Refresh checkpoint with legacy vault hardening

CHECKPOINT-encryption.md

@@ -1,4 +1,4 @@
-# Checkpoint — Header-based CSP + navigation guards (2026-08-21)
+# Checkpoint — Legacy vault permission hardening (2026-08-21)
 
 A stopping point you can return to if this session is closed. Everything below was
 verified green at the moment this file was written.
@@ -6,12 +6,12 @@ verified green at the moment this file was written.
 ## Where things are
 
 - Project: `/home/avi/Projects/0_Nostr`
-- Git repo: `master` @ `4d4dfde` ("Enforce header-based CSP and block window open/navigation").
-  Before it: `6e627a3` (upload pick tokens), `4bde395` (IPC allowlist), then checkpoint
-  commits, on top of contact-aware feed (`a1445d1`) etc.
+- Git repo: `master` @ `4bd7660` ("Tighten permissions on leftover legacy vault files").
+  Before it: `4d4dfde` (CSP + navigation guards), `6e627a3` (upload pick tokens),
+  `4bde395` (IPC allowlist), on top of contact-aware feed (`a1445d1`) etc.
 - Working tree is **clean** apart from this checkpoint update, which is committed right after.
 
-## What was completed: security hardening items #1, #2 and #3
+## What was completed: security hardening items #1–#4
 
 Fixes from the 2026-08-21 security audit.
 
@@ -55,8 +55,23 @@ page could read+publish arbitrary local files to nostr.build. Now:
 - `setWindowOpenHandler`: all `target="_blank"` popups are denied; external links go to the
   system browser. Unknown schemes are denied without opening anything.
 
+**#4 Legacy vault permissions (`4bd7660`):**
+- The original CLI left `profiles_vault.json` files with default (often group-readable)
+  permissions containing plaintext keys. Now:
+  - On **every** startup, `load_vault()` calls the new `harden_stray_legacy_vaults()`
+    (`src/vault.rs`): each known legacy location is checked, and any file that parses as a
+    populated vault is chmod'd to 0600 — whether or not migration ever runs.
+  - During migration itself, the legacy file is tightened before the backup copy is made.
+  - Hardening is best-effort (`let _ =`) so odd filesystems can never break vault loading;
+    unparsable and keyless files are deliberately not touched.
+- One-time local cleanup done by hand in this session: repo-root `profiles_vault.json`
+  was chmod'd from 0664 → 0600.
+- New tests: recognised legacy vault tightened to 0600; unparsable file ignored; empty /
+  encrypted-but-populated vaults classified correctly.
+
 ## Commits
 
+- `4bd7660` "Tighten permissions on leftover legacy vault files" — src/vault.rs (+79/−3).
 - `4d4dfde` "Enforce header-based CSP and block window open/navigation" — main.ts + index.html.
 - `6e627a3` "Replace upload file paths with single-use pick tokens" — main.ts, api.ts,
   types.ts, AppProvider.tsx, ComposeScreen.tsx, fakeBackend.ts (+62/−27).
@@ -97,10 +112,11 @@ Manual protocol checks worth doing once:
 
 Remaining audit items in priority order:
 
-1. **Legacy vault perms** — repo-root `profiles_vault.json` is group-readable (0664);
-   chmod 600 / delete after confirming migration; auto-tighten during migration in `src/vault.rs`.
-2. **Write-race fixes** — create files with mode 0600 at creation time in `vault.rs`
-   (`write_restricted`, `backup_file`).
-3. **Zeroize** — wipe decrypted key material via the `zeroize` crate.
-4. Smaller: link-preview SSRF guard (block loopback/private IPs), signer pending-cap,
+1. **Write-race fixes** — create files with mode 0600 at creation time in `vault.rs`
+   (`write_restricted`, `backup_file` currently chmod after creating).
+2. **Zeroize** — wipe decrypted key material via the `zeroize` crate.
+3. Smaller: link-preview SSRF guard (block loopback/private IPs), signer pending-cap,
    NIP-46 secret echo check, backend request timeout.
+
+All four high/medium user-facing findings from the audit are now closed (#1 IPC allowlist,
+#2 upload tokens, #3 CSP + navigation, #4 legacy vault perms).