and
              A. Saxena, "Meticulous Keyed ISAAC for BFD
              Authentication", Work in Progress, Internet-Draft, draft-
              ietf-bfd-secure-sequence-numbers-17, 7 October 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-bfd-
              secure-sequence-numbers-17>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/info/rfc3688>.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
              <https://www.rfc-editor.org/info/rfc5880>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/info/rfc6020>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
              <https://www.rfc-editor.org/info/rfc6242>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/info/rfc8040>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

Jethanandani, et al.      Expires 24 April 2025                [Page 16]
Internet-Draft       BFD Authentication Optimization        October 2024

   [RFC8177]  Lindem, A., Ed., Qu, Y., Yeung, D., Chen, I., and J.
              Zhang, "YANG Data Model for Key Chains", RFC 8177,
              DOI 10.17487/RFC8177, June 2017,
              <https://www.rfc-editor.org/info/rfc8177>.

   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/info/rfc8341>.

   [RFC8349]  Lhotka, L., Lindem, A., and Y. Qu, "A YANG Data Model for
              Routing Management (NMDA Version)", RFC 8349,
              DOI 10.17487/RFC8349, March 2018,
              <https://www.rfc-editor.org/info/rfc8349>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/info/rfc8446>.

   [RFC9127]  Rahman, R., Ed., Zheng, L., Ed., Jethanandani, M., Ed.,
              Pallagatti, S., and G. Mirsky, "YANG Data Model for
              Bidirectional Forwarding Detection (BFD)", RFC 9127,
              DOI 10.17487/RFC9127, October 2021,
              <https://www.rfc-editor.org/info/rfc9127>.

   [RFC9314]  Jethanandani, M., Ed., Rahman, R., Ed., Zheng, L., Ed.,
              Pallagatti, S., and G. Mirsky, "YANG Data Model for
              Bidirectional Forwarding Detection (BFD)", RFC 9314,
              DOI 10.17487/RFC9314, September 2022,
              <https://www.rfc-editor.org/info/rfc9314>.

9.2.  Informative References

   [I-D.ietf-bfd-stability]
              Mishra, A., Jethanandani, M., Saxena, A., Pallagatti, S.,
              and M. Chen, "BFD Stability", Work in Progress, Internet-
              Draft, draft-ietf-bfd-stability-16, 7 October 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-bfd-
              stability-16>.

   [RFC1321]  Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
              DOI 10.17487/RFC1321, April 1992,
              <https://www.rfc-editor.org/info/rfc1321>.

   [RFC6151]  Turner, S. and L. Chen, "Updated Security Considerations
              for the MD5 Message-Digest and the HMAC-MD5 Algorithms",
              RFC 6151, DOI 10.17487/RFC6151, March 2011,
              <https://www.rfc-editor.org/info/rfc6151>.

Jethanandani, et al.      Expires 24 April 2025                [Page 17]
Internet-Draft       BFD Authentication Optimization        October 2024

   [RFC6194]  Polk, T., Chen, L., Turner, S., and P. Hoffman, "Security
              Considerations for the SHA-0 and SHA-1 Message-Digest
              Algorithms", RFC 6194, DOI 10.17487/RFC6194, March 2011,
              <https://www.rfc-editor.org/info/rfc6194>.

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/info/rfc8340>.

   [SHA-1-attack1]
              Wang, X., Yin, Y., and H. Yu, "Finding Collisions in the
              Full SHA-1", 2005.

   [SHA-1-attack2]
              Wang, X., Yao, A., and F. Yao, "New Collision Search for
              SHA-1", 2005.

Appendix A.  Updated BFD IANA Module

   This section carries the updated IANA BFD Module, iana-bfd-types.yang
   module, first defined in YANG Data Model for Bidirectional Forward
   Detection (BFD) [RFC9127].  The updated module carries three new
   authentication type enum definitions, 'null' with a suggested value
   of 6, and 'optimized-md5-meticulous-keyed-isaac' with a suggested
   value of 7, and 'optimized-sha1-meticulous-keyed-isaac' with a
   suggested value of 8.  Note, the null enum type is used by BFD
   Stability [I-D.ietf-bfd-stability] only, but is being defined here to
   make sure changes to this YANG module do not cause a conflict.  This
   module should replace the version that currently exists in the IANA
   registry.

   <CODE BEGINS> file "iana-bfd-types@2024-10-21.yang"
   module iana-bfd-types {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:iana-bfd-types";
     prefix iana-bfd-types;

     organization
       "IANA";
     contact
       "Internet Assigned Numbers Authority

        Postal: ICANN
                12025 Waterfront Drive, Suite 300
                Los Angeles, CA 90094-2536
                United States of America
        Tel:    +1 310 301 5800
        <mailto:iana@iana.org>";

Jethanandani, et al.      Expires 24 April 2025                [Page 18]
Internet-Draft       BFD Authentication Optimization        October 2024

     description
       "This module defines YANG data types for IANA-registered
        BFD parameters.

        This YANG module is maintained by IANA and reflects the
        'BFD Diagnostic Codes' and 'BFD Authentication Types'
        registries.

        Copyright (c) 2021 IETF Trust and the persons identified as
        authors of the code.  All rights reserved.

        Redistribution and use in source and binary forms, with or
        without modification, is permitted pursuant to, and subject to
        the license terms contained in, the Simplified BSD License set
        forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (https://trustee.ietf.org/license-info).

        The initial version of this YANG module is part of RFC 9127;
        see the RFC itself for full legal notices.";
     reference
       "RFC 9127: YANG Data Model for Bidirectional Forwarding
        Detection (BFD)";

     revision 2024-10-21 {
       description
         "Add NULL and Meticulous ISAAC authentication type.";
       reference
         "RFC XXXX: Optimizing BFD Authentication,
          I-D.ietf-bfd-stability: BFD Stability.";
     }

     revision 2021-10-21 {
       description
         "Initial revision.";
       reference
         "RFC 9127: YANG Data Model for Bidirectional Forwarding
          Detection (BFD)";
     }

     /*
      * Type definitions
      */

     typedef diagnostic {
       type enumeration {
         enum none {
           value 0;

Jethanandani, et al.      Expires 24 April 2025                [Page 19]
Internet-Draft       BFD Authentication Optimization        October 2024

           description
             "No Diagnostic.";
         }
         enum control-expiry {
           value 1;
           description
             "Control Detection Time Expired.";
         }
         enum echo-failed {
           value 2;
           description
             "Echo Function Failed.";
         }
         enum neighbor-down {
           value 3;
           description
             "Neighbor Signaled Session Down.";
         }
         enum forwarding-reset {
           value 4;
           description
             "Forwarding Plane Reset.";
         }
         enum path-down {
           value 5;
           description
             "Path Down.";
         }
         enum concatenated-path-down {
           value 6;
           description
             "Concatenated Path Down.";
         }
         enum admin-down {
           value 7;
           description
             "Administratively Down.";
         }
         enum reverse-concatenated-path-down {
           value 8;
           description
             "Reverse Concatenated Path Down.";
         }
         enum mis-connectivity-defect {
           value 9;
           description
             "Mis-connectivity defect.";
           reference

Jethanandani, et al.      Expires 24 April 2025                [Page 20]
Internet-Draft       BFD Authentication Optimization        October 2024

             "RFC 5880: Bidirectional Forwarding Detection (BFD)
              RFC 6428: Proactive Connectivity Verification, Continuity
              Check, and Remote Defect Indication for the MPLS
              Transport Profile";
         }
       }
       description
         "BFD diagnostic codes as defined in RFC 5880.  Values are
          maintained in the 'BFD Diagnostic Codes' IANA registry.
          Range is 0 to 31.";
       reference
         "RFC 5880: Bidirectional Forwarding Detection (BFD)";
     }

     typedef auth-type {
       type enumeration {
         enum reserved {
           value 0;
           description
             "Reserved.";
         }
         enum simple-password {
           value 1;
           description
             "Simple Password.";
         }
         enum keyed-md5 {
           value 2;
           description
             "Keyed MD5.";
         }
         enum meticulous-keyed-md5 {
           value 3;
           description
             "Meticulous Keyed MD5.";
         }
         enum keyed-sha1 {
           value 4;
           description
             "Keyed SHA1.";
         }
         enum meticulous-keyed-sha1 {
           value 5;
           description
             "Meticulous Keyed SHA1.";
         }
         enum null {
           value 6;

Jethanandani, et al.      Expires 24 April 2025                [Page 21]
Internet-Draft       BFD Authentication Optimization        October 2024

           description
             "NULL Auth. Used for stability measurement.";
         }
         enum optimized-md5-meticulous-keyed-isaac {
           value 7;
           description
             "BFD Optimized Authentication using Meticulous Keyed
              MD5 as the strong authentication and Meticulous Keyed
              ISAAC as the 'optimized' authentication.";
         }
         enum optimized-sha1-meticulous-keyed-isaac {
           value 8;
           description
             "BFD Optimized Authentication using Meticulous Keyed
              SHA-1 as the strong authentication and Meticulous Keyed
              ISAAC as the 'optimized' authentication.";
         }
       }
       description
         "BFD authentication type as defined in RFC 5880.  Values are
          maintained in the 'BFD Authentication Types' IANA registry.
          Range is 0 to 255.";
       reference
         "RFC 5880: Bidirectional Forwarding Detection (BFD),
          I-D.ietf-bfd-optimizing-authentication:
              Optimizing BFD Authentication,
          I-D.ietf-bfd-stability: BFD Stability.";
     }
   }
   <CODE ENDS>

Appendix B.  Examples

   This section tries to show some examples in how the model can be
   configured.

B.1.  Single Hop BFD Configuration

   This example demonstrates how a Single Hop BFD session can be
   configured for optimized authentication.

   =============== NOTE: '\' line wrapping per RFC 8792 ===============

   <?xml version="1.0" encoding="UTF-8"?>
   <key-chains
       xmlns="urn:ietf:params:xml:ns:yang:ietf-key-chain">
     <key-chain>
       <name>bfd-auth-config</name>

Jethanandani, et al.      Expires 24 April 2025                [Page 22]
Internet-Draft       BFD Authentication Optimization        October 2024

       <description>"An example for BFD Optimized Auth configuration."\
   </description>
       <key>
         <key-id>55</key-id>
         <lifetime>
           <send-lifetime>
             <start-date-time>2017-01-01T00:00:00Z</start-date-time>
             <end-date-time>2017-02-01T00:00:00Z</end-date-time>
           </send-lifetime>
           <accept-lifetime>
             <start-date-time>2016-12-31T23:59:55Z</start-date-time>
             <end-date-time>2017-02-01T00:00:05Z</end-date-time>
           </accept-lifetime>
         </lifetime>
         <crypto-algorithm xmlns:opt-auth=
         "urn:ietf:params:xml:ns:yang:ietf-bfd-opt-auth">opt-auth:opti\
   mized-sha1-meticulous-keyed-isaac</crypto-algorithm>
         <key-string>
           <keystring>testvector</keystring>
         </key-string>
       </key>
     </key-chain>
   </key-chains>
   <interfaces
       xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"
       xmlns:if-type="urn:ietf:params:xml:ns:yang:iana-if-type">
     <interface>
       <name>eth0</name>
       <type>if-type:ethernetCsmacd</type>
     </interface>
   </interfaces>
   <routing
       xmlns="urn:ietf:params:xml:ns:yang:ietf-routing"
       xmlns:bfd-types="urn:ietf:params:xml:ns:yang:ietf-bfd-types"
       xmlns:iana-bfd-types="urn:ietf:params:xml:ns:yang:iana-bfd-type\
   s"
       xmlns:opt-auth="urn:ietf:params:xml:ns:yang:ietf-bfd-opt-auth">
     <control-plane-protocols>
       <control-plane-protocol>
         <type>bfd-types:bfdv1</type>
         <name>name:BFD</name>
         <bfd xmlns="urn:ietf:params:xml:ns:yang:ietf-bfd">
           <ip-sh xmlns="urn:ietf:params:xml:ns:yang:ietf-bfd-ip-sh">
             <sessions>
               <session>
                 <interface>eth0</interface>
                 <dest-addr>2001:db8:0:113::101</dest-addr>
                 <desired-min-tx-interval>10000</desired-min-tx-interv\

Jethanandani, et al.      Expires 24 April 2025                [Page 23]
Internet-Draft       BFD Authentication Optimization        October 2024

   al>
                 <required-min-rx-interval>
                   10000
                 </required-min-rx-interval>
                 <authentication>
                   <key-chain>bfd-auth-config</key-chain>
                   <opt-auth:reauth-interval>30</opt-auth:reauth-inter\
   val>
                 </authentication>
               </session>
             </sessions>
           </ip-sh>
         </bfd>
       </control-plane-protocol>
     </control-plane-protocols>
   </routing>

Authors' Addresses

   Mahesh Jethanandani
   Kloud Services
   United States of America
   Email: mjethanandani@gmail.com

   Ashesh Mishra
   Aalyria Technologies
   Email: ashesh@aalyria.com

   Ankur Saxena
   Ciena Corporation
   3939 N 1st Street
   San Jose, CA 95134
   United States of America
   Email: ankurpsaxena@gmail.com

   Manav Bhatia
   Google
   Doddanekkundi
   Bangalore 560048
   India
   Email: mnvbhatia@google.com

Jethanandani, et al.      Expires 24 April 2025                [Page 24]
Internet-Draft       BFD Authentication Optimization        October 2024

   Jeffrey Haas
   Juniper Networks
   Email: jhaas@pfrc.org

Jethanandani, et al.      Expires 24 April 2025                [Page 25]