



TBD                                                    R. Moskowitz, Ed.
Internet-Draft                                            HTT Consulting
Updates: rfc4082 (if approved)                           20 October 2025
Intended status: Standards Track                                        
Expires: 23 April 2026


               TESLA Update for GNSS SBAS Authentication
               draft-moskowitz-tesla-update-gnss-sbas-00

Abstract

   This document updates TESLA [RFC4082] to current cryptographic
   methods for use by the International Civil Aviation Organization
   (ICAO) in their Global Navigation Satellite System (GNSS) Satellite-
   based augmentation system (SBAS) authentication protocol.  The TESLA
   updates are to align it with current best practices.

Status of This Memo

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

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   This Internet-Draft will expire on 23 April 2026.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  SBAS use of TESLA . . . . . . . . . . . . . . . . . . . .   2
   2.  Terms and Definitions . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Requirements Terminology  . . . . . . . . . . . . . . . .   3
   3.  Updates to TESLA  . . . . . . . . . . . . . . . . . . . . . .   3
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   3
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   3
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   3
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   4
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   TESLA [RFC4082] (Timed Efficient Stream Loss-Tolerant Authentication)
   uses the best practices for cryptography when published in 2005.
   This is quite dated, and any modern use of TESLA needs to adjust to
   current algorithms and methods.

   This document focuses on thhe TESLA design targeted by the
   International Civil Aviation Organization (ICAO) in their Global
   Navigation Satellite System (GNSS) Satellite-based augmentation
   system (SBAS) authentication protocol.

   The SBAS authentication protocol is more than a modern TESLA
   implementation.  It uses a very tightly designed PKI and the C509
   certificate encoding [C509-Certificates] to work within the very
   highly constrained SBAS communication link.  The PKI is out-of-scope
   for this document and is described elsewhere within ICAO.

   This document is very much a "work in progress", in that various ICAO
   SBAS documents need to be excised for their technical updates to
   TESLA.  For example, TESLA specifies using a message authentication
   code (MAC) of all communicated data.  SBAS is using HMAC [RFC2104]
   and KMAC [NIST.SP.800-185].

1.1.  SBAS use of TESLA

   The updating of TESLA in SBAS Authentication is outlined in [SBAS
   Authentication].  This document is the public source of changes made
   to TESLA and some of the justifications.







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2.  Terms and Definitions

2.1.  Requirements Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "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.

3.  Updates to TESLA

   TBD - extracted from SBAS documents.

4.  IANA Considerations

   TBD

5.  Security Considerations

   TBD

6.  References

6.1.  Normative References

   [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>.

   [RFC4082]  Perrig, A., Song, D., Canetti, R., Tygar, J. D., and B.
              Briscoe, "Timed Efficient Stream Loss-Tolerant
              Authentication (TESLA): Multicast Source Authentication
              Transform Introduction", RFC 4082, DOI 10.17487/RFC4082,
              June 2005, <https://www.rfc-editor.org/info/rfc4082>.

   [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>.

6.2.  Informative References









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   [C509-Certificates]
              Mattsson, J. P., Selander, G., Raza, S., Höglund, J., and
              M. Furuhed, "CBOR Encoded X.509 Certificates (C509
              Certificates)", Work in Progress, Internet-Draft, draft-
              ietf-cose-cbor-encoded-cert-15, 18 August 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-cose-
              cbor-encoded-cert-15>.

   [NIST.SP.800-185]
              Kelsey, J., Change, S., Perlner, R., and National
              Institute of Standards and Technology, "SHA-3 derived
              functions: cSHAKE, KMAC, TupleHash and ParallelHash",
              DOI 10.6028/nist.sp.800-185, December 2016,
              <https://doi.org/10.6028/nist.sp.800-185>.

   [RFC2104]  Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
              Hashing for Message Authentication", RFC 2104,
              DOI 10.17487/RFC2104, February 1997,
              <https://www.rfc-editor.org/info/rfc2104>.

   [SBAS Authentication]
              Walter, T.W., "Authentication of Satellite-Based
              Augmentation Systems with Over-the-Air Rekeying Schemes",
              <https://navi.ion.org/content/70/3/navi.595>.

Acknowledgments

   This work is in conjunction with the ICAO SBAS Authention Study Group
   members.  This includes, and is not limited to: Jed Dennis (FAA
   Consultant), Abdel Youssouf (Eurocontrol), Timo Warns (Airbus), Todd
   Walter (Stanford) and chair Mikaël Mabilleau (Eurocontrol).

Author's Address

   Robert Moskowitz (editor)
   HTT Consulting
   Oak Park, MI 48237
   United States of America
   Email: rgm@labs.htt-consult.com












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