1.2: Understanding Core Concepts

Self-sovereign identity tells the core story of XIDs: why they exist and what they do. However, XIDs are built on a number of additional core concepts. They're all detailed in the Core Concepts documents and further summarized here.

All of the core concepts are useful for understanding XIDs, but you may particularly want to read the discussions of Data Minimization and the technologies for XIDs and Gordian Envelope.

Core Philosophies

Attestation & Endorsement Model. An attestation is a formal statement of something. Broadly, it can come in two forms: a self-attestation, which is a formal statement you make about yourself, and a peer endorsement, which is a formal statement that you make about something else. Attestations and endorsements are closely related to claims and credentials in the larger world of identity.

An attestation is most powerful if it's provable, partially or fully. Building out context for an attestation can also help in that. Beyond that, the value of an attestation ultimately depends on the reputation of the person making the attestation. Your self-attestations, beyond what can be proven, are only as strong as your reputation. Your peer endorsements ultimately lend your reputation to the people your endorse: if they prove incorrect, your reputation suffers.

Data Minimization. The concept behind data minimization is simple: you should disclose the minimal amount of data that you need to at any time. Making an age-restricted purchase is the traditional example: you shouldn't have to show your driver's license, which has lots of other personal information about you, you shouldn't even have to reveal your age, simply that your age is within the range that allows the purchase.

This isn't a philosophical question of privacy. Every bit of information that you reveal is dangerous. It might allow correlation, revealing something more than you intended. It might be used for purposes that you didn't intend. It might create possibilities for coercion. It might cause prejudice or disadvantage. And every bit of data that you reveal is potentially out there forever.

Elision Cryptography. One way to support Data Minimization is to selectively elide (remove) information from documents before you send them out, ensuring that what you send to each person only contains the information that you need to know.

Crypographic elision takes the next step: it preserves hashes of elided data so that you can later prove that the data was in a document, even after it is removed. If signatures are made across data hashes, rather than the data itself, then the signatures also remain valid. This allows for the creation of signed credentials that the credential holder can selectively elide to ensure Data Minimization.

The Fair Witness Approach. Another way to increase the value of Endorsements and other Attestation is by using the fair witness approach: you carefully attest to only what you can independently determine, you acknowledge any biases in the observation, you add context that's important to the observation, and you document it all as part of the Attestation.

Even if a fair-witness Attestation reveals bias, it can still be more valuable than an Attestation without that contextual information, because it allows the reader of the Attestation to better assess what it actually means.

Key Management. Keys are what make the trustless world of cryptographic identities and digital assets go 'round. They're what control your identity and assets, and what you use to prove ownership of the same. Without the keys, you literally have nothing.

Key management is what ensures you maintain control of those things. Its built on a foundation of heterogeneity, meaning that you use different keys for different things, so that when you lose one, you don't lose everything. Beyond that, it requires key rotation and revocation as things change over time.

The Progressive Trust Life Cycle. In real life, trust is a progressive thing. When you meet someone and grow your relationship over years, you slowly extend new information to them, slowly learn new things about them, and so over time gain increasing trust of them (or possibly the opposite, depending on what you learn).

The progressive trust life cycle models real-world relationships as a life cycle of increased disclosure and trust. It's intended as a foundation for how digital relationships can be similarly modeled, in part by using the concept of Data Minimization. This replaces the all-or-nothing disclosure that is much more common on the 'net today.

Pseudonymous Trust Building. Revealing your identity can be dangerous. This has become very obvious in recent years when judges, politicians, and other people impacting the civil society of America have been targeted and even killed for what they said or did. One solution is to adopt a pseudonymous identity: a stable identity that is not associated with your real-world self.

The problem with pseudonymous identities is creating trust for them. However, that trust can be bootstrapped through a Progressive Trust Life Cycle that includes quality work, verifiable self-attestations, and contextual peer endorsements. Over time, a pseudonymous identity can gain as much trust as a real-world identity.

Public Participation Profiles. Public participation profiles are Pseudonymous identities that are created specifically so that the identity holder can engage in public projects.

There are risks to participation, as they can expose information that you hadn't intended, and managing your pseudonymous identity requires all of the care of any Pseudonymous identity. But there can also be rewards in good work done.

Core Technologies

Gordian Envelope. The Gordian Envelope is a "smart document" system that collects and displays data in a regularized, deterministic way. Its recursive design allows for the storage of great depths of information, while its self-describing foundation ensures that it's always possible to see what a Gordian Envelope is and what it contains.

One of the greatest strengths of Gordian Envelope is its use of Elision Cryptopgraphy. The holder of an envelope can practice Data Minimization by eliding any information in an envelope while maintaining any signatures on the envelope and any credentials it might hold.

XID. Obviously this whole course is about XIDs, Blockchain Commons' self-sovereign identifier. The XID core concept document briefly outlines what a XID is, what it contains, and how it's created.

XIDs are built on Gordian Envelope using a tight structure that limits what objects can be placed at the top level of an envelope to standardize and simplify their content.

Summary: Getting to the Core

Why XIDs? These core concepts explain some of the reasons:

_ They enable Pseudonymous Trust Building where you can build up a pseudonymous identity over time, including Public Participant Profiles for working on public projects. - They allow for Attestations and Endorsements to be attached to your identity, possibly using a Fair Witness Approach that will improve their trustworthiness. - They support _Data Minimization using Elision Cryptography ensures that allows the holder to decide what to reveal while ensuring that signed statements remain valid. - This allows a Progressive Trust Life Cycle where you reveal details over time, just like in the real world. - They support Key Management that enables the best practices of heterogeneity and rotation.

What's Next

You're now ready to begin §1.3: Creating Your First XID, to get your hands into the actual work of XIDs.