Self-Sovereign Identity

Self-sovereign identity (SSI) is a model of digital identity where individuals own and control their identity data—without depending on centralized authorities like governments, corporations, or platform providers to issue, verify, or revoke their credentials.

SSI is built on three technical pillars: decentralized identifiers (DIDs), verifiable credentials (VCs), and blockchain-based registries. A DID is a unique identifier that the holder creates and controls, not issued by any authority. Verifiable credentials are cryptographically signed attestations (a university degree, a driver's license, an age verification) that can be presented and verified without contacting the issuer. The W3C has standardized both DIDs and VCs, providing the interoperability layer for SSI implementations.

Government adoption is driving SSI from theory to practice. The EU's eIDAS 2.0 regulation mandates that all EU member states offer digital identity wallets to citizens by 2026—creating an SSI-aligned infrastructure for 450 million people. The wallet architecture supports selective disclosure (proving you're over 18 without revealing your birthdate) and cross-border verification. Similar programs are advancing in Canada, South Korea, and India's Aadhaar-linked systems.

For the agentic web, SSI extends naturally to agent identity. When AI agents act on behalf of individuals—signing transactions, accessing services, presenting credentials—the agent needs a verifiable, delegated identity linked to its principal. SSI provides the framework: the human controls the master identity, delegates specific credentials to agents, and can revoke delegation at any time. This solves the agent authentication problem without requiring every service to maintain its own agent registry.