Self-Sovereign Identity (SSI)

SSI eliminates the need for a central identity provider by distributing trust across a network of peers. Instead of relying on a single authority like a government database or corporate login server, identity claims are anchored on verifiable data registries—typically distributed ledgers or blockchains.

• No single point of failure or compromise
• Resistant to mass data breaches
• Reduces vendor lock-in and platform dependency
• Enables peer-to-peer credential exchange without intermediaries

The identity holder—not an external administrator—determines exactly what information to share, with whom, and for how long. This is enforced through cryptographic consent mechanisms where the user explicitly signs each disclosure.

• Granular, per-attribute disclosure: share only your age, not your birthdate
• Revocable consent: permissions can be withdrawn at any time
• Selective disclosure using zero-knowledge proofs
• No silent background data sharing

Credentials in an SSI ecosystem are not locked inside a single platform. They reside in a digital wallet controlled by the user and can be presented across any service that accepts the underlying standard. This mirrors the physical world: you carry your driver's license and present it wherever needed.

• Built on open standards: W3C Verifiable Credentials and Decentralized Identifiers (DIDs)
• Interoperable across different vendors and jurisdictions
• No re-verification required when switching service providers
• Eliminates repetitive KYC onboarding processes

An SSI identifier is designed to be long-lived and durable. Unlike a corporate email address that vanishes when you leave a job, a Decentralized Identifier (DID) remains under the holder's control indefinitely. The identifier persists even if the underlying cryptographic keys are rotated.

• DID documents support key rotation without changing the identifier
• No dependency on a third party's continued operation
• Enables accumulation of a lifelong, portable reputation
• Survives organizational and jurisdictional changes

Every credential in an SSI system is cryptographically signed by its issuer. Relying parties can instantly verify the authenticity and integrity of a claim without contacting the original issuer. This is achieved through digital signatures anchored to a public DID on a verifiable data registry.

• Real-time cryptographic verification, not database lookups
• Credential revocation registries enable instant invalidation checks
• Tamper-evident: any alteration to a credential breaks the signature
• Supports holder binding to prevent credential replay attacks

SSI architectures enforce the principle of data minimization through advanced cryptographic techniques. A holder can prove a claim is true without revealing the underlying data. For example, proving you are over 21 without disclosing your exact birthdate, using zero-knowledge proofs (ZKPs) or BBS+ signatures.

• Predicate proofs: satisfy a condition without revealing the raw value
• Reduces liability for data processors who never see the raw data
• Aligns with GDPR Article 5(1)(c) data minimization requirements
• Prevents over-collection and function creep by relying parties

A globally unique, persistent identifier that does not require a centralized registration authority. DIDs are the foundational addressing layer of SSI, enabling entities to prove control via cryptographic keys.

• W3C Standard: Defined by the World Wide Web Consortium for interoperability
• Method Agnostic: Supports various ledgers (did:ethr, did:web, did:indy)
• Resolution: A DID resolves to a DID Document containing public keys and service endpoints
• Key Rotation: Supports cryptographic agility without changing the identifier itself

Tamper-evident digital credentials that can be cryptographically verified. VCs represent the claims an issuer makes about a subject—such as a university degree or a driver's license—that the holder can present to a verifier without contacting the issuer.

• Tripartite Model: Issuer, Holder, Verifier trust triangle
• Zero-Knowledge Proofs: Enable selective disclosure of specific claims
• Revocation: Supports credential status checks via registries or bitstring lists
• JSON-LD Format: Ensures semantic interoperability across domains

A cryptographic protocol where one party proves to another that a statement is true without revealing any information beyond the validity of the statement itself. In SSI, ZKPs enable selective disclosure—proving you are over 18 without revealing your exact birthdate.

• zk-SNARKs: Succinct, non-interactive proofs with minimal verification time
• BBS+ Signatures: Enables efficient multi-message selective disclosure
• Predicate Proofs: Prove relationships (greater than, less than) without revealing values
• Unlinkability: Prevents verifiers from correlating multiple presentations

A mathematical framework that injects calibrated statistical noise into query results to guarantee that the presence or absence of a single individual cannot be inferred. When combined with SSI, differential privacy protects aggregate analytics derived from verifiable credential data.

• Epsilon Parameter: Quantifies the privacy loss budget per query
• Global vs. Local: Centralized noise addition versus per-user perturbation
• Composition Theorems: Privacy loss accumulates predictably across multiple queries
• GDPR Alignment: Recognized by regulators as a robust anonymization technique

A centralized software solution that captures, stores, and manages user consent preferences for data collection and processing. SSI extends CMP functionality by enabling user-held consent receipts that travel with the identity rather than being siloed per service.

• IAB TCF Integration: Standardized consent signaling for ad tech ecosystems
• Granular Purposes: Per-purpose opt-in rather than bundled consent
• Consent Receipts: Verifiable proof of what was agreed to and when
• Cross-Domain Portability: Consent preferences that follow the user across services

A formal request by an individual to an organization to access, rectify, or delete their personal data, mandated by GDPR and CCPA. SSI architectures can automate DSAR fulfillment by giving users direct control over their data stores rather than requiring manual organizational retrieval.

• Article 15 GDPR: Right of access to personal data and processing information
• 30-Day Deadline: Organizations must respond within one calendar month
• Identity Verification: Critical step to prevent unauthorized data disclosure
• Automated Portability: SSI enables machine-readable data export by default