Privacy as a property of derivation, not of a custodian's promise.
I = (path, ciphertext, T, A, C)
A = A₁ ∪ A₂ ∪ ... ∪ Aₙ (any member resolves independently)
A = A₁ ∩ A₂ ∩ ... ∩ Aₙ (all members required, jointly)
Same tuple as the base Island. The addition: A is no longer
atomic — it is itself a set expression over kernel identities.
manifest(p | o, m, a) = x: existence at a path is contextual, not stored. See SpaceStructure._(secret) makes A a structural property of the path itself, enforced by decryption, not by a checked policy. See EncryptedAudiences.wrapSecretV1 over identityHash(K) extends single-owner A to union/intersection across kernels. See SetChemistry.
An Encrypted Semantic Island is what these three produce composed: a space
(manifest) whose audience (_) is a set expression
(union/intersection) over independent kernel identities.
T ⊥ A
Topology and audience are independent variables. The party holding
ciphertext at a given T is not, by that fact,
a member of A. Holding the bytes and deriving their meaning
are separate capabilities.
| Policy custody (ToS) | Encrypted Semantic Island | |
|---|---|---|
| readability | f(custodian intent) | f(key derivation) |
| T and A | same party | independent (T ⊥ A) |
| enforcement point | external checkpoint, bypassable | fused into decryption itself |
| failure mode | silent policy violation | decrypt failure |
| what changes behavior | trust in a promise | possession of derived key material |
T is not a kernel data structure; where ciphertext physically
lives remains external infrastructure. Constructing a union or intersection
A requires each principal's P256_pub in advance —
a key-distribution problem the kernel does not solve. Removing a member
from a union A requires re-encryption for backward secrecy;
intersection A requires out-of-band coordination to reassemble
shares. None of this is promise-based — all of it is a protocol dependency,
not a trust dependency on a custodian who already holds the plaintext.
For why this distinction matters in practice, not just in formalism: manifesto.html and The Byzantine Prompt.