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Agent half of slice-7 close-out finalized: cross-repo wire-contract test (escrowUploadRequest mirrors the hub), v0.9.0 CHANGELOG entry + REPORT + CLAUDE version line. No secrets. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
58 lines
3.5 KiB
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58 lines
3.5 KiB
Markdown
# REPORT — Slice 7 close-out: PBS recovery-code escrow creation (v0.9.0) (2026-06-10)
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> Overwrite-latest report (most recent significant work only). Cumulative history lives in
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> [CHANGELOG.md](CHANGELOG.md). Implements the agent half of `TASK — Slice 7 close-out: PBS
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> recovery-code escrow creation`. The hub opaque-storage half is in `felhom.eu` (hub v0.8.0).
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## Outcome
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The first code that touches the PBS client encryption key `K` and introduces the customer recovery
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code `R`. Default posture is **zero-knowledge**: Felhom holds an opaque `R`-wrapped blob it cannot
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open; the customer holds `R`. The wrap→recover→restore round-trip was proven on a fenced throwaway
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before any code (`felhom.eu/documentation/tests/slice7-escrow-spike-findings.md`) — the `R`-recovered
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key restored a real encrypted snapshot.
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## Secret discipline (the overriding rule — held throughout)
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- `R`: `crypto/rand`, ≥128 bits, surfaced **exactly once** (selftest stdout), **never** logged,
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persisted, committed, or in this report. The wrap pty's echoed passphrase is **discarded** (F-A2).
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- `K`: read by location, **never modified** (Wrap operates on a copy; the live key file is
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byte-unchanged — asserted live by sha256), never logged.
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- The blob is opaque ciphertext; the hub stores bytes and never decrypts.
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## What landed (`internal/escrow`)
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- **`Create`** → generate `R` (10 EFF-wordlist words ≈ 129 bits) → **Wrap** `K` under `R` via the
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PBS-native `proxmox-backup-client key change-passphrase --kdf scrypt`, driven over a **stdlib pty**
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(`x/sys/unix`; the command is TTY-only, spike F-A1) with **output discarded** (F-A2) → **self-verify**
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the blob unwraps back to `K` (fingerprint match) before shipping → return `R` SEPARATELY (so it
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can't be logged via the result) + the opaque blob.
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- **Opt-in outputs:** (b) `R`-wrapped offline copy (two-factor, no extra trust); (a) raw paperkey
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(single-factor, unrevocable — loud caveat).
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- **`--selftest=escrow-create`** (`-storage`/`-paperkey`/`-offline`/`-upload`): surfaces `R` once,
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prints the opaque blob's size/fingerprint/posture, and with `-upload` PUTs it to the hub
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(`/api/v1/hosts/{host_id}/escrow`, per-host key).
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- Config: `escrow{posture, pbs_storage_id}` (zero_knowledge default); `PBSEncKeyPath` (the `<id>.enc`).
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- Runtime dependency: the `proxmox-backup-client` CLI.
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## Tests
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`go test ./...` green; `-race` green on the build server (pure-Go parts). `R` entropy ≥128 /
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10-word format / 200-draw uniqueness; the agent→hub wire-contract key-set (mirrors the hub). The
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integration round-trip (wrap→unwrap fingerprint match, **wrong-`R` fails**, **live `K` byte-unchanged**,
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blob ≠ plaintext) is guarded to linux+`proxmox-backup-client` and exercised by the live selftest.
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## Live validation (demo-felhom)
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`--selftest=escrow-create -storage felhom-pbs`: `R` (10 words) surfaced **once** to stdout; blob
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**383 B opaque** (key fingerprint `01:36:e9…`, posture `zero_knowledge`, ~129-bit `R`);
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**self-verify** confirmed recoverability; the live `K` (`felhom-pbs.enc`) **sha256 byte-unchanged**;
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the exact `R` was **absent** from stderr and the agent journal. *(Upload to the hub validated after
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hub v0.8.0 deploy — see felhom.eu REPORT.)*
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## Deferred (stated, not built)
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Escrow **consumption / restore-mode serving** → slice 10 (host-loss DR; the spike pre-validated it).
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The **Felhom-holds-a-key** posture (the one dangerous topology cell) is documented (doc 03 §8a) and
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implemented only on an explicit customer opt-in. No secrets committed.
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