Shared, not prescribed
CARLOS does not choose your security posture. It makes you declare it, in one published letter, and then refuses to place a workload on a host that is not trusted enough to hold what it holds.
S
Stateless
Holds no user data at all: a static file tree, or a binary with no persistent user state. There is nothing for a host to see.
carlosframework.com · rastrillo.org · carloku.com
A1
Host-blind
Keys live on the user's own devices; the instance never holds one that opens user content. The only residue is transport shape: who connects when, object sizes, timing. No content-derived identifiers at rest.
Slopbox — padded fixed-size blobs, encrypted filenames
A2
Host-blind, declared residue
Content sealed as in A1, plus an enumerated application-level residue that the app publishes in the open. An undeclared plaintext surface is a class violation regardless of intent, because the declaration is what makes the class auditable.
Keymail — routing headers · Kass — log timestamps · Eleven — thread membership · Woodstar
A/pub
Public by design
A host-blind app whose plaintext surfaces are public on purpose, listed one by one. A box hosting public posts learns nothing a browser would not.
Woodstar — public posts; blobs and direct messages stay sealed
B
Sealed single-tenant
Sealed everywhere it rests outside the live process: parked database, replica, blobs. The running instance holds a key in memory while awake, because unattended automation requires plaintext. A cold artifact leak yields nothing; a live-host compromise yields data.
Seapointish — the defining example
C
Host-sighted
Plaintext at rest as a deliberate, recorded decision: support visibility, SQL over personal data, payments. Confidentiality rests on operator policy and tenant isolation rather than on mathematics, and stated plainly rather than implied quietly.
Tito — the defining example