> In the first scenario, I have a pseudonymous interaction with someone/something and I simply want to ensure that every time I interact with that person/thing

> In the first scenario, I have a pseudonymous interaction with someone/something and I simply want to ensure that every time I interact with that person/thing it's the same one. > All of those things can be done without a centralised ledger. They simply require a public key that is signed and distributed appropriately. Who signs and distributes the key, and why do you trust them to do so? This sounds a lot like the CA model, which I am trying to avoid using. Even if you went without a CA and relied on TOFU semantics, using the blockchain to distribute your public key is still a better choice than sending it over the wire to each requester because (1) when creating my name/pubkey pair, I will notice very quickly if the (jude-, pubkey) record in the blockchain is wrong, and immediately claim a different username; (2) once (jude-, pubkey) is published in the blockchain, it is extremely hard to change, so our adversary can't send you a different public key if you're on the same blockchain as me; (3) it is extremely hard for an adversary to make a separate plausible blockchain with the wrong (jude-, pubkey) transaction, since that would require a tremendous amount of CPU time to calculate all the necessary partial double-SHA256 preimages in order to re-write the transaction history back to the block where I registered (jude-, pubkey). > I will also add to this scenario the situation where you actually need to know the real identity of the pseudonymous entity (say if you are a bank). This requires a central authority who can verify the identity (this is required in every case), and that the central authority signs keys appropriately and makes those signatures available. I think this is a different problem than what I was trying to solve. It sounds like you want to have a high degree of confidence that the DNS name "ibm.com" points to web servers belonging to the actual IBM, and not a squatter or phisher. If so, then I agree that a blockchain will not help you there. The problem I've been trying to solve is using my out-of-band knowledge that "ibm.com" is the name for IBM's servers to obtain IBM's public key, without having to trust DNS, a CA, or some other centralized entity. I apologize that this was not clear earlier. > Shall we call them Tarou Sukuki 1, 2 and 3? Why not let them choose their own globally-unique names, and use a first-to-claim policy to resolve collisions?