Secure BFD Sequence Numbers
draft-ietf-bfd-secure-sequence-numbers-04
Network Working Group M. Jethanandani
Internet-Draft S. Agarwal
Intended status: Standards Track Cisco Systems, Inc
Expires: February 27, 2020 A. Mishra
O3b Networks
A. Saxena
Ciena Corporation
A. Dekok
Network RADIUS SARL
August 26, 2019
Secure BFD Sequence Numbers
draft-ietf-bfd-secure-sequence-numbers-04
Abstract
This document describes a security enhancements for the BFD packet's
sequence number.
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 RFC 2119 [RFC2119].
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
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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 February 27, 2020.
Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Theory of operations . . . . . . . . . . . . . . . . . . . . 2
3. Impact of using a hash . . . . . . . . . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Normative References . . . . . . . . . . . . . . . . . . 5
7.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
BFD [RFC5880] section 6.7 describes the use of monotonically
incrementing 32-bit sequence numbers for use in authentication of BFD
packets. While this method protects against simple replay attacks,
the monotonically incrementing sequence numbers are predictable and
vulnerable to more complex attack vectors. This document proposes
the use of non-monotonically-incrementing sequence numbers in BFD
authentication TLVs to enhance the security of BFD sessions.
Specifically, the document presents a method to generate pseudo-
random sequence numbers on the frame by algorithmically hashing
monotonically increasing sequence numbers. Further security may be
introduced by resetting un-encrypted sequence to a random value when
the 32-bit sequence number rolls-over.
2. Theory of operations
Instead of monotonically increasing the sequence number or even
occasionally monotonically increasing the sequence number, the next
sequence number is generated by computing a hash on what would have
been the next sequence number using a shared key. That computed hash
is then inserted into the sequence number field of the packet. In
case of BFD Authentication [I-D.ietf-bfd-optimizing-authentication],
the sequence number used in computing an authenticated packet would
be this new computed hash. Even though the BFD Authentication
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