Leveraging DNS in Digital Trust: Credential Exchanges and Trust Registries
draft-latour-dns-and-digital-trust-02
| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Jesse Carter , Jacques Latour , Mathieu Glaude | ||
| Last updated | 2024-04-11 | ||
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| Intended RFC status | (None) | ||
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draft-latour-dns-and-digital-trust-02
Network Working Group J. Carter
Internet-Draft J. Latour
Intended status: Informational CIRA
Expires: 13 October 2024 M. Glaude
NorthernBlock
11 April 2024
Leveraging DNS in Digital Trust: Credential Exchanges and Trust
Registries
draft-latour-dns-and-digital-trust-02
Abstract
This memo describes an architecture for trust registry membership
association and verification using Decentralized Identifiers (DIDs),
trust registries, and the DNS. This architecture provides a verifier
with a simple process by which to determine and verify an issuer's
membership in a trust registry.
About This Document
This note is to be removed before publishing as an RFC.
The latest revision of this draft can be found at
https://CIRALabs.github.io/DNS-Based-VCs-and-Trust-Registries-ID/
draft-DNS-Based-Digital-Verifiable-Credential-Verification-and-Trust-
Registry-Architecture.html. Status information for this document may
be found at https://datatracker.ietf.org/doc/draft-latour-dns-and-
digital-trust/.
Source for this draft and an issue tracker can be found at
https://github.com/CIRALabs/DNS-Based-VCs-and-Trust-Registries-ID.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 13 October 2024.
Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Note . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. The Role of Trust Registries in Bidirectional Credential
Verification . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Issuer's Membership Claim in a Trust Registry . . . . . . 6
4.1.1. URI Record Name Scoping . . . . . . . . . . . . . . . 6
4.2. Trust Registry Membership Proof . . . . . . . . . . . . . 6
5. Role of DNSSEC for Assurance and Revocation . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 8
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
This memo aims to demonstrate how trust registries can enable global
interoperability by providing a layer of digital trust in the use of
digital credentials, demonstrating that trust registries can
facilitate a more efficient and trustworthy credential verification
process. By leveraging the publicly resolvable and widely supported
DNS/DNSSEC infrastructure, entities looking to make a trust decision
can easily validate not only the integrity of the credential they are
presented with, but also quickly associate the entity in question
with a domain name and organization, as well as their authority and
trustworthiness by confirming their membership in a trust registry.
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We will explore how this implementation can present a more
decentralized approach to making trust decisions, without having to
integrate directly to all trust registries, but instead letting
entities involved in private transactions leverage existing internet
infrastructure to facilitate their own trust decisions.
We will focus this memo around a use case involving an individual or
an organization receiving a verifiable credential [AnonCreds]
[W3C-VC-Data-Model] from an issuer and storing it in their digital
wallet. When the individual needs to provide proof of identity or
other claims, they present the verifiable credential to a verifier in
the form of a verifiable claim which normally includes a digital
signature. The verifier then performs several steps to verify the
authenticity of the credential, including extracting the issuer's DID
from the credential, resolving it according to the corresponding did
method to obtain the issuer's DID document, verifying the signature
of the credential using the public key in the issuer's DID document,
and finally verifying the issuer through a trust registry grounded in
the DNS using URI and TLSA records, while ensuring all these DNS
records are properly signed and validated with DNSSEC.
This process allows for the secure and decentralized verification of
digital credentials in a manner that is transparent and auditable,
while also existing alongside and independent of the many different
decentralized identity ecosystems and implementations by grounding
itself in the DNS.
1.1. Note
The standardization of the various implementations of DIDs,
Verifiable Credentials, and more specifically, Trust Registries, is
required to to ensure global interoperability of the diverse and
emerging digital identity ecosystem.
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.
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3. Terminology
* *Issuer*: The source of credentials—every verifiable credential
has an issuer. Issuers can include organizations such as
government agencies (passports, verified person), financial
institutions (credit cards), universities (degrees), corporations
(employment IDs), churches (awards), etc. Individuals can issue
themselves self-attested credentials - and depending on the
governance framework of a digital credentialing ecosystem,
individuals could issue credentials to others.
* *Holder*: The recipient of digital credentials. The Holder stores
their credentials inside a digital wallet and uses agent
technology to interact with other entities. A Holder can be a
person, an organization or a machine.
* *Verifier*: A verifier can be anyone seeking trust assurance of
some kind about the holder of a credential. Verifiers request the
credentials they need and then follow their own policy to verify
their authenticity and validity. For example, a TSA agent at an
airport will look for specific features of a passport or driver’s
license to see if it is valid, then check to ensure it is not
expired.
* *Digital Wallet/Agent*: A digital wallet, in the context of
digital identity, is a secure platform or application that stores
and manages an individual's personal identification and
authentication credentials, such as government-issued IDs,
passports, driver's licenses, and biometric data in the form of
verifiable credentials. The Agent allows the subject to establish
unique, confidential, private and authentic channels with other
agents.
* *Verifiable Data Registry (VDR)*: A storage location where
information relating to Decentralized Identifiers (DIDs) and
credential metadata are stored. Permissionless blockchains or
permissioned distributed ledger networks can be used to facilitate
the discovery and resolution of DIDs and credential information.
* *Trust Registry*: Trust registries are services that help
determine the authenticity and authorization of entities in an
ecosystem governance framework. They allow governing authorities
to specify what actions are authorized for governed parties and
enable checking if an issuer is authorized to issue a particular
credential type. Essentially, trust registries serve as a trusted
source for verifying the legitimacy of credential issuers, wallet
apps, and verifiers.
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4. The Role of Trust Registries in Bidirectional Credential
Verification
A trust registry is a decentralized system that enables the
verification of the authenticity and trustworthiness of issuers of
digital credentials. Trust registries can be implemented using
distributed ledger technology and leverage the DNS to provide a
transparent and auditable record of issuer information.
When an entity is presented with a verifiable claim, there are three
things they will want to ensure:
1. That a claim hasn’t been altered/falsified at any point in time,
via cryptographic verifiability and Verifiable Data Registries
(VDRs).
2. That a claim has accurate representation via authentication, via
DID Discovery & mapping within DNS as described above.
3. That a claim has authority, or in other words, does the issuer
have authority in its issuance of credentials, via the use of
trust registries (or trust lists).
In this memo, trust registries enable the verification of the
authority of an issuer and by extent their credentials. The role of
a trust registry within the context of this document is to confirm
the authenticity and trustworthiness of the issuer to the verifier
after they have validated the digital credential using the mechanisms
described previously. This involves the trust registry taking on the
role of a trust anchor for a given ecosystem, providing input for the
verifier’s ultimate trust decision regarding the credential they are
being presented with. The assumption is made that the trust registry
would be operated under the authority of an institution or
organization such that their claims and input to the trust decision
would be considered significant or definitive. An example of such an
organization would be a government entity in relation to the issuance
of a driver’s licence.
It is important to note that the DNS based trust registry mechanism
described in this section is not meant to operate in place of an
alternative implementation but provide an easy to implement and use
mechanism to extend such a solution.
This section also does not describe the process of the trust
registry’s verification of an issuer, or the process of how an issuer
would become accredited by or join a trust registry.
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4.1. Issuer's Membership Claim in a Trust Registry
Once a verifier has successfully completed the credential
verification process, they have definitive proof that the credential
they are being presented with was issued by the claimed issuer.
However, this process does not provide definitive proof the issuer is
to be trusted or has the authority to issue such a credential. The
issuer, through use of URI records and the __trustregistry_ label,
can assert the claim that they are a member of a trust registry.
*_Ex: _trustregistry.example-issuer.ca IN URI 0 1 “example-
trustregistry.ca”_*
This record indicates the verifier can query the _example-
trustregistry.ca_ DNS based trust registry for TLSA records
containing _example-issuer.ca's_ public key/s, proving their
membership.
4.1.1. URI Record Name Scoping
When trust registry membership claims are published in the DNS
* The records MUST be scoped by setting the global (highest-level)
underscore name of the URI RRset to __trustregistry_ (0x5F 0x74
0x72 0x75 0x73 0x74 0x72 0x65 0x67 0x69 0x73 0x74 0x72 0x79)
4.2. Trust Registry Membership Proof
The trust registry can assert an issuer's membership using TLSA
records.
*_Ex: _example-issuer.ca._trustregistration.example-trustregistry.ca
in TLSA 3 1 0 “4e18ac22c00fb9...b96270a7b6”_*
Note that the first component of the URI is the issuer’s domain,
followed by the __trustregistration_ label. This combination
indicates that the domain expressed is registered by this trust
registry as per its governance model, and this is their public key.
This association created by the TLSA record effectively has created a
chain of trust, beginning at the Issuer's public key, continuing to
the issuer’s domain, and finally resolving at the Trust Registry.
5. Role of DNSSEC for Assurance and Revocation
It is a MUST that all the participants in this digital identity
ecosystem enable DNSSEC signing for all the DNS instances they
operate. See [RFC9364].
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DNSSEC provides cryptographic assurance that the DNS records returned
in response to a query are authentic and have not been tampered with.
This assurance within the context of the __did_ URI and __did_ TLSA
records provides another mechanism to ensure the integrity of the DID
and its public keys outside of the distributed ledger it resides on
directly from the domain of its owner.
Within this use-case, DNSSEC also provides revocation checks for both
DIDs and public keys. In particular, a DNS query for a specific
__did_ URI record or __did_ TLSA record can return an NXDOMAIN
[RFC8020] response if the DID or public key has been revoked. This
approach can simplify the process of verifying the validity of DIDs
and public keys by reducing the need for complex revocation
mechanisms or implementation specific technologies.
6. Security Considerations
TODO Security
7. IANA Considerations
This document has no IANA actions.
8. References
8.1. Normative References
[alsoKnownAs]
"Decentralized Identifiers (DIDs) v1.0", n.d.,
<https://www.w3.org/TR/did-core/#also-known-as>.
[AnonCreds]
"AnonCreds Specification", n.d.,
<https://hyperledger.github.io/anoncreds-spec/>.
[DID-in-the-DNS]
"The Decentralized Identifier (DID) in the DNS", n.d.,
<https://datatracker.ietf.org/doc/html/draft-mayrhofer-
did-dns-05#section-2>.
[DID-Specification-Registries]
"DID Specification Registries", n.d.,
<https://www.w3.org/TR/did-spec-registries/#did-methods>.
[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/rfc/rfc2119>.
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[RFC8020] Bortzmeyer, S. and S. Huque, "NXDOMAIN: There Really Is
Nothing Underneath", RFC 8020, DOI 10.17487/RFC8020,
November 2016, <https://www.rfc-editor.org/rfc/rfc8020>.
[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/rfc/rfc8174>.
[RFC9364] Hoffman, P., "DNS Security Extensions (DNSSEC)", BCP 237,
RFC 9364, DOI 10.17487/RFC9364, February 2023,
<https://www.rfc-editor.org/rfc/rfc9364>.
[services] "Decentralized Identifiers (DIDs) v1.0", n.d.,
<https://www.w3.org/TR/did-core/#services>.
[verificationMethod]
"Decentralized Identifiers (DIDs) v1.0", n.d.,
<https://www.w3.org/TR/did-core/#verification-methods>.
[W3C-VC-Data-Model]
"Verifiable Credentials Data Model v1.1", n.d.,
<https://www.w3.org/TR/vc-data-model/>.
8.2. Informative References
[Pan-Canadian_Trust_Framework]
DIACC, "PCTF Trust Registries Draft Recommendation V1.0
DIACC / PCTF13", n.d., <https://diacc.ca/wp-
content/uploads/2023/03/PCTF-Trust-Registries-Component-
Overview_Draft-Recomendation-V1.0.pdf>.
[Self-Sovereign_Identity]
Reed, D. and A. Preukschat, "Self-Sovereign Identity",
ISBN 9781617296598, 2021.
[ToIP_Trust_Registry_Specification]
Trust Over IP (ToIP) Working Group, "ToIP Trust Registry
Protocol V1 Specification", n.d.,
<https://github.com/trustoverip/tswg-trust-registry-
tf/blob/main/v1/docs/
ToIP%20Trust%20Registry%20V1%20Specification.md>.
Acknowledgments
TODO acknowledge.
Authors' Addresses
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Jesse Carter
CIRA
Email: jesse.carter@cira.ca
Jacques Latour
CIRA
Email: jacques.latour@cira.ca
Mathieu Glaude
NorthernBlock
Email: mathieu@northernblock.io
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