> For the complete documentation index, see [llms.txt](https://docs.empe.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.empe.io/understand/self-sovereign-identity.md).

# Self-Sovereign Identity

Empeiria's End-to-End Verifiable Data Infrastructure (EVDI) builds on the foundation of Self-Sovereign Identity (SSI), expanding its utility and enabling wider adoption.

SSI is a concept in digital identity, where individuals have full ownership and control over their personal identity information. Unlike traditional identity systems relying on centralized authorities, SSI allows users to own, manage, and share their data. This approach enhances privacy, security, and user autonomy by enabling individuals to authenticate themselves without depending on external entities.

In practice, the issuing, holding, and verifying of credentials in this platform happen off-chain: identities are expressed as Decentralized Identifiers (DIDs), credentials are protected by cryptographic signatures, and minimal disclosure is achieved through selective-disclosure techniques. Personal data stays in the holder's wallet, and verification is cryptographic.

This platform issues and verifies credentials off-chain with `did:web` and `did:key`. The `did:empe` method and EMPE blockchain are separate components of the wider Empeiria ecosystem — see [EVDI Architecture](/understand/intro.md).

## Key Features of SSI <a href="#id-37e1" id="id-37e1"></a>

Here are the key features and principles of SSI:

* **User-Centric:** In SSI, users have access and control over their identity data. They can decide what information to share, with whom, and for how long.
* **Privacy-Enhancing:** SSI is designed to prioritize privacy. Using cryptographic selective-disclosure techniques (SD-JWT), a holder can prove specific facts—such as a single claim from a credential—while keeping the rest of their data hidden. Disclosure of claims is minimized so users reveal only what each interaction requires.
* **Decentralized:** Traditional identity systems are controlled by central authorities, while SSI is built on decentralized principles. Identities are expressed as DIDs, the holder keeps all their data within the wallet, and no central registry sits between issuer, holder, and verifier.
* **Interoperable:** SSI systems aim to be universally applicable, allowing users to use their identity across different services and platforms without separate credentials.
* **Secure:** These systems use advanced cryptographic techniques—digital signatures over each credential—so that identity data is tamper-evident and can be verified independently, without contacting the original issuer.
* **Consent-Based:** Any sharing of personal data in SSI systems is based on the user's explicit consent, providing greater control over personal data.
* **Portable:** Users can carry their identity across different platforms and services without depending on a single provider.
* **Transparent:** The protocols and software are open, so anyone can inspect how identity data is handled and independently verify that the system behaves as claimed.


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