We all maintain strong opinions about what identity means to us individually and in the context of a particular application. “Soulbound Tokens” (SBT), as first introduced in the DeSoc paper, are an important innovation, yet they fall short by being tied only to an account as opposed to an identity. The paper explains identity primitives as follows:

*               “Our key primitive is accounts, or wallets, that hold publicly visible,                non-transferable (but* possibly revocable-by-the-issuer) tokens. We refer to                the accounts as ‘Souls’ and tokens held by the accounts as ‘Soulbound                Tokens’ (SBTs).”

These accounts or wallets could refer to almost any container that holds information – blockchain accounts, a Web5 wallet or an implementation yet to be discovered – and we agree that it is helpful to think about identity this way. The DeSoc paper, however, attached “Soul” to an entity that distributes identity-related information as opposed to the human who owns the account or wallet and receives the information:

               “The Ethereum Foundation could be a Soul that issues SBTs to Souls who                attended a developer conference.”

The first foundational issue with this concept is what happens if access to a wallet is lost. A wallet could also be stolen or sold. Consider rotating wallets: Is Soul rotation a thing? In fairness, the co-authors clarified their views, and we now think SBTs can be more accurately described as “Community-bound Tokens.” 

In describing SBTs, the co-authors introduced the concept of community recovery with SBTs bound to the intersection of specific social circles, communities or groups. For example, if authors of academic papers were to receive SBTs, Vitalik could be uniquely identified, with the help of his co-authors, as the writer sitting at the intersection of a set of papers he co-wrote.

The second foundational issue is the transferability of tokens. Non-transferability is a very desirable property that should be on the top of the list of specifications when dealing with identity. It is key to the design of many reputation systems that rely on the continuity of the identity.

Viewing SBTs as community-bound tokens helps us understand how these tokens can be bound to a person even if they are transferable. Assuming the intersection of your social circles narrows down to a person, even if the SBTs get transferred, you will always be able to prove that you are you through your communities and claim the tokens back. This makes them in theory not appealing at all to any potential buyer. Transfers can still happen though and have disastrous consequences, even if recovery happens quickly after.

Non-transferability is a difficult problem to solve. Here’s an example: imagine a token is bound to a wallet held by Alice, and Alice sells her wallet to Bob. He would be able to impersonate Alice even though the token can not be transferred from her account. Interestingly, using Verified Credentials (VC) and Decentralized Identifiers (DIDs) do not solve this problem either.

So what if we take the view that a human IS the soul? Humanbound is a primitive that can be used to issue a token tied to a human instead of just a wallet. Although communities and social circles are part of what makes you who you are, in a way they are only a part of your identity. You might restart your life entirely – change your career and move to a different country – but this does not affect the ability for border control to identify you. For their purposes, you are the same person. Our different social circles also evolve with time and relying on them for securing your identity may be tedious in the future.

More on how Humanbound works here. We are excited to hear your thoughts! Head over to our Discord to participate in the conversation or drop us a note on Twitter.