Self-Sovereign Identity (SSI)

SSI is organized around a trust triangle, with the issuer that signs a credential, the holder that keeps it in a wallet and the verifier that checks it, supported by a verifiable data registry for keys and status. Christopher Allen set out its principles in 2016, including control, portability, interoperability, consent and data minimization. Credentials live on the user's device rather than on central servers.

It cuts down silos and constant reverification, provides data minimization by design and enables cross-border portability of identity. It is the conceptual frame that gives the rest of the cluster its meaning. It is not a single standard but a paradigm realized through W3C DID Core, from 2022, and the verifiable credentials data model 2.0, a recommendation from 15 May 2025.

The EU eIDAS 2.0 regulation (Regulation EU 2024/1183, in force since May 2024) brings these principles into the single-market framework, and its EUDI Wallet adheres to them with selective disclosure. Microsoft Entra Verified ID and stacks such as walt.id, Veramo, Dock, Gataca and IOTA Identity implement SSI architectures. When that identity is bound and made verifiable on a blockchain, it becomes on-chain identity.