ADEM Working Group F. E. Linker Internet-Draft ETH Zürich Intended status: Standards Track D. Jackson Expires: 2 March 2024 None D. Basin ETH Zürich 30 August 2023 Serving an Authenticated Digital EMblem over UDP draft-adem-wg-adem-udp-latest Abstract This document describes a mechanism using the User Datagram Protocol (UDP) to distribute _Authenticated Digital EMblem_ (ADEM) tokens [ADEM-CORE]. ADEM tokens encode that an asset is protected under international humanitarian law. About This Document This note is to be removed before publishing as an RFC. Status information for this document may be found at https://datatracker.ietf.org/doc/draft-adem-wg-adem-udp/. Source for this draft and an issue tracker can be found at https://github.com/adem-wg/adem-spec. 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 2 March 2024. Copyright Notice Copyright (c) 2023 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 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. Conventions and Definitions 3. UDP Distribution 4. UDP Parsing 5. Security Considerations 6. IANA Considerations 7. References 7.1. Normative References 7.2. Informative References Acknowledgments Authors' Addresses 1. Introduction The ADEM Core document [ADEM-CORE] specifies how a set of _tokens_, encoded as JSON Web Signatures (JWSs) [RFC7515], can constitute _signs of protection_. Such signs of protection indicate that a digital asset is protected under international humanitarian law (IHL). This document describes a UDP-based distribution method for ADEM tokens, termed ADEM-UDP. 2. Conventions and Definitions 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. UDP Distribution Any digital, network-connected asset MAY distribute sets of ADEM tokens using the UDP protocol. Whenever an asset distributes tokens using UDP, it MUST set the destination port to 60. The data field encodes three elements (in that order): a uint16 _sequence number_, a uint16 stating the number of tokens in this sequence, and the token itself as a sequence of ASCII bytes representing the token's JWS compact serialization. Any UDP packet containing an ADEM token, MUST contain exactly one token. The sequence number identifies sets of related tokens. Therefore, sequence numbers SHOULD NOT repeat per recipient IP and within 300 seconds. ADEM-UDP enabled assets SHOULD send a complete set of tokens allowing for the strongest verification possible (compare [ADEM-CORE], Section 6.1 (./draft-adem-wg-adem-core.html #section-6.1)) whenever a client attempts to connect to the respectively protected asset. ADEM-UDP enabled assets MUST at the same apply rate-limiting mechanisms when sending out tokens to the same clients. Rate limitations SHOULD depend on the number of bytes sent per set of tokens, but assets MUST send a verifier a set of tokens at least every 300 seconds, should the verifier probe the protected asset repeatedly. 4. UDP Parsing When listening on port 60, verifiers can distinguish different sets of tokens using the sequence number. When receiving any token on port 60, verifiers MUST apply a timeout of 300 seconds. That means, they MAY discard tokens from which they were not able to assemble a verifiable sign of protection after 300 seconds. But at the same time, verifiers MUST wait for at least 300 seconds after having probed a protected asset until they may classify this asset as unprotected. Verifiers are RECOMMENDED to start verification procedures as specified in [ADEM-CORE] as soon as they received all internal endorsements belonging to an emblem. Independent endorsements can be verified individually once they are received. 5. Security Considerations 6. IANA Considerations As per the IANA Port Number Registry [REG-PORT], port 60 is currently unassigned. 7. References 7.1. Normative References [ADEM-CORE] Linker, F. E., Jackson, D., and D. Basin, "An Authenticated Digital EMblem - Core Specification", n.d., <./draft-adem-wg-adem-core.html>. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 7.2. Informative References [REG-PORT] "Service Name and Transport Protocol Port Number Registry", n.d., . [RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May 2015, . Acknowledgments TODO acknowledge. Authors' Addresses Felix E. Linker ETH Zürich Email: flinker@inf.ethz.ch Dennis Jackson None Email: ietf@dennis-jackson.uk David Basin ETH Zürich Email: basin@inf.ethz.ch