Online, I am Sybil. So are you. You have no digital representation of your individual identity. Rather, you have various identities, disconnected and spread out among the administrative domains of the various services you use.

An independent identity is a prerequisite to being able to act independently. When we are everywhere, we are nowhere. We have no independent identity and are thus constantly subject to the intervening administrative identity systems of the various service providers we use.

Building a self-sovereign identity system changes that. It allows individuals to act and interact as themselves. It allows individuals to have more control over the way they are represented and thus seen online. As the number of things that intermediate our lives explodes, having a digital identity puts you at the center of those interchanges. We gain the power to act instead of being acted upon.

This is why I believe the discussion of online privacy sells us short. Being self-sovereign is about much more than controlling how my personal data is used. That's playing defense and is a cheap substitute for being empowered to act as an individual. Privacy is a mess of pottage compared to the vast opportunities that being an autonomous digital individual enables.

Technically, there are several choice for implementing a self-sovereign identity system. Most come down to one of three choices:

• a public, permissionless distributed ledger (blockchain)
• a public, permissioned distributed ledger
• a private, permissioned distributed ledger¹

Public or private refers to who can join—anyone can join a public ledger. A public system allows anyone to get an identity on the ledger. Private system restrict who can join. I owe this categorization to Jason Law.

Permissioned and permissionless refers to how the ledger's validators are chosen. As I discussed in Properties of Permissioned and Permissionless Blockchains, these two types of ledgers provide a different emphasis on the importance of protection from censorship and protection from deletion. People of a more libertarian bent will prefer permissionless because of it's emphasis on protection from censorship while those who need to work within regulatory regimes will prefer permissioned.

We could debate the various benefits of each of these types of self-soveregn identity systems, but in truth they are all preferable to what we have today a each allows individuals to create and control identities independent of the various administrative domains with which people interact. In fact, I suspect that one or more instantiations of each these three types will exist in parallel to serve different needs. Unlike the physical world where we live in just one place, online, we can have a presence in many different worlds. People will use all of these systems and more.

Regardless of the choices we make, the principle that ought to guide the design of self-sovereign identity systems is respect for people as individuals and ensuring they have the ability to act as such.

In my discussion on the CompuServe of Things, I said:

"On the Net today we face a choice between freedom and captivity, independence and dependence."

I don't believe this is overstated. As more and more of our lives are intermediated by software-based systems, we will only be free if we are free to act as peers of these services. An independent identity is the foundation for that freedom to act.

1. A private, permissionless ledger is an oxymoron.