How to Architect a Self-Sovereign Identity (SSI) Provider for Your Users

A Self-Sovereign Identity (SSI) provider is a software system that enables users to create, control, and use verifiable credentials (VCs) and decentralized identifiers (DIDs) without relying on a central authority. Architecting this system requires a clear separation between the user's identity wallet (the client) and the backend services that facilitate credential issuance, verification, and DID resolution. The provider's architecture must prioritize user sovereignty, meaning private keys and sensitive data should never leave the user's device unless explicitly encrypted for a specific purpose.

The core architectural components include a DID resolver to interact with various DID methods (e.g., did:ethr, did:key, did:web), a verifiable data registry interface (often a blockchain), and secure protocols for credential exchange. The W3C Verifiable Credentials Data Model and DID Core specifications provide the foundational data structures. For interactions, the DIDComm v2 protocol or SIOPv2 (Self-Issued OpenID Connect Provider) are commonly used to establish secure, peer-to-peer communication channels between holders, issuers, and verifiers.

A critical design decision is choosing where to anchor DIDs. You can use a public permissionless blockchain like Ethereum for maximum decentralization, a permissioned ledger like Hyperledger Indy for enterprise control, or even a cloud-based method like did:web for simpler use cases. Each choice involves trade-offs in cost, throughput, and trust assumptions. The provider must also implement robust key management, supporting secure storage, rotation, and recovery of cryptographic keys, which is often handled by the user's wallet using hardware security modules or secure enclaves.

For developers, building an SSI provider backend typically involves exposing a set of RESTful APIs or GraphQL endpoints. Key endpoints include /did/create, /credential/issue, and /presentation/verify. Here's a simplified Node.js example for a DID creation endpoint using the did:key method:

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app.post('/did/create', async (req, res) => {
  const keyPair = await generateKeyPair('Ed25519');
  const did = `did:key:${keyPair.publicKeyMultibase}`;
  // Store public key mapping in your registry
  await storeDIDDocument(did, keyPair.publicKeyJwk);
  res.json({ did, publicKey: keyPair.publicKeyJwk });
});

The architecture must also plan for credential status (e.g., revocation registries), selective disclosure using zero-knowledge proofs (like BBS+ signatures), and interoperability with other SSI ecosystems. Testing should involve suites like the W3C VC Test Suite and Interoperability profiles from the Decentralized Identity Foundation. Successful deployment requires careful consideration of scalability, as DID resolution and proof verification can be computationally intensive during high-volume verification events.

Ultimately, a well-architected SSI provider acts as invisible infrastructure. It empowers applications to request credentials seamlessly (e.g., "Sign in with your verifiable credential") and allows users to manage their digital identity across platforms. The end goal is to replace centralized login databases with user-held, cryptographically verifiable assertions, reducing data breaches and giving individuals true control over their personal data.

Self-Sovereign Identity (SSI) is a model where individuals or entities have sole ownership and control over their digital identities without relying on centralized authorities. The core architectural components are defined by the W3C standards: Decentralized Identifiers (DIDs) and Verifiable Credentials (VCs). A DID is a globally unique identifier, like did:ethr:0xabc123..., that is anchored to a decentralized ledger (e.g., Ethereum, Sovrin) and controlled via cryptographic keys. VCs are tamper-evident digital claims, such as a university degree or KYC attestation, issued by trusted entities and cryptographically signed.

To architect a provider, you must first select a DID method that defines how a DID is created, resolved, updated, and deactivated on a specific blockchain or network. Popular methods include did:ethr for Ethereum-compatible chains, did:key for simple key pairs, and did:web for domains. Your architecture needs a DID resolver to fetch the DID Document—a JSON-LD file containing public keys and service endpoints—from the chosen network. For development, libraries like did-resolver and universal resolvers from the Decentralized Identity Foundation are essential starting points.

The credential lifecycle—issuance, holding, and verification—is managed through Verifiable Credentials Data Model implementations. You'll need to handle JSON-LD proofs or JWT-based proofs for cryptographic signatures. For Ethereum-based systems, consider using EIP-712 structured signing for user-friendly credential presentations. Your provider's backend must securely manage key storage for users (e.g., using secure enclaves or HSM for issuers) and expose standard APIs for credential exchange, typically following protocols like OpenID for Verifiable Credentials (OIDC4VC) or W3C Credential Handler API for browser integration.

A critical decision is choosing the trust model and governance for your ecosystem. Will you use permissioned ledgers like Hyperledger Indy for high-trust enterprise scenarios, or public permissionless blockchains like Ethereum for open participation? Each has trade-offs in cost, throughput, and decentralization. Your architecture must also include a revocation mechanism, such as status lists or smart contract-based registries, to invalidate credentials without compromising user privacy through zero-knowledge proofs.

For practical implementation, start with a stack like Node.js with the did-jwt-vc library for JWT-signed VCs, or Veramo—a modular TypeScript framework for SSI agents. Your minimal provider must offer: a DID creation service, a secure wallet (custodial or non-custodial) for key management, endpoints for issuing and verifying credentials, and a user-facing app to present credentials via QR codes. Always prioritize privacy-by-design using techniques like selective disclosure and derived predicates to minimize data exposure during verification.

The Issuer is the entity that creates and digitally signs verifiable credentials (VCs). This could be a university issuing a diploma, a government issuing a passport, or a DAO issuing a membership attestation. The issuer's core technical responsibilities include defining the credential schema (e.g., AlumniCredential), populating it with claims (name, degree, date), and signing it with their cryptographic private key. This signature, often using Decentralized Identifiers (DIDs) and Verifiable Data Registries like Ethereum or Sovrin, provides cryptographic proof of the credential's origin and integrity. Issuers must maintain the security of their signing keys and publish their public DID to a ledger so verifiers can resolve and trust it.

The Holder is the individual or entity, often an end-user, that receives, stores, and controls the credentials issued to them. The holder uses a digital wallet—a secure application that manages their DIDs, private keys, and VCs. When a user wants to prove something about themselves, they do not send the raw credential. Instead, they create a verifiable presentation. This is a cryptographically verifiable package that can contain selective disclosures from one or more VCs, proving specific claims (like being over 18) without revealing the entire credential. The holder's wallet is the core of user sovereignty, enabling portability and consent-driven data sharing.

The Verifier is the party that needs to verify a claim about the holder. This could be a website requiring age verification, a DeFi protocol checking for accredited investor status, or an employer confirming a degree. The verifier's job is to request specific credentials or claims, receive a verifiable presentation from the holder, and cryptographically verify it. This process involves: checking the issuer's signature on the original credential, ensuring the credential has not been revoked (often by checking a revocation registry), and validating that the presentation is fresh and intended for them. The verifier trusts the issuer, not the holder, which is the foundational shift from centralized authentication.

These three roles interact through standardized protocols. The most common is the W3C Verifiable Credentials Data Model, which defines the JSON-LD structure for credentials and presentations. For secure, interoperable communication between wallets (holders) and websites/apps (verifiers/issuers), the W3C Decentralized Identifiers (DID) specification and protocols like OpenID for Verifiable Credentials (OIDC4VC) or DIDComm are used. These protocols ensure that credential issuance and presentation flows are secure, privacy-preserving, and work across different wallet implementations and trust frameworks.

Architecting your application within this model requires deciding which roles you will fulfill. Are you building a credential issuer service? You'll need a secure key management system and integration with a DID method. Building a user wallet? Focus on UX for credential storage and presentation, and SDKs like Veramo or Trinsic. Building a verifying service? You'll implement presentation request logic and verification libraries. The architecture is decentralized; there is no central database of identities. Trust is established through publicly verifiable cryptography and the reputations of issuers, creating a scalable and user-centric identity layer for the web.

A Self-Sovereign Identity (SSI) provider is a system that empowers users to own and control their digital credentials without relying on a central authority. At its core, an SSI architecture is built on three pillars: Decentralized Identifiers (DIDs) for user-controlled addresses, Verifiable Credentials (VCs) as digital attestations, and Verifiable Presentations (VPs) for sharing proofs. Your provider acts as the issuer, creating VCs that are cryptographically signed and anchored to a verifiable data registry, often a public blockchain like Ethereum or a dedicated ledger such as ION for Bitcoin.

The technical foundation begins with DID Method selection. You must implement or integrate a DID method like did:ethr, did:key, or did:web. This defines how DIDs are created, resolved, and updated. For issuance, you'll need a secure key management system to hold your issuer's private keys. A common pattern is to use a DID Document containing public keys and service endpoints, published to a chosen registry. The issuer's DID becomes the immutable issuer property in every VC, establishing cryptographic provenance.

To issue a credential, you construct a JSON object conforming to the W3C Verifiable Credentials Data Model. A minimal VC includes an id, issuer, issuanceDate, credentialSubject (the holder's DID and claim data), and a proof section. For example, a credential for a KYC check would include claims like "name" and "birthDate" within the credentialSubject. You then sign this payload using the cryptographic suite specified in your DID Document, such as Ed25519Signature2020 or JsonWebSignature2020, generating the linked data proof.

For production systems, you must decide on credential status and revocation. The VC standard supports status methods like Status List 2021, where a bitstring on a public HTTP endpoint or blockchain indicates revocation. Your issuer service must maintain this list and update it when credentials are revoked. Furthermore, consider selective disclosure using zero-knowledge proofs (e.g., BBS+ signatures) to allow users to prove specific claims without revealing the entire credential, enhancing privacy.

Finally, expose a well-defined API for your users (holders). This typically includes endpoints to request a credential, a secure delivery mechanism (often via a DIDComm encrypted message or a QR code), and a public endpoint for verifiers to resolve your issuer DID and verify credential proofs. By implementing these components—DID management, VC construction/signing, status tracking, and holder APIs—you architect a functional SSI provider that puts users in control of their verifiable digital identity.

A holder wallet is more than a key manager; it's a user's agent for interacting with the SSI ecosystem. Its primary functions are to securely store Verifiable Credentials (VCs) and generate Verifiable Presentations (VPs) for proving claims to verifiers. Architecting this system requires a clear separation between the storage layer (where credentials are kept) and the presentation layer (the logic for constructing proofs). This separation is critical for security, portability, and user experience, ensuring private keys and raw credential data are never exposed unnecessarily.

The storage layer must prioritize security and user sovereignty. For web and mobile applications, the W3C DIDComm v2 protocol is emerging as a standard for secure, encrypted messaging between wallets. Credentials are typically stored locally in an encrypted database (e.g., SQLCipher, Realm) or within a secure hardware enclave. A robust architecture implements key derivation from a user's master seed to create distinct keys for signing, encryption, and authentication, following standards like BIP-32 and BIP-44. Never store plaintext private keys or credentials on a centralized server.

The presentation layer handles the logic of proving claims. When a verifier (like a dApp) requests specific attributes (e.g., "prove you are over 18"), the wallet's presentation engine must: 1) Query its storage for relevant credentials, 2) Apply selective disclosure techniques—such as generating BBS+ signatures for predicate proofs ("age > 18") without revealing the exact birth date, and 3) Construct a Verifiable Presentation object as defined by the W3C. This VP bundles the proof and is signed by the holder's DID.

For developers, libraries like Veramo (TypeScript) and Aries Framework JavaScript (AFJ) provide essential building blocks. Below is a simplified example using Veramo to create a selective disclosure presentation from a stored credential.

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import { createAgent } from '@veramo/core';
import { CredentialPlugin } from '@veramo/credential-w3c';
// ... agent setup with DID resolver and key manager

// Create a Verifiable Presentation
const presentation = await agent.createVerifiablePresentation({
  presentation: {
    holder: 'did:ethr:0x123...', // Holder's DID
    verifiableCredential: [storedCredential], // The stored VC
  },
  proofFormat: 'jwt', // Or 'lds' for Linked Data Proofs
  challenge: 'verifier-supplied-nonce-123', // Prevent replay attacks
});
// Send `presentation` to the verifier

Key architectural decisions include choosing proof formats (JWT vs. JSON-LD with Data Integrity Proofs), managing DID methods (did:key, did:ethr, did:web), and ensuring interoperability via the W3C VC Data Model. The wallet should also support credential revocation status checks, often by querying a revocation list or a status registry on-chain. User experience is paramount; the UI must clearly explain what data is being shared and with whom during every presentation flow.

Ultimately, a well-architected holder wallet empowers users with true data ownership. By implementing secure, standards-based storage and a flexible presentation engine, you provide the foundation for privacy-preserving interactions across Web3, from DeFi KYC and DAO voting to professional credential verification. The code and design patterns you establish will determine the security and usability of your users' digital identities.

A Self-Sovereign Identity (SSI) provider is a system that enables users to create, manage, and present their own digital credentials without relying on a central authority. The core architectural shift is moving from centralized user databases to a holder-centric model, where the user's wallet or agent acts as the primary data custodian. This requires implementing three key W3C standards: Decentralized Identifiers (DIDs) for globally unique, user-owned identifiers, Verifiable Credentials (VCs) for cryptographically signed attestations, and Verifiable Presentations (VPs) for sharing selective proofs. Your provider's role is to issue VCs and verify VPs, not to store user data.

The user experience must be built around explicit, informed consent. Every data request must be clear, scoped, and revocable. Architecturally, this means your backend exposes a Verifier API that generates presentation requests. These requests, often formatted as Presentation Definitions (e.g., using DIF's Presentation Exchange specification), specify exactly which credentials are needed (e.g., "a verifiable credential proving the holder is over 18"). The user's wallet interprets this request and prompts them to approve or deny the sharing of the specific data points, with no option for the provider to request "everything."

For developers, implementing the issuance flow involves creating a secure endpoint that signs credentials. A minimal Node.js example using the did-jwt-vc library might look like:

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const { createVerifiableCredentialJwt } = require('did-jwt-vc');
const issuerKey = //... load your DID's private key
const vcPayload = {
  sub: 'did:ethr:0x123...', // Holder's DID
  vc: {
    '@context': ['https://www.w3.org/2018/credentials/v1'],
    type: ['VerifiableCredential', 'AgeVerificationCredential'],
    credentialSubject: { isOver18: true }
  }
};
const vcJwt = await createVerifiableCredentialJwt(vcPayload, issuerKey);
// Return vcJwt to the user's wallet

The signed JWT is the Verifiable Credential, which the user stores.

The verification flow is separate. When a user wants to access a service, your Verifier API sends a challenge (a presentation request). The user's wallet constructs a Verifiable Presentation, which is a wrapper around the relevant VCs, often signed as a JWT to prove control of the holder's DID. Your backend verifies this presentation by: 1) checking the JWT signature against the holder's DID Document, 2) validating the embedded VC signatures against the issuer's DID, and 3) confirming the credential claims satisfy the request. Libraries like did-jwt-vc or veramo handle this complex cryptography.

Key architectural decisions include choosing DID methods (e.g., did:ethr for Ethereum, did:key for simplicity), credential formats (JWT vs. JSON-LD with BBS+ signatures for selective disclosure), and communication protocols (OpenID Connect for SIOPv2, CHAPI, or direct QR code scanning). You must also design for key recovery and credential revocation. A common pattern is using revocation registries (like in AnonCreds) or status lists to check if an issued credential is still valid without tracking individual users.

Ultimately, a successful SSI provider architecture decouples identity from your application. Your systems become issuers and verifiers of trust, not repositories of personal data. This reduces liability, enhances user privacy, and creates interoperable digital identities. Focus on clean APIs for credential issuance and presentation verification, and ensure every user interaction clearly answers the question: "What am I sharing, with whom, and why?"

Building an SSI provider is an exercise in decentralized trust engineering. You have learned the foundational elements: the Decentralized Identifier (DID) as the user's anchor, the Verifiable Credential (VC) as the portable claim, and the Verifiable Presentation (VP) as the context-specific proof. The provider's role is to facilitate the secure issuance, storage, and presentation of these components while never acting as a central data custodian. Your architecture must prioritize user agency and cryptographic verifiability above all else.

For implementation, start by selecting a DID method and VC data model. For enterprise applications, the did:web or did:ion methods offer a practical starting point, while did:key is useful for testing. Adhere to the W3C Verifiable Credentials Data Model v2.0 for interoperability. Your code must handle JSON-LD contexts and cryptographic proof suites like Ed25519Signature2020 or BbsBlsSignature2020 for selective disclosure. Libraries like did-jwt-vc (JavaScript/TypeScript) or aries-cloudagent-python provide essential building blocks.

Next, integrate with trust frameworks and governance registries. Real-world utility depends on your provider's ability to resolve trusted issuers' DIDs and their public keys. This often involves querying a Verifiable Data Registry (VDR) like a blockchain (e.g., Ethereum for did:ethr) or a dedicated ledger (Indy Node). For testing, you can use the Trinsic Playground or the MATTR VII platform. Your architecture should abstract this layer to easily switch between networks.

The final step is designing the user experience. This includes secure key management (via hardware security modules or mobile secure enclaves), intuitive consent flows for credential sharing, and clear interfaces for users to audit their data exchanges. Remember, the holder's wallet—whether embedded in your app or a separate agent—is the critical user-facing component. It must balance security with usability to drive adoption.

To continue, explore these resources: the Decentralized Identity Foundation (DIF) specifications, the W3C VC Implementation Guidelines, and the OpenID Connect for Verifiable Credentials (OID4VC) standard. Building a compliant SSI provider is a commitment to an open ecosystem. Start with a narrow use case, ensure your implementation is auditable and open-source, and contribute back to the community shaping the future of digital identity.