> Is the intention that E2EE have a separate, parallel account recovery mechanism with more difficult requirements?

I'm not sure the wording here is helpful.

Let's start with a simple diagram: https://github.com/fedi-e2ee/public-key-directory-specificat... (see the first one)

A single Public Key Directory will serve many hosts. (You can further add replication and cross-directory checkpointing between directories, to ensure the whole network is transparent, but that's not our concern right now.)

If a host decides to misbehave, there's an independently hosted record of every change to the state machine that maps Actor IDs to public keys. This state machine is backed by a Merkle tree, which includes a proof of inclusion for every change to its state, thereby making it an append-only ledger.

In my design, you don't have to trust the hosts' admins to behave, because the directory keeps them honest.

You also don't have to trust as single directory to behave, since its primary purpose is to be transparent and independently auditable.

If a user wants to revoke their key, they can, but it's an additional protocol message appended to the directory's transparency log.

If a user loses all their secret keys, one of two things can happen:

1. Their instance admin issues a BurnDown, which allows the user to enroll a new public key as if they were a new user.

2. If the user has issued a Fireproof message, the instance admin cannot issue a BurnDown, and the user is locked out of the protocol. This is a trade-off.

Users can move hosts. Users can publish auxiliary data (e.g., SSH public keys), if the extension for that key type is defined and enabled by the directory. Even an attacker with root access to the host cannot arbitrarily or selectively replace a user's public key with their own. With your suggestion, this substitution is trivial.

And that's basically how the system works. But that's not the focus of this blog post.

This blog post is how to solve the seemingly incompatible design goals of:

1. Offer userbase consistency verification for users' public keys.

2. Don't cryptographically inhibit an EU citizen's rights under Article 17 of the GDPR.

3. Don't introduce backdoors to the transparency log that allow them to perform the same trivial attack that your suggestion enables.