The relay files a key-log leaf under an account's fnid once it has one, and
under `local:<audience>/<user_id>` before that. The subject is inside the
hashed bytes, so a verifier that does not know the address cannot recompute the
leaf — and enforcement refused honest keys from any account that had claimed an
identity. A false positive on a real conversation is how a security setting
gets switched off and left off, so this is the half that decides whether the
feature is usable at all.
No relay change was needed. `GET /e2e/account/identity/{handle}` already
resolves a handle to an address, unauthenticated, and the buddy list already
carries the handle. The contact record now learns the address once and pins it
beside the identity keys, and `enforceKeyLog` recomputes against the pinned one
by default.
⚠️ **Pinned, not looked up per check**, and that is the entire point. Reading it
fresh each time would let a relay that wants to substitute a key simply also
change the name it files that key under, and every verification would agree
with the new answer. Recomputing against the address this contact has always
had is what makes the check about a person rather than about whatever the relay
says today.
First contact is still trust-on-first-use. Taking the relay's word once is not
a check; what it buys is that every later answer has to match it, and the
safety number is what covers the first sighting.
🔴 A CHANGED address is an identity change, for a stronger reason than a
changed key: an fnid is derived from the account key, so a new address is not a
new device — it is a different account key, and therefore a different person.
Accepting a change re-resolves rather than keeping the old address, because if
the address is what changed, keeping it would leave every later check
recomputing against a name the account no longer publishes under, and honest
keys would stay refused for ever.
⚠️ An unreachable relay pins NOTHING rather than pinning "no address".
`rememberIdentity` does nothing once an address is pinned, so a wrong answer
would be permanent — and the next successful lookup would then read as the
address changing, which is the alarm, for a network blip.
Proven against relay1 in three states, because only all three make it legible:
refused with nothing pinned, accepted once the contact carries the right
address, and refused again with a wrong one — so what makes it pass is the
address being right, not the check having been loosened. A changed address is
asserted to come back CHANGED against the real relay too.
Tested: 100 engine, 65 client, none failing, live suites enabled.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
