Decentralized Trust Chains (DTCs)
Learn about Decentralized Trust Chains (DTCs) on cheqd.
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Learn about Decentralized Trust Chains (DTCs) on cheqd.
Last updated
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Verifiable Credentials (VCs) are most commonly issued by legal entities to assert facts such as identity, qualifications, or authorisation. Their core purpose is to provide the Relying Party â the entity verifying the credential â with a Level of Assurance (LoA) that the claims within the credential are legitimate.
However, in practice, itâs often difficult for relying parties to determine whether a legal entity issuing a credential is authentic, or a fraudulent impersonation. There is no built-in mechanism in most credential ecosystems for verifying whether a DID-based issuer is recognised, authorised, or trustworthy.
To fully establish trust, relying parties must be able to:
Identify who issued a credential
Understand whether the issuer was authorised to issue it
Trace who accredited the issuer, and under what governance framework
To solve this challenge, cheqd introduces a verifiable trust infrastructure called Decentralized Trust Chains (DTCs) â a model that complements and extends approaches like the EBSI Trust Chain Framework.
DTCs allow participants to create hierarchical chains of trust, where:
A Root Trusted Accreditation Organisation (rTAO) defines the governance model
Verifiable Accreditations delegate authority to other legal entities (e.g., TAOs, Trusted Issuers)
Verifiable Credentials are issued by accredited issuers, with embedded metadata that references the trust chain
Together, these components form a decentralized trust registry for each ecosystem.
cheqdâs DTC model introduces both permissions and policies:
Permissions define what an entity is allowed to do (e.g. issue or accredit)
Policies define who granted that permission, under what framework, and with what legal or operational requirements.
This infrastructure is made publicly resolvable by publishing all authorisations and accreditations as DID-Linked Resources on the cheqd ledger. This means:
đ§Š Trust relationships are machine-verifiable
đ Verifiers do not need prior knowledge of each entity
đ ī¸ Resolution follows W3C standards like DID-Core, DID Resolution and DID-Linked Resources.
The result: A scalable, cryptographically verifiable way to determine whether an issuer â and the credential they issue â can be trusted.
There are many terms used within this guide, and as such, familiarise yourself or refer back to the concepts within the glossary below:
-
Accreditation Policy
A machine-readable policy embedded in a Verifiable Accreditation that defines the scope, conditions, and governance under which an entity is authorised to accredit others or issue Verifiable Credentials.
-
Attestation Policy
A machine-readable policy embedded in a Verifiable Credential that links the credential to the issuerâs accreditation and root authorisation, enabling verifiers to validate that the issuer was authorised to make the attestation.
DID
Decentralized Identifier
Legal entity identifier for Trust Registry, cannot be natural person in context of Trust Infrastructure
GA
Governance Authority
The legal entity or consortia responsible for writing the Governance Framework. In many instances the Governance Authority is also a Root TAO
GF
Governance Framework
A policy document outlining the purpose, roles, scopes and permissions for a given ecosystem using the Trust Infrastructure.
Root TAO (rTAO)
Root Trusted Accreditation Organization
A Root Trusted Accreditation Organisation (rTAO) is the top-level authority in a Decentralized Trust Chain responsible for defining the governance framework and issuing the Root Authorisation that anchors all downstream accreditations and attestations within the trust ecosystem.
TAO
Trusted Accreditation Organization
A Trusted Accreditation Organisation (TAO) is an entity accredited by a Root Trusted Accreditation Organisation (rTAO) or another TAO to govern a segment of the trust chain by issuing accreditations to other entities or authorising the issuance of Verifiable Credentials within a defined scope.
-
Trust Chain
Hierarchy of Verifiable Accreditations. Multiple Trust Chains may comprise a Trust Registry.
TI
Trusted Issuer
A Trusted Issuer is an entity accredited within a Decentralized Trust Chain to issue domain-specific Verifiable Credentials, operating under the scope and governance defined by an upstream accreditation and the overarching trust framework.
-
Trust Infrastructure
The overall set of technical and governance components to establish end-to-end trust.
-
Verifiable Accreditation
A Verifiable Accreditation is a Verifiable Credential that delegates authority from one entity to another, specifying the types of credentials they are permitted to issue or the roles they are authorised to perform within a defined trust framework.
-
Verifiable Trust Model
Permissions with policies to either accredit, or to attest
Decentralized Trust Chains are based on the concept of a hierarchical trust model, conceptually similar to traditional Public Key Infrastructure (PKI). At the top sits a Root of Trust, from which trust is delegated through a verifiable chain of credentials.
In this model, each participant is identified by a Decentralized Identifier (DID) and may be granted permission â via a Verifiable Accreditation â to accredit others or issue credentials themselves.
Trust is delegated top-down through Verifiable Accreditations:
Root TAO (rTAO)
Issues Root Authorisations and initial Accreditations to other TAOs. Sets the governance baseline.
Trusted Accreditation Organisation (TAO)
Can accredit other TAOs or Trusted Issuers. Acts as an intermediary layer in larger ecosystems.
Trusted Issuer (TI)
Issues Verifiable Credentials to users/entities, based on permissions received from an upstream TAO.
The following diagram show how a Root TAO accredits two TAOs lower in the hierarchy:
Each role is cryptographically linked through issued Verifiable Credentials, creating a machine-verifiable trust path.
Credentials are issued with a termsOfUse
section that references an Attestation Policy, linking them back to the issuerâs accreditation and the root of trust.
Digital Wallets or agents can present these credentials for verification.
Verifiers can then resolve and validate the entire trust chain â from the issuer to the rTAO â using DID resolution and optional DNS anchoring.
As shown in the diagram above, legal entities can play the following roles:
In a Decentralized Trust Chain, each legal entity assumes a defined role with clearly scoped permissions. While a single DID may represent multiple roles in simple ecosystems, every complete trust chain should include these three functional roles:
Root Trusted Accreditation Organisation (rTAO)
Trusted Accreditation Organisation (TAO)
Trusted Issuer (TI)
Only the Trusted Issuer (TI) is permitted to issue domain-specific Verifiable Credentials (VCs).
The rTAO is the root of governance in a trust chain. It establishes the ecosystemâs rules and authorises who can issue or accredit within it.
Capabilities:
Issue a Root Authorisation that defines the Trust Framework
Self-accredit for governance or issuance
Accredit TAOs and TIs to delegate responsibility
Revoke accreditations from any participant in the trust chain
Credential Type:
VerifiableAuthorisationForTrustChain
Policy Type:
TrustFrameworkPolicy
(included in termsOfUse
)
A TAO manages a delegated segment of the trust chain under the rTAO. It may further accredit entities or take on the role of issuer if permitted.
Capabilities:
Accredit itself to issue VCs
Accredit other TAOs or Trusted Issuers
Revoke accreditations issued within its scope
Credential Type:
VerifiableAccreditationToAccredit
Policy Type:
AccreditationPolicy
(included in termsOfUse
)
A Trusted Issuer is an entity that issues domain-specific Verifiable Credentials under the conditions granted by its accreditation.
Capabilities:
Issue Verifiable Credentials to users or organisations
Only within the types, schemas, and jurisdictions defined in their accreditation
Credential Type:
VerifiableAccreditationToAttest
Policy Type:
AccreditationPolicy
(accreditation) +
AttestationPolicy
(included in the issued credentialâs termsOfUse
)
Policies define the rules, permissions, and governance bindings for each layer of the trust chain. They are embedded into credentials via the termsOfUse
field and fall into three types:
TrustFrameworkPolicy
Root Authorisation
Defines the root governance model
AccreditationPolicy
Verifiable Accreditation
Constrains and describes the scope of authority
AttestationPolicy
Verifiable Credential
Links the credential back to the issuerâs accreditation and trust framework
Root Authorisation includes a TrustFrameworkPolicy
Each Accreditation must reference:
A parent AccreditationPolicy
, or
The original TrustFrameworkPolicy
Each Credential (Attestation) must reference:
The AttestationPolicy
pointing back to the issuerâs accreditation
This layered policy model enables verifiers to traverse and validate the entire trust chain â from a single credential back to a rTAO (optionally anchored in DNS) â while ensuring that all participants adhere to consistent governance and operational standards.
Trust Chains are constructed from three verifiable building blocks:
Define the rules of the ecosystem
Issued by the rTAO as a VerifiableAuthorisationForTrustChain
Reference the root governance framework
Grant permission to accredit or issue
Are always domain-specific and non-transferable
Must include an AccreditationPolicy
in termsOfUse
Allow entities to govern or issue only within the authorised scope
Assert facts (identity, qualifications, rights)
Must include an AttestationPolicy
that:
Links back to the issuer's accreditation
Establishes a trust path to the root authority
Issuable only by accredited Trusted Issuers
Element
Purpose
Authorisations
Define the governance and policy rules at the root of the trust chain
Accreditations
Delegate trust authority for accreditation or credential issuance
Credentials (Attestations)
Assert verifiable facts within the scope of a governed trust framework
Use cheqd Studio APIs to define, issue, and publish trust registry entries:
Create and manage Root Authorisations, Accreditations, and Attestations
Resolve trust chains in real time using standard DID resolution
Anchor trust registries on-chain while keeping business logic off-chain
For verification, use TRAIN to validate the trust registry to determine whether an issuer DID is accredited, and what they are accredited for â by traversing the full trust chain to its root.
Root Authorisations
Learn how Root TAOs can set the governance baseline, including the governance framework for the trust chain through Root Authorisations.
RTAO -> TAO
Learn about how Root TAOs can accredit other TAOs in the trust ecosystem with permissions and Trust Framework Policies.
TAO -> SubTAO
Learn about how TAOs can accredit other SubTAOs in the trust ecosystem with permissions and Accreditation Policies.
TAO - TI
Learn about how TAOs can accredit Trusted Issuers to issue credentials within the trust ecosystem, using permissions and Accreditation Policies.
Referencing Trust Registry within a Verifiable Credential
Learn how a Trusted Issuer can reference a Trust Registry in an issued credential, enabling a relying party to traverse the Trust Chain.