Network Working Group A. Brotman Internet-Draft Comcast, Inc Intended status: Standards Track S. Farrell Expires: January 9, 2020 Trinity College Dublin July 8, 2019 Related Domains By DNS draft-brotman-rdbd-02 Abstract This document outlines a mechanism by which a DNS domain can publicly document the existence or absence of a relationship with a different domain, called "Related Domains By DNS", or "RDBD". 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 January 9, 2020. Copyright Notice Copyright (c) 2019 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. Brotman & Farrell Expires January 9, 2020 [Page 1] Internet-Draft RDBD July 2019 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 2. New Resource Record Types . . . . . . . . . . . . . . . . . . 4 2.1. RDBDKEY Resource Record Definition . . . . . . . . . . . 4 2.2. RDBD Resource Record Definition . . . . . . . . . . . . . 5 3. Directionality and Cardinality . . . . . . . . . . . . . . . 7 4. Required Signature Algorithms . . . . . . . . . . . . . . . . 7 5. Validation . . . . . . . . . . . . . . . . . . . . . . . . . 7 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 6.1. Efficiacy of signatures . . . . . . . . . . . . . . . . . 8 6.2. DNSSEC . . . . . . . . . . . . . . . . . . . . . . . . . 8 6.3. Lookup Loops . . . . . . . . . . . . . . . . . . . . . . 8 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 9. Informative References . . . . . . . . . . . . . . . . . . . 9 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 10 A.1. Unsigned Examples . . . . . . . . . . . . . . . . . . . . 10 A.2. RSA-signed Example . . . . . . . . . . . . . . . . . . . 11 A.3. Ed25519-signed Example . . . . . . . . . . . . . . . . . 13 Appendix B. Ed25519 Signing Code . . . . . . . . . . . . . . . . 15 Appendix C. Changes and Open Issues . . . . . . . . . . . . . . 16 C.1. Changes from -01 to -02 . . . . . . . . . . . . . . . . . 17 C.2. Changes from -00 to -01 . . . . . . . . . . . . . . . . . 17 C.3. Open Issues . . . . . . . . . . . . . . . . . . . . . . . 17 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 1. Introduction [[Discussion of this draft is taking place on the dbound@ietf.org mailing list. There's a github repo for this draft at - issues and PRs are welcome there.]] Determining relationships between registered domains can be one of the more difficult investigations on the Internet. It is typical to see something such as "example.com" and "dept-example.com" and be unsure if there is an actual relationship between those two domains, or if one might be an attacker attempting to impersonate the other. In some cases, anecdotal evidence from the DNS or WHOIS/RDAP may be sufficient. However, service providers of various kinds may err on the side of caution and treat one of the domains as untrustworthy or abusive because it is not clear that the two domains are in fact related. This specification provides a way for one domain to explicitly document a relationship with another, utilizing DNS records. Brotman & Farrell Expires January 9, 2020 [Page 2] Internet-Draft RDBD July 2019 Possible use cases include: o where a company has websites in different languages, and would like to correlate their ownership more easily, consider "example.de" and "example.ie" registered by regional offices of the same company; o following an acquisition, a domain holder might want to indicate that example.net is now related to example.com in order to make a later migration easier; o when doing Internet surveys, we should be able to provide more accurate results if we have information as to which domains are related. Similarly, a domain may wish to declare that no relationship exists with some other domain, for example "good.example" may want to declare that it is not associated with "g00d.example" if the latter is currently being used in some cousin-domain style attack. In such cases, it is more likely that there can be a larger list of names (compared to the "positive" use-cases) for which there is a desire to disavow a relationship. It is not a goal of this specification to provide a high-level of assurance as to whether or not two domains are definitely related, nor to provide fine-grained detail about the kind of relationship that may exist between domains. Using "Related Domains By DNS", or "RDBD", it is possible to declare that two domains are related, or to disavow such a relationship. We include an optional digital signature mechanism that can somewhat improve the level of assurance with which an RDBD declaration can be handled. This mechanism is partly modelled on how DKIM [RFC6376] handles public keys and signatures - a public key is hosted at the relating-domain (e.g., "example.com") and a reference from the related-domain (e.g., "dept-example.com") contains a signature (verifiable with the "example.com" public key) over the text representation ('A-label') of the two domain names (plus a couple of other inputs). RDBD is intended to declare or disavow a relationship between registered domains, not individual hostnames. That is to say that the relationship should exist between "example.com" and "dept- example.com", not "foo.example.com" and "bar.dept-example.com" (where those latter two are hosts). Brotman & Farrell Expires January 9, 2020 [Page 3] Internet-Draft RDBD July 2019 There already exists Vouch By Reference (VBR) [RFC5518], however this only applies to email. RDBD could be a more general purpose solution that could be applied to other use cases, as well as for SMTP transactions. This document describes the various options, how to create records, and the method of validation, if the option to use digital signatures is chosen. 1.1. 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 [RFC2119]. The following terms are used throughout this document: o Relating-domain: this refers to the domain that is declarating a relationship exists. (This was called the "parent/primary" in -00). o Related-domain: This refers to the domain that is referenced by the relating-domain, such as "dept-example.com". (This was called the "secondary" in -00.) 2. New Resource Record Types We define two new RRTYPES, an optional one for the relating-domain (RDBDKEY) to store a public key for when signatures are in use and one for use in related-domains (RDBD). 2.1. RDBDKEY Resource Record Definition The RDBDKEY record is published at the apex of the relating-domain zone. The wire and presentation format of the RDBDKEY resource record is identical to the DNSKEY record. [RFC4034] [[All going well, at some point we'll be able to say...]] IANA has allocated RR code TBD for the RDBDKEY resource record via Expert Review. The RDBDKEY RR uses the same registries as DNSKEY for its fields. (This follows the precedent set for CDNSKEY in [RFC7344].) Brotman & Farrell Expires January 9, 2020 [Page 4] Internet-Draft RDBD July 2019 No special processing is performed by authoritative servers or by resolvers, when serving or resolving. For all practical purposes, RDBDKEY is a regular RR type. The flags field of RDBDKEY records MUST be zero. [[Is that correct/ ok? I've no idea really:-)]] There can be multiple occurrences of the RDBDKEY resource record in the same zone 2.2. RDBD Resource Record Definition To declare a relationship exists an RDBD resource record is published at the apex of the related-domain zone. To disavow a relationship an RDBD resource record is published at the apex of the relating-domain zone. [[All going well, at some point we'll be able to say...]] IANA has allocated RR code TBD for the RDBD resource record via Expert Review. The RDBD RR is class independent. The RDBD RR has no special Time to Live (TTL) requirements. There can be multiple occurrences of the RDBD resource record in the same zone. The wire format for an RDBD RDATA consists of a two octet rdbd-tag, the relating-domain name(s), and the optional signature fields which are: a two-octet key-tag, a one-octet signature algorithm, and the digital signature bits. 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | rdbd-tag | / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / / relating-domain name(s) / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+| | key-tag | sig-alg | / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / / signature / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ We define two possible values for the rdbd-tag in this specification, later specifications can define new rdbd-tag values: Brotman & Farrell Expires January 9, 2020 [Page 5] Internet-Draft RDBD July 2019 o 0: states that no relationship exists between the domains o 1: states that some relationship exists between the domains The relating-domain name(s) field contains either a single domain name, or an HTTPS URL. In the latter case, successfully de- referencing that URL results in a JSON object that contains the list of domain names, such as is shown in the figure below. [ "example.com", "example.net", "foo.example" ] If an optional signature is included, the sig-alg field MUST contain the signature algorithm used, with the same values used as would be used in an RRSIG. The key-tag MUST match the RDBDKEY RR value for the corresponding public key. If the optional signature is omitted, then the presentation form of the key-tag, sig-alg and signature fields MAY be omitted. If not omitted then the sig-alg and key-tag fields MUST be zero and the signature field MUST be a an empty string. [[Is that the right way to have optional fields in RRs? Not sure.]] The input to signing ("to-be-signed" data) is the concatenation of the following linefeed-separated (where linefeed has the value '0x0a') lines: relating= related= rdbd-tag= key-tag= sig-alg= The relating-domain and related-domain values MUST be the 'A-label' representation of these names. The trailing "." representing the DNS root MUST NOT be included in the to-be-signed data, so a relating-domain value above might be "example.com" but "example.com." MUST NOT be used as input to signing. Brotman & Farrell Expires January 9, 2020 [Page 6] Internet-Draft RDBD July 2019 A linefeed MUST be included after the "sig-alg" value in the last line. [[Presentation syntax and to-be-signed details are very liable to change.]] See the examples in the Appendix for further details. 3. Directionality and Cardinality RDBD relationships are uni-directional. If bi-directional relationships exist, then both domains can publish RDBD RRs and optionally sign those. If one domain has relationships with many others, then the relevant RDBD RRs (and RDBDKEY RRs) can be published to represent those or one RDBD RR can contain an HTTPS URL at which one can provide a list of names. 4. Required Signature Algorithms Consumers of RDBD RRs MAY support signature verification. They MUST be able to parse/process unsigned or signed RDBD RRs even if they cannot cryptographically verify signatures. Implementations producing RDBD RRs SHOULD support optional signing of those and production of RDBDKEY RRs. Implementations of this specification that support signing or verifying signatures MUST support use of RSA with SHA256 (sig-alg==8) with at least 2048 bit RSA keys. [RFC5702] RSA keys SHOULD use a 2048 bit or longer modulus. Implementations of this specification that support signing or verifying signatures SHOULD support use of Ed25519 (sig-alg==15). [RFC8080][RFC8032] 5. Validation A validated signature is solely meant to be additional evidence that the relevant domains are related, or that one disavows such a relationship. The existence or disavowal of a relationship does not by itself mean that data or services from any domain should be considered as more or less trustworthy. Brotman & Farrell Expires January 9, 2020 [Page 7] Internet-Draft RDBD July 2019 6. Security Considerations 6.1. Efficiacy of signatures The optional signature mechanism defined here offers no protection against an active attack if both the RDBD and RDBDKEY values are accessed via an untrusted path. If the RDBDKEY value has been cached, or is otherwise known via some sufficiently secure mechanism, then the RDBD signature does confirm that the holder of the private key (presumably the relating-domain) considered that the relationship, or lack thereof, with a related- domain was real at some point in time. 6.2. DNSSEC RDBD does not require DNSSEC. Without DNSSEC it is possible for an attacker to falsify DNS query responses for someone investigating a relationship. Conversely, an attacker could delete the response that would normally demonstrate the relationship, causing the investigating party to believe there is no link between the two domains. An attacker could also replay an old RDBD value that is actually no longer published in the DNS by the related-domain. Deploying signed records with DNSSEC should allow for detection of these kinds of attack. If the relating-domain has DNSSEC deployed, but the related-domain does not, then the optional signature can (in a sense) extend the DNSSEC chain to cover the RDBD RR in the related-domain's zone. If both domains have DNSSEC deployed, and if the relating-domain public key has been cached, then the the signature mechanism provides additional protection against active attacks involving a parent of one of the domains. Such attacks may in any case be less likely and detectable in many scenarios as they would be generic attacks against DNSSEC-signing (e.g. if a regisgtry injected a bogus DS for a relating-domain into the registry's signed zone). If the public key from the relevant RDNDKEY RRs is read from the DNS at the same time as a related RDBD RR, then the signature mechanism provided here may provide litle additional value over and above DNSSEC. 6.3. Lookup Loops It's conceivable that an attacker could create a loop of relationships, such as a.com->b.com->c.com->a.com or similar. This could cause a resource issue for any automated system. A system SHOULD only perform three lookups from the first domain Brotman & Farrell Expires January 9, 2020 [Page 8] Internet-Draft RDBD July 2019 (a.com->b.com->c.com->d.com). The related and relating-domains SHOULD attempt to keep links direct and so that only the fewest number of lookups are needed, but it is understood this may not always be possible. 7. IANA Considerations This document introduces two new DNS RR types, RDBD and RDBDKEY. [[Codepoints for those are not yet allocated by IANA, nor have codepoints been requested so far.]] [[New rdbd-tag value handling wll need to be defined if we keep that field. Maybe something like: 0-255: RFC required; 256-1023: reserved; 1024-2047: Private use; 2048-65535: FCFS.]] 8. Acknowledgements Thanks to all who commented on this on the dbound and other lists, in particular to the following who provided comments that caused us to change the draft: Bob Harold, John Levine, Andrew Sullivan, Suzanne Woolf, and Paul Wouters. (We're not implying any of these fine folks actually like this draft btw, but we did change it because of their comments:-) Apologies to anyone we missed, just let us know and we'll add your name here. 9. Informative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "Resource Records for the DNS Security Extensions", RFC 4034, DOI 10.17487/RFC4034, March 2005, . [RFC5518] Hoffman, P., Levine, J., and A. Hathcock, "Vouch By Reference", RFC 5518, DOI 10.17487/RFC5518, April 2009, . [RFC5702] Jansen, J., "Use of SHA-2 Algorithms with RSA in DNSKEY and RRSIG Resource Records for DNSSEC", RFC 5702, DOI 10.17487/RFC5702, October 2009, . Brotman & Farrell Expires January 9, 2020 [Page 9] Internet-Draft RDBD July 2019 [RFC6376] Crocker, D., Ed., Hansen, T., Ed., and M. Kucherawy, Ed., "DomainKeys Identified Mail (DKIM) Signatures", STD 76, RFC 6376, DOI 10.17487/RFC6376, September 2011, . [RFC7344] Kumari, W., Gudmundsson, O., and G. Barwood, "Automating DNSSEC Delegation Trust Maintenance", RFC 7344, DOI 10.17487/RFC7344, September 2014, . [RFC8032] Josefsson, S. and I. Liusvaara, "Edwards-Curve Digital Signature Algorithm (EdDSA)", RFC 8032, DOI 10.17487/RFC8032, January 2017, . [RFC8080] Sury, O. and R. Edmonds, "Edwards-Curve Digital Security Algorithm (EdDSA) for DNSSEC", RFC 8080, DOI 10.17487/RFC8080, February 2017, . Appendix A. Examples This appendix provides examples of RDBD-related values. The following names and other values are used in these examples. o Relating domain: my.example o Related domain: my-way.example o Unrelated domain: my-bad.example o URL for other related domains: o URL for other unrelaed domains: The github repo has a script in sample/mk_samples.sh that generated this appendix. A.1. Unsigned Examples Brotman & Farrell Expires January 9, 2020 [Page 10] Internet-Draft RDBD July 2019 ;ZONE FILE FRAGMENT STARTS ; assertion that my-way.example claims to be related ; to my.example my-way.example. 3600 IN RDBD 1 my.example. ; assertion that my-way.example claims not to be ; related to my-bad.example my-way.example. 3600 IN RDBD 0 my-bad.example. ; assertion that my-way.example claims to be related ; to whatever is at https://example.com/related-names my-way.example. 3600 IN RDBD 1 https://example.com/related-names ; assertion that my-way.example claims not to be ; related to whatever is at https://example.com/related-names my-way.example. 3600 IN RDBD 0 https://example.com/unrelateds ;ZONE FILE FRAGMENT ENDS A.2. RSA-signed Example # BASH SNIPPET STARTS # HOWTO generate RSA key pair $ openssl genrsa -out rsa.private 2048 Generating RSA private key, 2048 bit long modulus (2 primes) .....................+++++ .....................+++++ e is 65537 (0x010001) writing RSA key $ openssl rsa -in rsa.private -out rsa.public -pubout \ -outform PEM $ cat rsa.private -----BEGIN RSA PRIVATE KEY----- MIIEowIBAAKCAQEA8qpGa2i6O76MdGiFVYGgd6UDYfUNl4qHpXfzmrqawUqb8JHM 5m8hjLTbKDGRpZJA5m9sQlaM41hQxpAPuW3mJXYvVOiqxtRCBlVTvUCR+Gkah7LU FT54U8PT+ciF2or2ArL7O1LIT1PnEL0AZsbM6FwYLsRE8RX89PqeL9N/U4xJ7jQq SRK88bnRRFs+W7F+iQuA5erHfIZHftq+yzRG8rtgTN7HvTOewkDa2XS2Tn/z0tRV wNUX4Mi4e/DaEZU0u3kn7HqL0hyBXz/EEHUq9+57BURUT/ZQ41ORGgJ/4+tv2Gp8 mp1ydOJaAhzgqky2zGBL1RS+mBFCio9dXBIJywIDAQABAoIBAQDwE7ITtcr6LKy8 xmOTkul1NVZBZbYKxU0qUaA65n8Q2IWq3jR/jlb85DkmbNQRoL6AvJ+4ifRdQBS6 PfCwnZ/iVCjDsmSyzXB835I3XFiOET3kHvJgCiv1g3qGVvLGolB9nyGbMW1nvjSO hM6O4AP9po9uRVOHyR84J3K1EmOX/PgmITPel61CEe+IdYwX3K3w1Mmm9C3ZSitx rx8gpWHknpAG9Z+DA+f406TFTFtuTQe6xCDjKl0/uUGsT62UQqEiw00wekm8e+2b rDdtqu61Lqq1aakhtGlozXIT7ED+oobp6cAnM1QbV09z7zZevXl95yrXt9xZ3odS HNcHnMCRAoGBAP6N00vMmplk76OOJ738Twf6fsaL+zkwNmL74Rv85LJn96p6xQUm wJdMsa7HoD7LwuxhJkhDbdTiq+oV+Mc4J+FAe5xRK5vD7wVmPNWtUcvwdTZXnpNr Brotman & Farrell Expires January 9, 2020 [Page 11] Internet-Draft RDBD July 2019 6fU28PqL76feU22G/V2mthgKOXPvYehcteAJAEGbLwQoo1Q7qZa7Q9i/AoGBAPQL KSqcOzGHJ57iYN+HbN0cqXpBburA7dZstl6WiwQO0U4+KsJ3eyyuUE0Mz6epXeQD Ry1W8yoH9ypfLDEP3YwP3wp7dqISyGAzsRospGyGJ0tHkQ3orW+/6PgSl9W2aJV2 LqyfOPutrjfIRUkgALMq8cTRxR1xpx0HpVfOMCX1AoGAJi9SPfGgU1hf1lIRxh8e H91EvTXsZqTD089i8lbaW6Ta8xjdiytIAqo/kS9i62iXgewE2Rw8Uo36KfBH1GKp INISeN14RDJ9HXs7rvYD6irU+mTkZcrvWph2R69MMQtZynlQcob6k9qcybZkIn4d zlCrWCwWPnJ2JcGZbAIFaHMCgYBXIdD95LABu/a6dKsPxANrYrtj6g7XBDEmuMPY O7nApiW24N1Vd2FkD4yeJe/SNddO/JiiKIRDQnrOBxL5JWf9hQEmdfRiY4BlUK9v 3/aIxNEswI2awLODzao5QDIz3J+0lXCOs36d5WHpiriqJiH51mBh3F+bZqO66qrv EbABLQKBgDUhcsEyIMI6oygKO/L+iVOZM+ao+64TtKxqUmgHU+gBgvdkY8h9GvxY kL7L1hBOB9bAyP8ObU18R5CMbQgO7PITACRoU+uYIiQ67UREDKjBRtoDcgK0JrRX kqy4v6LuuFCpS5OJKQL6rKfk2XNSjDD1ZwLuBZjHQDdc/gnn7XRx -----END RSA PRIVATE KEY----- $ cat rsa.public -----BEGIN PUBLIC KEY----- MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA8qpGa2i6O76MdGiFVYGg d6UDYfUNl4qHpXfzmrqawUqb8JHM5m8hjLTbKDGRpZJA5m9sQlaM41hQxpAPuW3m JXYvVOiqxtRCBlVTvUCR+Gkah7LUFT54U8PT+ciF2or2ArL7O1LIT1PnEL0AZsbM 6FwYLsRE8RX89PqeL9N/U4xJ7jQqSRK88bnRRFs+W7F+iQuA5erHfIZHftq+yzRG 8rtgTN7HvTOewkDa2XS2Tn/z0tRVwNUX4Mi4e/DaEZU0u3kn7HqL0hyBXz/EEHUq 9+57BURUT/ZQ41ORGgJ/4+tv2Gp8mp1ydOJaAhzgqky2zGBL1RS+mBFCio9dXBIJ ywIDAQAB -----END PUBLIC KEY----- # To-be-signed data for RSA $ cat to-be-signed-8.txt relating=my.example related=my-way.example rdbd-tag=1 key-tag=38501 sig-alg=8 # Sign that $ openssl dgst -sha256 -sign rsa.private -out rsa.sig \ to-be-signed-8.txt # Hexdump of signature $ hexdump rsa.sig 0000000 8664 bd57 8cbf a8e1 9182 1b5f a4fc 5eb9 0000010 49b4 fe21 f1c7 8097 ed90 44a5 bcb1 543c 0000020 f784 c190 e1d9 2f2b 18ca d3c2 640f 3823 0000030 7f8a e446 d0eb bd14 6077 0597 6015 a82b 0000040 42d7 8677 b1a3 37fa a1e8 8109 07ec ff62 0000050 16b8 3895 66de d992 dc4d ed99 9ec3 0a62 0000060 6a07 3baa 45f2 d528 1e83 a147 60ce 9b25 0000070 a967 4ba0 3fb5 98db 5ff3 b070 058b 4d8f 0000080 f198 6c1f e6b6 7a6c 1e8c ad42 237f 5440 0000090 7856 caac f96c f87d e79c 4dc5 b833 bc03 00000a0 c52e 5603 46a7 59b5 9fe3 fccd 04ee e908 00000b0 71e7 21f8 47ad fea8 40bf 14a5 9e6b b3d4 00000c0 c61a 5b96 c559 3491 4dfa 91a0 4c0b f3ff Brotman & Farrell Expires January 9, 2020 [Page 12] Internet-Draft RDBD July 2019 00000d0 e460 484c 7e49 5368 85e3 16be fe6b 809a 00000e0 117d c2cb be19 c5ba 7594 2f60 16ad 1132 00000f0 f978 6ca1 5448 180f 8ca7 e73d 1137 7064 0000100 # BASH SNIPPET ENDS ; ZONE FILE FRAGMENT STARTS ; The RDBDKEY RR for my.example is... my.example. 3600 IN RDBDKEY 0 3 8 ( LS0tLS1CRUdJTiBQVUJMSUMgS0VZLS0tLS0KTUlJQklqQU5C Z2txaGtpRzl3MEJBUUVGQUFPQ0FROEFNSUlCQ2dLQ0FRRUE4 cXBHYTJpNk83Nk1kR2lGVllHZwpkNlVEWWZVTmw0cUhwWGZ6 bXJxYXdVcWI4SkhNNW04aGpMVGJLREdScFpKQTVtOXNRbGFN NDFoUXhwQVB1VzNtCkpYWXZWT2lxeHRSQ0JsVlR2VUNSK0dr YWg3TFVGVDU0VThQVCtjaUYyb3IyQXJMN08xTElUMVBuRUww QVpzYk0KNkZ3WUxzUkU4Ulg4OVBxZUw5Ti9VNHhKN2pRcVNS Szg4Ym5SUkZzK1c3RitpUXVBNWVySGZJWkhmdHEreXpSRwo4 cnRnVE43SHZUT2V3a0RhMlhTMlRuL3owdFJWd05VWDRNaTRl L0RhRVpVMHUza243SHFMMGh5Qlh6L0VFSFVxCjkrNTdCVVJV VC9aUTQxT1JHZ0ovNCt0djJHcDhtcDF5ZE9KYUFoemdxa3ky ekdCTDFSUyttQkZDaW85ZFhCSUoKeXdJREFRQUIKLS0tLS1F TkQgUFVCTElDIEtFWS0tLS0tCg== ) ; The RDBD RR to be published by my-way.example is... my-way.example. 3600 IN RDBD 1 my.example 38501 8 ( ZIZXvb+M4aiCkV8b/KS5XrRJIf7H8ZeAkO2lRLG8PFSE95DB 2eErL8oYwtMPZCM4in9G5OvQFL13YJcFFWArqNdCd4ajsfo3 6KEJgewHYv+4FpU43maS2U3cme3DnmIKB2qqO/JFKNWDHkeh zmAlm2epoEu1P9uY819wsIsFj02Y8R9stuZseoweQq1/I0BU Vnisymz5ffic58VNM7gDvC7FA1anRrVZ45/N/O4ECOnncfgh rUeo/r9ApRRrntSzGsaWW1nFkTT6TaCRC0z/82DkTEhJfmhT 44W+Fmv+moB9EcvCGb66xZR1YC+tFjIRePmhbEhUDxinjD3n NxFkcA== ) ; ZONE FILE FRAGMENT ENDS A.3. Ed25519-signed Example Brotman & Farrell Expires January 9, 2020 [Page 13] Internet-Draft RDBD July 2019 # BASH SNIPPET STARTS # HOWTO generate an Ed25519 key pair... $ ./ed25519-signer.py -s rdbd-example0001rdbd-example0002 \ -r my.example -d my-way.example private:b'726462642d6578616d706c6530303031726462642d6578616d 706c6530303032' public:b'353fc31e1168c91f0af65d6c26fd441fb7df9671a23a746bb3e c86be8d35b648' b64pubkey: NT/DHhFoyR8K9l1sJv1EH7fflnGiOnRrs+yGvo01tkg= keyid: 35988 to-be-signed:|relating=my.example related=my-way.example rdbd-tag=1 key-tag=35988 sig-alg=15 | sig:b'64bc444ce759fb9435fe9c1875eb241c4ec6d0995cd8138a372782 32fc8e79f53cb8f88059f6040054c61be8cfd73fd44521f73994628fc7c3 0135fa929ab00f' # hex dump of Ed25519 private $ hexdump ed25519.priv 0000000 6472 6462 652d 6178 706d 656c 3030 3130 0000010 6472 6462 652d 6178 706d 656c 3030 3230 0000020 # hex dump of Ed25519 public $ hexdump ed25519.pub 0000000 3f35 1ec3 6811 1fc9 f60a 6c5d fd26 1f44 0000010 dfb7 7196 3aa2 6b74 ecb3 be86 358d 48b6 0000020 # hex dump of Ed25519 signature $ hexdump ed25519.sig 0000000 bc64 4c44 59e7 94fb fe35 189c eb75 1c24 0000010 c64e 99d0 d85c 8a13 2737 3282 8efc f579 0000020 b83c 80f8 f659 0004 c654 e81b d7cf d43f 0000030 2145 39f7 6294 c78f 01c3 fa35 9a92 0fb0 0000040 # BASH SNIPPET ENDS ; ZONE FILE FRAGMENT STARTS ; The RDBDKEY RR for my.example is... my.example. 3600 IN RDBDKEY 0 3 15 ( NT/DHhFoyR8K9l1sJv1EH7fflnGiOnRrs+yGvo01tkg= ) ; The RDBD RR to be published by my-way.example is... my-way.example. 3600 IN RDBD 1 my.example 35988 15 ( ZLxETOdZ+5Q1/pwYdeskHE7G0Jlc2BOKNyeCMvyOefU8uPiA WfYEAFTGG+jP1z/URSH3OZRij8fDATX6kpqwDw== ) ; ZONE FILE FRAGMENT ENDS Brotman & Farrell Expires January 9, 2020 [Page 14] Internet-Draft RDBD July 2019 Appendix B. Ed25519 Signing Code Since OpenSSL does not yet support Ed25519 signing via its command line tool, we generate our example using the python script below, which is called as "ed25519-signer.py" above. This uses the python library from Appendix A of [RFC8032]. #!/usr/bin/env python3 # CODE_BEGINS import argparse, sys, binascii from eddsa2 import Ed25519 # from https://gist.github.com/wido/4c6288b2f5ba6d16fce37dca3fc2cb4a def calc_keyid(flags, protocol, algorithm, dnskey): st=struct.pack('!HBB', int(flags), int(protocol), int(algorithm)) st+=base64.b64decode(dnskey) cnt = 0 for idx in range(len(st)): s = struct.unpack('B', st[idx:idx+1])[0] if (idx % 2) == 0: cnt += s << 8 else: cnt += s return ((cnt & 0xFFFF) + (cnt >> 16)) & 0xFFFF def main(): parser=argparse.ArgumentParser(description='Ed25519 signing') parser.add_argument('-s','--secret', dest='secret', help='secret key') parser.add_argument('-r','--relating', dest='relating', help='relating domain') parser.add_argument('-d','--related', dest='related', help='related domain') parser.add_argument('-n','--negative', dest='negative', help='negative assertion') args=parser.parse_args() if args.secret is None: print("You do need a secret... - exiting") sys.exit(1) # secret has to be 32 octets funnily enuugh:-) # e.g. secret="rdbd-example0001rdbd-example0002".encode('utf-8') if len(args.secret)!=32: print("Secret has to be 32 octets... - exiting") sys.exit(1) if args.relating is None: print("You do need a relating domain... - exiting") Brotman & Farrell Expires January 9, 2020 [Page 15] Internet-Draft RDBD July 2019 sys.exit(1) if args.related is None: print("You do need a related domain... - exiting") sys.exit(1) secret=args.secret.encode('utf-8') privkey,pubkey = Ed25519.keygen(secret) print("private:"+ str(binascii.hexlify(privkey))) print("public:"+ str(binascii.hexlify(pubkey))) b64pubkey=binascii.b2a_base64(pubkey).rstrip().decode("utf-8") print("b64pubkey: " + b64pubkey) keyid=calc_keyid("0","3","15",b64pubkey) print("keyid: " + str(keyid)) rdbdtag="1" if args.negative: rdbdtag="0" tbs="relating="+args.relating+"\nrelated="+\ args.related+"\nrdbd-tag="+rdbdtag+\ "\nkey-tag="+str(keyid)+"\nsig-alg=15\n" print("to-be-signed:|" + str(tbs)+"|") with open("ed25519.priv", "wb") as privf: privf.write(privkey) with open("ed25519.pub","wb") as pubf: pubf.write(pubkey) with open("to-be-signed-15.txt","wb") as tbsf: tbsf.write(tbs.encode('utf-8')) msg=tbs.encode('utf-8') signature = Ed25519.sign(privkey, pubkey, msg) print("sig:"+ str(binascii.hexlify(signature))) with open("ed25519.sig", "wb") as sigf: sigf.write(signature) return if __name__ == "__main__": main() # CODE_ENDS Appendix C. Changes and Open Issues [[RFC editor: please delete this appendix ]] Brotman & Farrell Expires January 9, 2020 [Page 16] Internet-Draft RDBD July 2019 C.1. Changes from -01 to -02 o Added negative assertions based on IETF104 feedback o Added URL option based on IETF104 feedback o Made sample generation script o Typo fixes etc. C.2. Changes from -00 to -01 o Changed from primary/secondary to relating/related (better suggestions are still welcome) o Moved away from abuse of TXT RRs o We now specify optional DNSSEC-like signatures (we'd be fine with moving back to a more DKIM-like mechanism, but wanted to see how this looked) o Added Ed25519 option o Re-worked and extended examples C.3. Open Issues Current open github issues include: o #5: specify input for signing more precisely - e.g. is there a CR or NULL or not o #6: what, if anything, does rdbd for example.com mean for foo.example.com? These can be seen at: Authors' Addresses Alex Brotman Comcast, Inc Email: alex_brotman@comcast.com Brotman & Farrell Expires January 9, 2020 [Page 17] Internet-Draft RDBD July 2019 Stephen Farrell Trinity College Dublin Email: stephen.farrell@cs.tcd.ie Brotman & Farrell Expires January 9, 2020 [Page 18]