┌──────────────────────────────────────────┐
│  NUSEUM  ·  INSTITUTIONAL  SETTLEMENT    │
└──────────────────────────────────────────┘

[ ENCRYPTED_LANE ▸ CLIENT-SIDE AES-256-GCM ▸ server never sees plaintext ]

[ ENCRYPTED LANE · v0.1 · BYO-key ]

Send what we cannot read.

Files encrypt in the browser with AES-256-GCM under a key generated in your tab. We only ever store the ciphertext envelope, its sha256, and the audit row — the plaintext never leaves the browser.

SEAL · INSTITUTIONAL ENVELOPE

envelope · sha256

AES-256-GCM · browser-sealed

  ┌───────── SESSION_KEY ─────────┐
  │ alg ........... AES-256-GCM    │
  │ iv ............ 96-bit random  │
  │ key_source .... window.crypto  │
  │ key_at_rest ... NEVER          │
  └────────────────────────────────┘

▸ key (hex):
8c87153f2880aac2ee51eec125ac184a
f990a0e4b303ca14200f6c2c6ecad49a

[ WORKFLOW ▸ FILE → BRAID → SEAL → HASH → RECEIPT ]

5-second loop · mechanical_precision

[ EXHIBIT · ENCRYPTED_LANE_ENVELOPE · 5s loop ]file ▸ AES-GCM braid ▸ seal ▸ SHA-256 etch ▸ chain

[ DROP ▸ FILE ▸ ≤25 MB ▸ MIME-sniffed server-side ]

┌──────────────────────────────────────────────────────────┐ │ │ │ ▸ ATTACH FILE TO ENCRYPT │ │ │ │ file is hashed + AES-256-GCM sealed in this tab │ │ ciphertext + iv leave the browser │ │ plaintext never does │ │ │ └──────────────────────────────────────────────────────────┘

[ NEVER ▸ STORED ]

  ⨯ plaintext bytes
  ⨯ session key
  ⨯ derived material
  ⨯ filename mapping for non-receipted
  ⨯ logs of payload contents
  ─────────────────────────────────
  ✓ ciphertext + iv (envelope)
  ✓ envelope hash row
  ✓ uploader actor_id
  ✓ batch receipt reference

[ ENVELOPES ▸ this session ▸ 0 ]

▸ next batch receipt issues at top of next hour

  (empty — encrypt a file above to populate)

▸ DATA PROVENANCE — see deliverables/data-provenance.md for the full list of fields we deliberately do not collect. ▸ KMS — production tenants can bind envelopes to hardware-security-module keys (post-pilot).