Blockchain Commons

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Self-sovereign identity (SSI) is identity that preserves your autonomy and your control. You hold your identity, and you can move your identity among services. You interact with other entities as a peer. You can make claims about your identity and about other entities, and they can make claims about you. Ultimately, though, you get to decide which claims are tightly attached to your identity, and which are not.

W3C’s DID v1.0 was an attempt to create a specification for SSI that we contributed to. XIDs are a newer take on SSI that we think conforms better to the original intent of the self-sovereign identity movement.

Why is Self-Sovereign Identity Important?

If your digital identity is controlled by a corporation (like Meta) or by a government (like the USA), then you are ultimately a digital serf. You don’t control the persona that you create online, and it could be taken from you in a moment. All your social networking, all your reputation building, and all your permissions on systems, in repos, and in communities could be gone in an instant. This matters, because the digital world is becoming the public square of the 21st century. If it’s taken from you, many opportunities are snatched away as well.

Self-sovereign identity ensures that can’t happen by advocating for an identity that you can create, hold, and modify without external control. You decide how your identity is presented, who gets to see it, and what it contains. This grants you the same rights and ability to represent yourself online that you have in the physical world, and so ensures that you don’t lose rights as the reach of the digital world increases.

How Does Self-Sovereign Identity Work

The 2016 introduction of SSI introduced ten principles to define self-sovereign identity:

  1. Existence. Users must have an independent existence.
  2. Control. Users must control their identities.
  3. Access. Users must have access to their own data.
  4. Transparency. Systems and algorithms must be transparent.
  5. Persistence. Identities must be long-lived.
  6. Portability. Information and services about identity must be transportable.
  7. Interoperability. Identities should be as widely usable as possible.
  8. Consent. Users must agree to the use of their identity.
  9. *Minimalization.8 Disclosure of claims must be minimized.
  10. Protection. The rights of users must be protected.

(These principles are being updated for 2026 as part of the Revisiting SSI project.)

The technical specifics of SSI are less important than meeting the needs of these principles. However, these principles can also be seen in different ways, through different lenses. Principal Authority is another way to look at SSI: it says that a Principal has the ultimate authority over their identity. At Blockchain Commons, we also define SSI through architectural principles such as The Gordian Principles and the needs for [Data Minimization], [Elision Cryptography], [Progressive Trust], and [Pseudonymous Trust Building].

The Blockchain Stack

A lot of Blockchain Commons’ early work supported the safe and resilient control of digital assets. However, that was done to ultimately support the creation of a new generation of self-sovereign identity. Here’s how many of our technologies stack up to SSI (and build atop it).

Data Format Technologies:

  • CBOR - A concise, structured, self-identifying binary format.
  • dCBOR - A deterministic version of CBOR.
  • UR - A text encoding of CBOR.
  • Envelope - A capstone technology built on dCBOR and storable as a UR. This data storage format provides elision and encryption abilities needed for robust SSI.

Signature System Technologies:

  • Provenance Marks - A hash chain, which allows you to have multiple versions of an identity and show which is the most up-to-date.

Data Resilience Technologies:

  • SSKR - A way to back up your identity’s keys.
  • CSR - A way to collaboratively back up your identity’s keys.
  • CKM - A way to collaborative create an identity’s keys.

Identity Technologies:

Identity Communication:

  • Clubs - A self-sovereign way to share news or other information.
  • Garner - A self-sovereign way to share identity documents.

Introduction:

The Dangers of Overidentification:

Self-Sovereign Computing:

SSI Models:

Self-Sovereign Use Case: