--- 1/draft-ietf-drip-arch-07.txt 2021-01-21 16:13:09.004780406 -0800 +++ 2/draft-ietf-drip-arch-08.txt 2021-01-21 16:13:09.064781934 -0800 @@ -1,24 +1,24 @@ drip S. Card Internet-Draft A. Wiethuechter Intended status: Informational AX Enterprize -Expires: 3 July 2021 R. Moskowitz +Expires: 25 July 2021 R. Moskowitz HTT Consulting S. Zhao (Editor) Tencent A. Gurtov Linkoeping University - 30 December 2020 + 21 January 2021 Drone Remote Identification Protocol (DRIP) Architecture - draft-ietf-drip-arch-07 + draft-ietf-drip-arch-08 Abstract This document defines an architecture for protocols and services to support Unmanned Aircraft System Remote Identification and tracking (UAS RID), plus RID-related communications, including required architectural building blocks and their interfaces. Status of This Memo @@ -28,87 +28,88 @@ 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 3 July 2021. + This Internet-Draft will expire on 25 July 2021. Copyright Notice - Copyright (c) 2020 IETF Trust and the persons identified as the + Copyright (c) 2021 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 extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Overview UAS Remote ID (RID) and RID Standardization . . 3 1.2. Overview of Types of UAS Remote ID . . . . . . . . . . . 4 - 1.2.1. Network RID . . . . . . . . . . . . . . . . . . . . . 4 - 1.2.2. Broadcast RID . . . . . . . . . . . . . . . . . . . . 5 - 1.3. Overview of USS Interoperability . . . . . . . . . . . . 5 + 1.2.1. Broadcast RID . . . . . . . . . . . . . . . . . . . . 4 + 1.2.2. Network RID . . . . . . . . . . . . . . . . . . . . . 5 + 1.3. Overview of USS Interoperability . . . . . . . . . . . . 6 1.4. Overview of DRIP Architecture . . . . . . . . . . . . . . 6 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 8 3. Definitions and Abbreviations . . . . . . . . . . . . . . . . 8 3.1. Additional Definitions . . . . . . . . . . . . . . . . . 8 3.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 8 3.3. Claims, Assertions, Attestations, and Certificates . . . 9 4. HHIT for UAS Remote ID . . . . . . . . . . . . . . . . . . . 10 4.1. UAS Remote Identifiers Problem Space . . . . . . . . . . 10 4.2. HIT as A Trustworthy UAS Remote ID . . . . . . . . . . . 11 4.3. HHIT for Remote ID Registration and Lookup . . . . . . . 11 - 4.4. HHIT for Remote ID Encryption . . . . . . . . . . . . . . 13 + 4.4. HHIT for Remote ID Encryption . . . . . . . . . . . . . . 12 5. DRIP HHIT RID Registration and Registries . . . . . . . . . . 13 5.1. Public Information Registry . . . . . . . . . . . . . . . 13 5.1.1. Background . . . . . . . . . . . . . . . . . . . . . 13 - 5.1.2. Proposed Approach . . . . . . . . . . . . . . . . . . 14 - 5.2. Private Information Registry . . . . . . . . . . . . . . 14 + 5.1.2. Proposed Approach . . . . . . . . . . . . . . . . . . 13 + 5.2. Private Information Registry . . . . . . . . . . . . . . 13 5.2.1. Background . . . . . . . . . . . . . . . . . . . . . 14 5.2.2. Proposed Approach . . . . . . . . . . . . . . . . . . 14 - 6. Harvesting Broadcast Remote ID messages for UTM Inclusion . . 15 - 6.1. The CS-RID Finder . . . . . . . . . . . . . . . . . . . . 16 - 6.2. The CS-RID SDSP . . . . . . . . . . . . . . . . . . . . . 16 + 6. Harvesting Broadcast Remote ID messages for UTM Inclusion . . 14 + 6.1. The CS-RID Finder . . . . . . . . . . . . . . . . . . . . 15 + 6.2. The CS-RID SDSP . . . . . . . . . . . . . . . . . . . . . 15 7. DRIP Transactions Enabling Trustworthy . . . . . . . . . . . 16 8. Privacy for Broadcast PII . . . . . . . . . . . . . . . . . . 17 - 9. Security Considerations . . . . . . . . . . . . . . . . . . . 18 + 9. Security Considerations . . . . . . . . . . . . . . . . . . . 17 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 18 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 11.1. Normative References . . . . . . . . . . . . . . . . . . 18 - 11.2. Informative References . . . . . . . . . . . . . . . . . 19 + 11.2. Informative References . . . . . . . . . . . . . . . . . 18 Appendix A. Overview of Unmanned Aircraft Systems (UAS) - Traffic . . . . . . . . . . . . . . . . . . . . . . . . . 21 - A.1. Operation Concept . . . . . . . . . . . . . . . . . . . . 21 - A.2. UAS Service Supplier (USS) . . . . . . . . . . . . . . . 22 - A.3. UTM Use Cases for UAS Operations . . . . . . . . . . . . 22 - A.4. Automatic Dependent Surveillance Broadcast (ADS-B) . . . 23 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 + Traffic . . . . . . . . . . . . . . . . . . . . . . . . . 20 + A.1. Operation Concept . . . . . . . . . . . . . . . . . . . . 20 + A.2. UAS Service Supplier (USS) . . . . . . . . . . . . . . . 21 + A.3. UTM Use Cases for UAS Operations . . . . . . . . . . . . 21 + A.4. Automatic Dependent Surveillance Broadcast (ADS-B) . . . 22 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22 1. Introduction - This document describes a natural Internet and MAC-layer broadcast- - based architecture for Unmanned Aircraft System Remote Identification - and tracking (UAS RID), conforming to proposed regulations and - external technical standards, satisfying the requirements listed in - the companion requirements document [I-D.ietf-drip-reqs]. + This document describes an architecture for protocols and services to + support Unmanned Aircraft System Remote Identification and tracking + (UAS RID), plus RID-related communications, conforming to proposed + regulations and external technical standards, satisfying the + requirements listed in the companion requirements document + [I-D.ietf-drip-reqs]. Many considerations (especially safety) dictate that UAS be remotely identifiable. Civil Aviation Authorities (CAAs) worldwide are mandating Unmanned Aircraft Systems (UAS) Remote Identification (RID). CAAs currently (2020) promulgate performance-based regulations that do not specify techniques, but rather cite industry consensus technical standards as acceptable means of compliance. 1.1. Overview UAS Remote ID (RID) and RID Standardization @@ -129,104 +130,107 @@ ASTM [F3411-19] Standard Specification for Remote ID and Tracking. ASTM defines one set of RID information and two means, MAC-layer broadcast and IP-layer network, of communicating it. If a UAS uses both communication methods, generally the same information must provided via both means. The [F3411-19] is cited by FAA in its RID [NPRM] as "one potential means of compliance" to a Remote ID rule. 3GPP - With release 16, 3GPP completed the UAS RID requirement study [TS-22.825] and proposed use cases in the mobile network and the services that can be offered based on RID. Release 17 specification works on enhanced UAS service requirements and provides the protocol and application architecture support which is applicable for both 4G and 5G network. 1.2. Overview of Types of UAS Remote ID -1.2.1. Network RID +1.2.1. Broadcast RID + + A set of RID messages are defined for direct, one-way, broadcast + transmissions from the UA over Bluetooth or Wi-Fi. These are + currently defined as MAC-Layer messages. Internet (or other Wide + Area Network) connectivity is only needed for UAS registry + information lookup by observers using the locally directly received + UAS RID as a key. Broadcast RID should be functionally usable in + situations with no Internet connectivity. + + The Broadcast RID is illustrated in Figure 1 below. + + x x UA + xxxxx + | + | + | app messages directly over + | one-way RF data link (no IP) + | + | + + + x + xxxxx + x + x + x x Observer's device (e.g. smartphone) + x x + + Figure 1 + + With Broadcast RID, an Observer is limited to their radio "visible" + airspace for UAS awareness and information. With Internet queries + using harvested RID, the Observer may gain more information about + those visible UAS. + +1.2.2. Network RID A RID data dictionary and data flow for Network RID are defined in [F3411-19]. This data flow is from a UAS via unspecified means (but at least in part over the Internet) to a Network Remote ID Service - Provider (Net-RID SP). These Net-RID SPs provide this information to - Network Remote ID Display Providers (Net-RID DP). It is the Net-RID - DP that respond to queries from Network Remote ID clients (expected - typically, but not specified exclusively, to be web based) specifying - airspace volumes of interest. Network RID depends upon connectivity, - in several segments, via the Internet, from the UAS to the observer. + Provider (Net-RID SP). These Net-RID SPs provide the RID data + information to Network Remote ID Display Providers (Net-RID DP). It + is the Net-RID DP that responds to queries from Network Remote ID + observers (expected typically, but not specified exclusively, to be + web based) specifying airspace volumes of interest. Network RID + depends upon connectivity, in several segments, via the Internet, + from the UAS to the observer. - The Network RID is illustrated in Figure 1 below: + The Network RID is illustrated in Figure 2 below: x x UA xxxxx ******************** | \ * ------*---+------------+ | \ * / * | NET_RID_SP | | \ * ------------/ +---*--+------------+ | RF \ */ | * | * INTERNET | * +------------+ | /* +---*--| NET_RID_DP | | / * +---*--+------------+ + / * | * x / *****************|*** x xxxxx | xxxxx x +------- x x x x x Operator (GCS) Observer x x x x x x - Figure 1 + Figure 2 Via the direct Radio Frequency (RF) link between the UA and GCS, Command and Control (C2) flows between the GCS to the UA such that either can communicate with the Net-RID SP. For all but the simplest hobby aircraft, position and status flow from the UA to the GCS and on to the Net-RID SP. Thus via the Internet, through three distinct segments, Network RID information flows from the UAS to the Observer. -1.2.2. Broadcast RID - - A set of RID messages are defined for direct, one-way, broadcast - transmissions from the UA over Bluetooth or Wi-Fi. These are - currently defined as MAC-Layer messages. Internet (or other Wide - Area Network) connectivity is only needed for UAS registry - information lookup by Observers using the locally directly received - UAS RID as a key. Broadcast RID should be functionally usable in - situations with no Internet connectivity. - - The Broadcast RID is illustrated in Figure 2 below. - - x x UA - xxxxx - | - | - | app messages directly over - | one-way RF data link (no IP) - | - | - + - x - xxxxx - x - x - x x Observer's device (e.g. smartphone) - x x - - Figure 2 - - With Broadcast RID, an Observer is limited to their radio "visible" - airspace for UAS awareness and information. With Internet queries - using harvested RID, the Observer may gain more information about - those visible UAS. + Informative note: The RF link between UA and GCS is not in + scope of the Network RID. 1.3. Overview of USS Interoperability Each UAS is registered to at least one USS. With Net-RID, there is direct communication between the UAS and its USS. With Broadcast- RID, the UAS Operator has either pre-filed a 4D space volume for USS operational knowledge and/or Observers can be providing information about observed UA to a USS. USS exchange information via a Discovery and Synchronization Service (DSS) so all USS have knowledge about all activities in a 4D airspace. The interactions among observer, UA and @@ -436,38 +440,35 @@ 4.1. UAS Remote Identifiers Problem Space A DRIP UAS ID needs to be "Trustworthy". This means that within the framework of the RID messages, an observer can establish that the RID used does uniquely belong to the UA. That the only way for any other UA to assert this RID would be to steal something from within the UA. The RID is self-generated by the UAS (either UA or GCS) and registered with the USS. - Within the limitations of Broadcast RID, this is extremely - challenging as: - - * An RID can at most be 20 characters. - - * The ASTM Basic RID message (the message containing the RID) is 25 - characters; only 3 characters are currently unused. - - * The ASTM Authentication message, with some changes from [F3411-19] - can carry 224 bytes of payload. + The data communication of using Broadcast RID faces extreme + challenging due to the limitation set by regulations. The ASTM + [F3411-19] defines the Basic RID message which is expected to + contained certain RID data and the Authentication message. The Basic + RID message has a maximum payload of 25 bytes and the maximum size + allocated by ASTM for the RID is 20 bytes and only 3 bytes are left + unused. currently, the authentication maximum payload is defined to + be 224 bytes. Standard approaches like X.509 and PKI will not fit these - constraints, even using the new EdDSA [RFC8032] algorithm. An - example of a technology that will fit within these limitations is an - enhancement of the Host Identity Tag (HIT) of HIPv2 [RFC7401] - introducing hierarchy as defined in HHIT [I-D.ietf-drip-rid]; using - Hierarchical HITs for UAS RID is outlined in HHIT based UAS RID - [I-D.ietf-drip-rid]. As PKI with X.509 is being used in other + constraints, even using the new EdDSA An example of a technology that + will fit within these limitations is an enhancement of the Host + Identity Tag (HIT) of HIPv2 [RFC8032] algorithm.[RFC7401] using + Hierarchical HITs (HHITs) for UAS RID is outlined in HHIT based UAS + RID [I-D.ietf-drip-rid]. As PKI with X.509 is being used in other systems with which UAS RID must interoperate (e.g. the UTM Discovery and Synchronization Service and the UTM InterUSS protocol) mappings between the more flexible but larger X.509 certificates and the HHIT based structures must be devised. By using the EdDSA HHIT suite, self-assertions of the RID can be done in as little as 84 bytes. Third-party assertions can be done in 200 bytes. An observer would need Internet access to validate a self- assertion claim. A third-party assertion can be validated via a small credential cache in a disconnected environment. This third- @@ -490,41 +491,36 @@ of second-preimage resistance. The cryptographically-bound addition of the Hierarchy and a HHIT registration process (e.g. based on Extensible Provisioning Protocol, [RFC5730]) provide complete, global HHIT uniqueness. This is in contrast to general IDs (e.g. a UUID or device serial number) as the subject in an X.509 certificate. 4.3. HHIT for Remote ID Registration and Lookup Remote IDs need a deterministic lookup mechanism that rapidly provides actionable information about the identified UA. The ID - itself needs to be the key into the lookup given the constraints - imposed by some of the broadcast media. This can best be achieved by - an ID registration hierarchy cryptographically embedded within the - ID. - - The original proposal for HITs included a registration hierarchy - scheme. This was dropped during HIP development for lack of a use - case. No similar mechanism is possible within CGAs. It is a rather - straightforward design update to HITs to Hierarchical HITs (HHITs) to - meet the UAS Remote ID use case. + itself needs to be the inquiry input into the lookup given the + constraints imposed by some of the broadcast media. This can best be + achieved by an ID registration hierarchy cryptographically embedded + within the ID. The HHIT needs to consist of a registration hierarchy, the hashing crypto suite information, and the hash of these items along with the underlying public key. Additional information, e.g. an IPv6 prefix, may enhance the HHITs use beyond the basic Remote ID function (e.g. use in HIP, [RFC7401]). A DRIP UAS ID SHOULD be a HHIT. It SHOULD be self-generated by the UAS (either UA or GCS) and MUST be registered with the Private - Information Registry identified in its hierarchy fields. Each UAS ID - HHIT MUST NOT be used more than once, with one exception as follows. + Information Registry (More details in Section 5.2) identified in its + hierarchy fields. Each UAS ID HHIT MUST NOT be used more than once, + with one exception as follows. Each UA MAY be assigned, by its manufacturer, a single HI and derived HHIT encoded as a hardware serial number per [CTA2063A]. Such a static HHIT SHOULD be used only to bind one-time use UAS IDs (other HHITs) to the unique UA. Depending upon implementation, this may leave a HI private key in the possession of the manufacturer (see Security Considerations). Each UA equipped for Broadcast RID MUST be provisioned not only with its HHIT but also with the HI public key from which the HHIT was @@ -746,40 +741,27 @@ * Observers without Internet connectivity MAY use Cra to identify the trust class of the UAS based on known registry vetting. * Observers with Internet connectivity MAY use HHITa to perform lookups in the Public Information Registry and MAY then query the Private Information Registry which MUST enforce AAA policy on Operator PII and other sensitive information 8. Privacy for Broadcast PII - Broadcast RID messages may contain PII. This may be information - about the UA such as its destination or Operator information such as - GCS location. There is no absolute "right" in hiding PII, as there - will be times (e.g., disasters) and places (buffer zones around - airports and sensitive facilities) where policy may mandate all - information be sent as cleartext. Otherwise, the modern general - position (consistent with, e.g., the EU General Data Protection - Regulation) is to hide PII unless otherwise instructed. While some - have argued that a system like that of automobile registration plates - should suffice for UAS, others have argued persuasively that each - generation of new identifiers should take advantage of advancing - technology to protect privacy, to the extent compatible with the - transparency needed to protect safety. - - A viable architecture for PII protection would be symmetric - encryption of the PII using a key known to the UAS and its USS. An - authorized Observer may send the encrypted PII along with the Remote - ID (to their UTM Service Provider) to get the plaintext. - Alternatively, the authorized Observer may receive the key to - directly decrypt all future PII content from the UA. + Broadcast RID messages may contain PII. A viable architecture for + PII protection would be symmetric encryption of the PII using a key + known to the UAS and its USS. An authorized Observer may send the + encrypted PII along with the Remote ID (to their UTM Service + Provider) to get the plaintext. Alternatively, the authorized + Observer may receive the key to directly decrypt all future PII + content from the UA. PII SHOULD protected unless the UAS is informed otherwise. This may come from operational instructions to even permit flying in a space/ time. It may be special instructions at the start or during an operation. PII protection should not be used if the UAS loses connectivity to the USS. The UAS always has the option to abort the operation if PII protection is disallowed. An authorized observer may instruct a UAS via the USS that conditions have changed mandating no PII protection or land the UA (abort the @@ -845,22 +827,22 @@ Commission Delegated Regulation 2019/945 of 12 March 2019 on unmanned aircraft systems and on third-country operators of unmanned aircraft systems", 2019. [F3411-19] ASTM, "Standard Specification for Remote ID and Tracking", 2019. [I-D.ietf-drip-rid] Moskowitz, R., Card, S., Wiethuechter, A., and A. Gurtov, "UAS Remote ID", Work in Progress, Internet-Draft, draft- - ietf-drip-rid-05, 22 December 2020, . + ietf-drip-rid-06, 31 December 2020, . [Implementing] European Union Aviation Safety Agency (EASA), "EU Commission Implementing Regulation 2019/947 of 24 May 2019 on the rules and procedures for the operation of unmanned aircraft", 2019. [LAANC] United States Federal Aviation Administration (FAA), "Low Altitude Authorization and Notification Capability", n.d.,