A Credential Registry is a verifiable data registry that acts as the authoritative source for the status and schema of digital credentials, ensuring issuers can publish credentials and verifiers can check their validity without relying on a direct connection to the issuer. It is a foundational component in architectures like W3C Verifiable Credentials, where it manages public keys, credential revocation lists (such as a Status List), and credential definitions to prevent fraud. By providing a decentralized point of trust, it solves the key problem of credential verification at scale, enabling ecosystems where credentials from one organization can be reliably checked by another.
LABS
Glossary
Credential Registry
A Credential Registry is a verifiable data registry, which may be decentralized, that stores public information necessary for credential verification, such as schemas, definitions, or revocation lists.
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definition
DECENTRALIZED IDENTITY
What is a Credential Registry?
A Credential Registry is a tamper-evident, trusted database that issues, stores, and verifies digital attestations, forming a core component of decentralized identity (DID) and verifiable credential (VC) ecosystems.
The registry itself does not typically store the private, user-held credential data but instead holds the metadata required to verify it. This includes the DID (Decentralized Identifier) of the issuer, the public key used for cryptographic signatures, the credential schema defining its data structure, and revocation information. When a verifier receives a credential, they query the registry—often referenced by a credentialStatus field—to confirm the issuer is authorized, the credential format is correct, and the credential has not been revoked. This separation of the credential from its proof of validity is essential for user privacy and data minimization.
Implementations vary, ranging from centralized databases operated by trusted institutions to fully decentralized networks using blockchain or other distributed ledger technology (DLT). Blockchain-based registries, such as those used by Indy, Veramo, or Ethereum-based systems, leverage the ledger's immutability to create a transparent and auditable record of which DIDs are authorized to issue specific credential types. This creates a system of trust over IP, where trust is managed through verifiable technical proofs rather than proprietary, siloed databases, enabling interoperable digital identity across organizational and national borders.
how-it-works
DECENTRALIZED IDENTITY
How a Credential Registry Works
A credential registry is a tamper-evident, decentralized database that anchors, manages, and verifies the status of digital attestations, such as academic degrees or professional licenses, without relying on a central issuing authority.
At its core, a credential registry functions as the authoritative source of truth for the issuance status and revocation state of verifiable credentials (VCs). When an issuer, like a university, creates a credential for a holder, it publishes a cryptographic commitment—often a digital fingerprint or hash—of that credential to the registry, typically anchored on a blockchain or other distributed ledger. This creates an immutable, timestamped record that the credential was validly issued at a specific point in time, establishing a foundational layer of trust.
The registry's primary technical mechanisms involve managing status lists and schema definitions. Status lists, such as revocation registries, allow issuers to signal if a credential has been revoked without revealing the credential's contents, preserving holder privacy. Schema definitions, published to the registry, provide the standardized data model that defines the structure and meaning of the credential's claims, ensuring interoperability between different systems and verifiers. This separation of the credential's portable data (held by the user) from its authoritative status (anchored on the registry) is a key innovation.
For verification, when a holder presents a credential, a verifier (like an employer) can query the credential registry using a unique identifier from the VC. The registry returns proof—cryptographically verifiable against the underlying blockchain—that the credential's schema is recognized, the issuer is authorized, and the credential is not revoked. This process enables cryptographic trust without the verifier needing to contact the issuer directly for every check, enabling scalable, privacy-preserving credential verification across organizational and national boundaries.
key-features
ARCHITECTURE
Key Features of a Credential Registry
A credential registry is a decentralized database for issuing, storing, and verifying attestations. Its core features ensure data integrity, user sovereignty, and interoperability across applications.
01
Decentralized Storage & Immutability
Credential data is anchored to a public blockchain (like Ethereum or Solana) or stored in decentralized networks (like IPFS or Ceramic). This creates an immutable audit trail, ensuring credentials cannot be altered or deleted after issuance, which is critical for establishing trust and provenance.
02
User-Centric Data Control
The registry employs a holder-centric model, where the credential subject (holder) controls their attestations. Credentials are stored in a user-owned wallet (e.g., a crypto wallet). The holder can selectively disclose proofs without revealing the underlying data, enabling privacy-preserving verification.
03
Standardized Schemas & Interoperability
Registries use open standards like W3C Verifiable Credentials (VCs) and Decentralized Identifiers (DIDs). This ensures credentials issued by one entity (an issuer) can be understood and trusted by any verifier in the ecosystem, breaking down data silos and enabling portable digital identity.
04
Cryptographic Proof & Verification
Every credential is cryptographically signed by the issuer's private key, creating a verifiable proof. A verifier can check this signature against the issuer's public DID on the registry to instantly confirm authenticity and that the credential has not been tampered with, without contacting the issuer.
05
Revocation & Status Management
Registries provide mechanisms to manage credential lifecycle. Common methods include:
- Revocation Registries: A list of revoked credential IDs.
- Status Lists: Bitstrings indicating active/revoked status.
- Smart Contract Functions: On-chain logic to invalidate credentials. This allows issuers to revoke credentials (e.g., for a expired license) while preserving holder privacy.
06
Composability & Programmable Logic
Credentials can be combined and evaluated using zero-knowledge proofs (ZKPs) or smart contracts to create complex attestations. For example, proving you are over 21 without revealing your birthdate, or meeting a multi-signature requirement for a DAO proposal. This enables trustless, automated decision-making.
core-functions
ARCHITECTURE
Core Functions of a Credential Registry
A credential registry is a decentralized database that anchors, manages, and verifies digital attestations. Its core functions ensure the integrity, availability, and utility of verifiable credentials.
01
Anchoring & Immutable Storage
The registry provides a cryptographic anchor for credential metadata, such as issuer public keys and revocation lists, onto a blockchain. This creates an immutable audit trail and a single source of truth. The credential data itself is typically stored off-chain (e.g., in a decentralized storage network) for efficiency, with its hash anchored on-chain to guarantee its integrity.
02
Issuer Registration & Key Management
It maintains a public directory of authorized issuers. This involves registering the issuer's Decentralized Identifier (DID) and their public keys used for signing credentials. The registry allows for key rotation and updates, enabling issuers to revoke old keys and publish new ones without breaking the trust chain for previously issued credentials.
03
Credential Status & Revocation
The registry manages the revocation status of credentials. Instead of storing the credential itself, it maintains a revocation list (e.g., a bitmap or a Merkle tree) that issuers can update. Verifiers query the registry to check if a credential's unique identifier is on the list, providing a scalable and privacy-preserving way to invalidate credentials.
04
Schema Definition & Resolution
It stores and resolves credential schemas—the standardized templates that define the structure and data fields of a credential type (e.g., a university degree). This ensures all parties (issuer, holder, verifier) share a common understanding of the credential's data model, enabling interoperable verification across different systems and registries.
05
Verification & Proof Resolution
The registry acts as a trusted resolution service for verifiers. To verify a credential, a verifier queries the registry to:
- Resolve the issuer's current public key.
- Fetch the credential's schema.
- Check the credential's revocation status. This process allows the verifier to cryptographically validate the credential's signature and authenticity without relying on a central authority.
06
Interoperability & Discovery
By adhering to open standards like W3C Verifiable Credentials and DID, the registry enables credentials to be understood and trusted across different ecosystems. It provides discoverable endpoints and metadata that allow wallets, verifiers, and other registries to interact with it seamlessly, forming the backbone of a decentralized identity network.
ARCHITECTURE COMPARISON
Types of Credential Registries
A comparison of the core architectural models for managing and verifying decentralized credentials, focusing on data location, trust, and revocation.
| Architectural Feature | On-Chain Registry | Off-Chain Registry (Indexed) | Hybrid Registry |
|---|---|---|---|
Data Storage Location | Public blockchain (e.g., Ethereum, Solana) | Decentralized storage (e.g., IPFS, Arweave) | Status/pointer on-chain, credential data off-chain |
Verification Trust Anchor | Smart contract state | Digital signature on the credential itself | Smart contract status + credential signature |
Revocation Mechanism | Direct state update on-chain | Revocation list published to storage | Status bit flipped on-chain |
Typical Gas/Cost for Issuance | $10-50+ | < $0.01 | $2-10 |
Credential Privacy | Low (status/ID is public) | High (data encrypted or selectively disclosed) | Medium (status public, data private) |
Query Performance | ~3-30 seconds (block time) | < 1 second | ~3-30 seconds for status, <1s for data |
Example Protocols/Frameworks | Ethereum Attestation Service (EAS) | W3C Verifiable Credentials (JSON-LD) | Veramo, Dock Network |
examples
CREDENTIAL REGISTRY
Examples & Implementations
A Credential Registry is a verifiable data registry that anchors and manages decentralized identifiers (DIDs) and their associated verifiable credentials. It provides a tamper-evident system for issuing, discovering, and resolving credentials without a central authority.
01
Verifiable Data Registry (VDR)
The foundational component of a credential registry, a Verifiable Data Registry is a system that enables the creation and verification of decentralized identifiers (DIDs) and their associated public keys. It provides the necessary infrastructure for DID resolution, allowing any party to look up the cryptographic material needed to verify a credential's signature. Common implementations include:
- Blockchains (e.g., Ethereum, Sovrin, Cardano)
- Distributed Ledgers
- Decentralized File Systems (e.g., IPFS for storing schemas)
- Purpose-Built Networks (e.g., ION on Bitcoin)
03
Ethereum as a Registry (ERC-1056/ERC-780)
Ethereum functions as a credential registry through smart contract standards that map DIDs to Ethereum addresses and manage verifiable claims.
- ERC-1056 (Ethr-DID): A method where an Ethereum address controls a DID. The registry is the Ethereum blockchain itself, with public keys resolvable via smart contracts.
- ERC-780: A standard for a claims registry, a smart contract that holds signed claims (attestations) about any identity (Ethereum address or DID). Anyone can query the contract to verify if a specific claim exists and is valid.
05
Schema & Definition Registries
A critical sub-component of a credential registry that stores the machine-readable schemas and credential definitions required for issuance and verification.
- Schema Registry: Publishes the structure (data fields) of a verifiable credential (e.g., "Driver's License Schema").
- Credential Definition (Indy/AnonCreds): Contains the public key used by an issuer to sign credentials of a specific schema, enabling zero-knowledge proofs.
- Status Registry: Manages revocation registries (e.g., accumulators, bitmaps) to check if a credential has been revoked, often implemented as a smart contract or a verifiable data structure.
security-considerations
CREDENTIAL REGISTRY
Security & Trust Considerations
A credential registry is a tamper-evident, decentralized database that anchors and verifies the issuance and status of digital credentials, forming a critical trust layer for decentralized identity (DID) and verifiable credentials (VCs).
01
Decentralized Identifier (DID) Anchoring
A credential registry anchors Decentralized Identifiers (DIDs) to a blockchain, providing a globally resolvable endpoint for a subject's public keys and service endpoints. This creates a cryptographic root of trust independent of any central authority. The registry does not store personal data but publishes the DID Document (DIDDoc), enabling verifiers to authenticate credential signatures.
- Key Function: Publishes and updates the DID Document.
- Trust Model: Shifts from centralized certificate authorities to verifiable on-chain proofs.
02
Credential Status & Revocation
The registry manages the status of issued verifiable credentials, a critical function for security. Instead of contacting the issuer directly, a verifier checks the registry for a revocation list (e.g., a Status List 2021 bitstring) or a credential status index. This provides a real-time, tamper-proof mechanism to invalidate credentials if a private key is compromised or attributes change.
- Status List: A compressed bitstring where each bit represents a credential's revoked/active state.
- Privacy: Bitstring approaches allow status checks without revealing which specific credential is being verified.
03
Immutable Audit Trail
Every credential issuance, update, and revocation event is recorded as an immutable transaction on the underlying ledger (blockchain, DAG, etc.). This creates a permanent, publicly auditable history of all registry operations. Auditors can cryptographically verify the entire lifecycle of a credential, ensuring non-repudiation and detecting any unauthorized alterations.
- Transparency: Anyone can verify the provenance and history of a credential's status.
- Evidence: Provides cryptographic proof of the issuer's actions for compliance and dispute resolution.
04
Key Rotation & Compromise Recovery
A core security feature is enabling secure key rotation for DIDs. If an issuer's or holder's private key is suspected to be compromised, the registry allows the publication of a new DID Document with updated public keys. This process, governed by the DID's verification method and authentication suites, prevents an attacker from issuing fraudulent credentials while preserving the identity's continuity and all previously issued valid credentials.
- Recovery: Uses pre-defined verification relationships or delegated authorities to authorize key updates.
- Continuity: The DID itself remains constant, only the cryptographic keys change.
06
Privacy-Preserving Verification (ZKPs)
Advanced registries support privacy-enhancing technologies like Zero-Knowledge Proofs (ZKPs). A verifier can confirm a credential is valid and unrevoked by checking a proof against the registry's state, without learning the credential's contents or the holder's identity. This enables selective disclosure (e.g., proving you are over 21 without revealing your birthdate) and minimizes correlation risks, aligning with data minimization principles of GDPR and similar regulations.
CREDENTIAL REGISTRY
Common Misconceptions
Clarifying widespread misunderstandings about the role, security, and technical implementation of credential registries in decentralized identity systems.
No, a credential registry is not a database of personal data; it is a tamper-evident ledger of credential metadata and public keys. The registry stores status information (like revocation lists), DID Document locations, and schema definitions, but never the actual personal claims or attributes contained within a Verifiable Credential. The personal data remains with the credential holder, typically in a wallet, and is only shared directly with verifiers. This architecture is fundamental to the principle of data minimization and user sovereignty in decentralized identity.
CREDENTIAL REGISTRY
Frequently Asked Questions (FAQ)
Essential questions and answers about decentralized credential registries, their technical architecture, and their role in verifiable data ecosystems.
A credential registry is a decentralized, tamper-evident system for issuing, storing, and verifying the status of digital credentials, such as Verifiable Credentials (VCs). It operates as a public, permissioned ledger where Issuers publish cryptographic proofs (like DID identifiers and schema definitions) and status lists (e.g., for revocation), allowing Verifiers to independently check a credential's validity without contacting the issuer directly. This is achieved through on-chain smart contracts or decentralized identifiers (DIDs) anchored to a blockchain, creating a trust layer for digital identity and attestations.
Key components include:
- Registry Smart Contract: The on-chain logic managing credential schemas and issuer permissions.
- Status List: A mechanism (like a revocation registry) to check if a credential is still valid.
- Decentralized Identifier (DID): A cryptographically verifiable identifier for the issuer, subject, or registry itself.
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