DRIP R. Moskowitz
Internet-Draft HTT Consulting
Intended status: Standards Track S. Card
Expires: 28 June 2021 A. Wiethuechter
AX Enterprize
A. Gurtov
Linköping University
25 December 2020
Secure UAS Network RID and C2 Transport
draft-moskowitz-drip-secure-nrid-c2-02
Abstract
This document provides the mechanisms for secure transport of UAS
Network-RemoteID and Command-and-Control messaging. Both HIP and
DTLS based methods are described.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terms and Definitions . . . . . . . . . . . . . . . . . . . . 3
2.1. Requirements Terminology . . . . . . . . . . . . . . . . 3
2.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 3
3. Network RID endpoints . . . . . . . . . . . . . . . . . . . . 3
3.1. N-RID from the UA . . . . . . . . . . . . . . . . . . . . 4
3.2. N-RID from the GCS . . . . . . . . . . . . . . . . . . . 4
3.3. N-RID from the Operator . . . . . . . . . . . . . . . . . 4
3.4. UAS Identity . . . . . . . . . . . . . . . . . . . . . . 4
4. Command and Control . . . . . . . . . . . . . . . . . . . . . 4
5. Secure Transports . . . . . . . . . . . . . . . . . . . . . . 5
5.1. HIPv2 for Secure Transport . . . . . . . . . . . . . . . 5
5.2. DTLS for Secure Transport . . . . . . . . . . . . . . . . 6
5.3. Ciphers for Secure Transport . . . . . . . . . . . . . . 6
5.4. HIP and DTLS contrasted and compared . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1. Normative References . . . . . . . . . . . . . . . . . . 8
9.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
This document defines mechanisms to provide secure transport for the
ASTM Network Remote ID [F3411-19] (N-RID) and UAS Command and Control
(C2) messaging.
A secure transport for C2 is critical for UAS Beyond line of sight
(BLOS) operations.
Two options for secure transport are provided: HIPv2 [RFC7401] and
DTLS [DTLS-1.3-draft]. These options are generally defined and their
applicability is compared and contrasted. It is up to N-RID and C2
to select which is preferred for their situation.
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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.
2.2. Definitions
See [drip-requirements] for common DRIP terms.
B-RID
Broadcast Remote ID. A method of sending RID messages as 1-way
transmissions from the UA to any Observers within radio range.
N-RID
Network Remote ID. A method of sending RID messages via the
Internet connection of the UAS directly to the UTM.
RID
Remote ID. A unique identifier found on all UA to be used in
communication and in regulation of UA operation.
3. Network RID endpoints
The FAA defines the Network Remote ID endpoints as a USS Network
Service Provider (Net-RID SP) and the UAS. Both of these are rather
nebulous items and what they actually are will impact how
communications flow between them.
The Net-RID SP may be provided by the same entity serving as the UAS
Service Provider (USS). This simplifies a number of aspects of the
N-RID communication flow. An Operator is expected to register an
operation with the USS. If this is done via the GCS and the GCS is
the source (directly acting as a gateway), this could set up the
secure connection for N-RID. The Net-RID SP is likely to be stable
in the network, that is its IP address will not change during a
mission. This simplifies maintaining the N-RID communications.
The UAS component in N-RID may be either the UA, GCS, or the
Operator's Internet connected device (e.g. smartphone or tablet). In
all cases, mobility MUST be assumed. That is the IP address of this
end of the N-RID communication will change during an operation. The
N-RID mechanism MUST support this. the UAS Identity for the secure
connection may vary based on the UAS endpoint.
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3.1. N-RID from the UA
Some UA will be equipped with direct Internet access. These UA will
also tend to have multiple radios for their Internet access. Thus
multi-homing with "make before break" behavior is needed. This is on
top of any IP address changes on any of the interfaces while in use.
3.2. N-RID from the GCS
Many UA will lack direct Internet access, but their GCS may be so
connected. There are two sources for the GCS for the RID messages,
both from the UA. These are UA B-RID messages, or content from C2
messages that the GCS converts to RID message format. In either
case, the GCS may be mobile with changing IP addresses. The GCS may
be in a fast moving ground device (delivery van), so it can have as
mobility demanding connection needs as the UA.
3.3. N-RID from the Operator
Many UAS will have no Internet connectivity, but the UA is sending
B-RID messages and the Operator has an Internet Connected device that
is receiving these B-RID messages. The Operator's device can act as
the proxy for these messages, turning them into N-RID messages.
3.4. UAS Identity
The UA MAY use its RID private key if the RID is a HHIT
[drip-uas-rid]. It may use some other Identity, based on the Net-RID
SP policy.
The GCS or Operator smart device may have a copy of the UA
credentials and use them in the connection to the Net-RID SP. In
this case, they are indistinguishable from the UA as seen from the
Net-RID SP. Alternatively, they may use their own credentials with
the Net-RID SP which would need some internal mechanism to tie that
to the UA.
4. Command and Control
Command and Control (C2) connection is between the UA and GCS. Often
this over a direct link radio. Some times, particularly for BLOS, it
is via Internet connections. In either case C2 SHOULD be secure from
eavesdropping and tampering. For design and implementation
consistency it is best to treat the direct link as a local link
Internet connection and use constrained networking compression
standards.
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Both the UA and GCS need to be treated as fully mobile in the IP
networking sense. Either one can have its IP address change and both
could change at the same time (the double jump problem). It is
preferable to use a peer-to-peer (P2P) secure technology like HIPv2
[RFC7401].
Finally UA may also tend to have multiple radios for their C2
communications. Thus multi-homing with "make before break" behavior
is needed. This is on top of any IP address changes on any of the
interfaces while in use.
5. Secure Transports
The raw RID and C2 messages will be wrapped in UDP. These UDP
packets will either be transported in ESP for the HIPv2 approach or
DTLS application messages for DTLS. In both cases header compression
technologies SHOULD be used and negotiated based on policy.
For IPv6 over both WiFi and Bluetooth (or any other radio link),
Robust Header Compression (ROHC) [RFC5795] and/or Generic Header
Compression (6LoWAN-HGC) [RFC7400] can significantly reduce the per
packet transmission cost of IPv6. For Bluetooth, there is also IPv6
over Bluetooth LE [RFC7668] for more guidance.
Local link (direct radio) C2 security is possible with the link's MAC
layer security. Both WiFi and Bluetooth link security can provide
appropriate security, but this would not provide trustworthy multi-
homed security.
5.1. HIPv2 for Secure Transport
HIP has already been used for C2 mobility, managing the ongoing
connectivity over WiFi at start of an operation, switching to LTE
once out of WiFi range, and returning to WiFi connectivity at the end
of the operation. This functionality is especially important for
BLOS. HHITs are already defined for RID, and need only be added to
the GCS via a GCS Registration as part of the UAS to USS registration
to be usedfor C2 HIP.
When the UA is the UAS endpoint for N-RID, and particularly when HIP
is used for C2, HIP for N-RID simplifies protocol use on the UA. The
Net-RID SP endpoint may already support HIP if it is also the HHIT
Registrar. If the UA lacks any IP ability and the RID HHIT
registration was done via the GCS or Operator device, then they may
also be set for using HIP for N-RID.
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Further, double jump and multi-homing support is mandatory for C2
mobility. This is inherent in the HIP design. The HIP address
update can be improved with [hip-fast-mobility].
5.2. DTLS for Secure Transport
DTLS is a good fit for N-RID for any of the possible UAS endpoints.
There are challenges in using it for C2. To use DTLS for C2, the GCS
will need to be the DTLS server. How does it 'push' commands to the
UA? How does it reestablish DTLS security if state is lost? And
finally, how is the double jump scenario handled?
All the above DTLS for C2 probably have solutions. None of them are
inherent in the DTLS design.
5.3. Ciphers for Secure Transport
The cipher choice for either HIP or DTLS depends, in large measure,
on the UAS endpoint. If the endpoint is computationally constrained,
the cipher computations become important. If any of the links are
constrained or expensive, then the over-the-wire cost needs to be
minimized. AES-CCM and AES-GCM are the preferred, modern, AEAD
ciphers.
For ESP with HIP [RFC7402], an additional 4 - 8 bytes can be trimmed
by using the Implicit IV for ESP option [RFC8750].
NIST is working on selecting a new lightweight cipher that may be the
best choice for use on a UA. The Keccak Xoodyak cipher in
[new-crypto] is a good "Green Cipher".
5.4. HIP and DTLS contrasted and compared
This document specifies the use of DTLS 1.3 for its 0-RTT mobility
feature and improved (over 1.2) handshake. DTLS 1.3 is still an IETF
draft, so there is little data available to properly contrast it with
HIPv2. This section will be based on the current DTLS 1.2. The
basic client-server model is unchanged.
The use of DTLS vs HIPv2 (both over UDP, HIP in IPsec ESP BEET mode)
has pros and cons. DTLS is currently at version 1.2 and based on TLS
1.2. It is a more common protocol than HIP, with many different
implementations available for various platforms and languages.
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DTLS implements a client-server model, where the client initiates the
communication. In HIP, two parties are equal and either can be an
Initiator or Responder of the Base Exchange. HIP provides separation
between key management (base exchange) and secure transport (for
example IPsec ESP BEET) while both parts are tightly coupled in DTLS.
DTLS 1.2 still has quite chatty connection establishment taking 3-5
RTTs and 15 packets. HIP connection establishment requires 4 packets
(I1,R1,I2,R2) over 2 RTTs. This is beneficial for constrained
environments of UAs. HIPv2 supports cryptoagility with possibility
to negotiate cryptography mechanisms during the Base Exchange.
Both DTLS and HIP support mobility with a change of IP address.
However, in DTLS only client mobility is well supported, while in HIP
either party can be mobile. The double-jump problem (simultaneous
mobility) is supported in HIP with a help of Rendezvous Server (RVS)
[RFC8004]. HIP can implement secure mobility with IP source address
validation in 2 RTTs, and in 1 RTT with fast mobility extension.
One study comparing DTLS and IPsec-ESP performance concluded that
DTLS is recommended for memory-constrained applications while IPSec-
ESP for battery power-constrained [Vignesh].
6. IANA Considerations
TBD
7. Security Considerations
Designing secure transports is challenging. Where possible, existing
technologies SHOULD be used. Both ESP and DTLS have stood "the test
of time" against many attack scenarios. Their use here for N-RID and
C2 do not represent new uses, but rather variants on existing
depoyments.
The same can be said for both key establishment, using HIPv2 and
DTLS, and the actual cipher choice for per packet encryption and
authentication. N-RID and C2 do not present new challenges, rather
new opportunities to provide communications security using well
researched technologies.
8. Acknowledgments
Stuart Card and Adam Wiethuechter provivded information on their use
of HIP for C2 at the Syracuse NY UAS test corridor. This, in large
measure, was the impetus to develop this document.
9. References
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9.1. 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>.
[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>.
9.2. Informative References
[drip-requirements]
Card, S., Wiethuechter, A., Moskowitz, R., and A. Gurtov,
"Drone Remote Identification Protocol (DRIP)
Requirements", Work in Progress, Internet-Draft, draft-
ietf-drip-reqs-06, 1 November 2020,
<https://tools.ietf.org/html/draft-ietf-drip-reqs-06>.
[drip-uas-rid]
Moskowitz, R., Card, S., Wiethuechter, A., and A. Gurtov,
"UAS Remote ID", Work in Progress, Internet-Draft, draft-
moskowitz-drip-uas-rid-06, 17 August 2020,
<https://tools.ietf.org/html/draft-moskowitz-drip-uas-rid-
06>.
[DTLS-1.3-draft]
Rescorla, E., Tschofenig, H., and N. Modadugu, "The
Datagram Transport Layer Security (DTLS) Protocol Version
1.3", Work in Progress, Internet-Draft, draft-ietf-tls-
dtls13-39, 2 November 2020,
<https://tools.ietf.org/html/draft-ietf-tls-dtls13-39>.
[F3411-19] ASTM International, "Standard Specification for Remote ID
and Tracking", February 2020,
<http://www.astm.org/cgi-bin/resolver.cgi?F3411>.
[hip-fast-mobility]
Moskowitz, R., Card, S., and A. Wiethuechter, "Fast HIP
Host Mobility", Work in Progress, Internet-Draft, draft-
moskowitz-hip-fast-mobility-03, 3 April 2020,
<https://tools.ietf.org/html/draft-moskowitz-hip-fast-
mobility-03>.
[new-crypto]
Moskowitz, R., Card, S., and A. Wiethuechter, "New
Cryptographic Algorithms for HIP", Work in Progress,
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Internet-Draft, draft-moskowitz-hip-new-crypto-06, 2
November 2020, <https://tools.ietf.org/html/draft-
moskowitz-hip-new-crypto-06>.
[RFC5795] Sandlund, K., Pelletier, G., and L-E. Jonsson, "The RObust
Header Compression (ROHC) Framework", RFC 5795,
DOI 10.17487/RFC5795, March 2010,
<https://www.rfc-editor.org/info/rfc5795>.
[RFC7400] Bormann, C., "6LoWPAN-GHC: Generic Header Compression for
IPv6 over Low-Power Wireless Personal Area Networks
(6LoWPANs)", RFC 7400, DOI 10.17487/RFC7400, November
2014, <https://www.rfc-editor.org/info/rfc7400>.
[RFC7401] Moskowitz, R., Ed., Heer, T., Jokela, P., and T.
Henderson, "Host Identity Protocol Version 2 (HIPv2)",
RFC 7401, DOI 10.17487/RFC7401, April 2015,
<https://www.rfc-editor.org/info/rfc7401>.
[RFC7402] Jokela, P., Moskowitz, R., and J. Melen, "Using the
Encapsulating Security Payload (ESP) Transport Format with
the Host Identity Protocol (HIP)", RFC 7402,
DOI 10.17487/RFC7402, April 2015,
<https://www.rfc-editor.org/info/rfc7402>.
[RFC7668] Nieminen, J., Savolainen, T., Isomaki, M., Patil, B.,
Shelby, Z., and C. Gomez, "IPv6 over BLUETOOTH(R) Low
Energy", RFC 7668, DOI 10.17487/RFC7668, October 2015,
<https://www.rfc-editor.org/info/rfc7668>.
[RFC8004] Laganier, J. and L. Eggert, "Host Identity Protocol (HIP)
Rendezvous Extension", RFC 8004, DOI 10.17487/RFC8004,
October 2016, <https://www.rfc-editor.org/info/rfc8004>.
[RFC8750] Migault, D., Guggemos, T., and Y. Nir, "Implicit
Initialization Vector (IV) for Counter-Based Ciphers in
Encapsulating Security Payload (ESP)", RFC 8750,
DOI 10.17487/RFC8750, March 2020,
<https://www.rfc-editor.org/info/rfc8750>.
[Vignesh] Vignesh, K., "Performance analysis of end-to-end DTLS and
IPsec-based communication in IoT environments", Thesis
no. MSEE-2017: 42, 2017, <http://www.diva-
portal.org/smash/get/diva2:1157047/FULLTEXT02>.
Authors' Addresses
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Robert Moskowitz
HTT Consulting
Oak Park, MI 48237
United States of America
Email: rgm@labs.htt-consult.com
Stuart W. Card
AX Enterprize
4947 Commercial Drive
Yorkville, NY 13495
United States of America
Email: stu.card@axenterprize.com
Adam Wiethuechter
AX Enterprize
4947 Commercial Drive
Yorkville, NY 13495
United States of America
Email: adam.wiethuechter@axenterprize.com
Andrei Gurtov
Linköping University
IDA
SE-58183 Linköping
Sweden
Email: gurtov@acm.org
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