Audit H4 (Alto). The embedded NATS has a single account with no per-subject
permissions, so any registered peer can subscribe to any subject — a cleartext
(ModeNATS) room's payload is readable by anyone who knows the subject.
A complete per-subject ACL derived from membership does not fit here: NATS
evaluates a connection's permissions once at connect time and never re-evaluates
them, but unibus clients connect-then-create/join-then-publish on one connection
(TestSecureBusEndToEnd). Static permissions would forbid the owner from
publishing to a room it just created; the dynamic reconnection model belongs to
the 0003 decentralization redesign. See dev/0004d-dataplane-acl.md.
Minimum defense implemented: Server.RequireEncryptedRooms (set by membershipd on
any non-loopback bind) refuses to create cleartext rooms, so every room on a
public deployment is end-to-end encrypted. Message CONTENT stays confidential
even with no subject isolation; residual traffic-metadata exposure is documented
and tracked for 0003.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
