glm-5.2
d149932e2a
W1 (call/protocol/abort-cascade-wiring): wire AbortCascade into CallAdapter handle_stream for EVENT_ABORTED. W2 (core/endpoint-client-fingerprint): extract TLS client cert fingerprint in dispatch_quinn/dispatch_iroh. W3 (vault/mnemonic-debug-redaction): replace Mnemonic derive(Debug) with redacting impl. W4 (core/auth-apikey-resources, level: research): decide whether ApiKeyEntry should carry resources, then implement or drop from spec. review-post-impl-fixes gates on all four. Graph: 33 tasks, 12 gens.
110 lines
3.9 KiB
Markdown
110 lines
3.9 KiB
Markdown
---
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id: vault/mnemonic-debug-redaction
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name: Replace Mnemonic derive(Debug) with redacting impl to prevent seed phrase leak
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status: pending
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depends_on: []
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scope: single
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risk: low
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impact: isolated
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level: implementation
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---
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## Description
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`Mnemonic` (crates/alknet-vault/src/mnemonic.rs:35) currently derives
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`Debug`:
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```rust
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#[derive(Debug)]
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pub struct Mnemonic {
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inner: Bip39Mnemonic,
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phrase: String,
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}
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```
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The derived `Debug` prints both fields, including `phrase: "abandon
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abandon abandon ..."`. The crate's own module doc (mnemonic.rs:8) says
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"Seed material is protected with `Zeroize`" and the `Mnemonic::phrase()`
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accessor (line 82) warns "Handle with care — this is the root of trust
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for all derived keys." The `Zeroize + Drop` impls (lines 88–99) wipe
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the phrase from memory on drop — but `Debug` will happily hand the
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phrase to any `tracing::debug!`, `format!("{:?}")`, panic backtrace,
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or error-context printer that touches a `Mnemonic` value.
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This is inconsistent with the rest of the crate's secret handling:
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- `DerivedKey` has a custom redacting `Debug` (protocol.rs:48–56)
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printing `private_key: "[REDACTED]"`.
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- `EncryptionKey` has a custom redacting `Debug` (encryption.rs:132–139).
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- `Capabilities` has a redacting `Debug` (types.rs:112–118).
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- `Secret<T>` has a redacting `Debug` (types.rs:51–55).
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- `Mnemonic` ... derives `Debug` and prints the phrase.
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The root of trust should never have a `Debug` impl that can print it.
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A future debugging session that adds `tracing::debug!(?mnemonic, ...)`
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would land the seed phrase in a log file.
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### Resolution
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Replace `#[derive(Debug)]` with a manual impl that redacts, matching
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the pattern used for `DerivedKey`:
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```rust
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impl std::fmt::Debug for Mnemonic {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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f.debug_struct("Mnemonic")
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.field("phrase", &"[REDACTED]")
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.finish()
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}
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}
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```
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Also check `Seed` (mnemonic.rs:107–129) — it derives
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`#[derive(Clone, Zeroize)]` with `#[zeroize(drop)]` but does not derive
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`Debug`. Verify it has no `Debug` impl that prints `bytes`; if it does
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(or if a future `derive(Debug)` would), add a redacting impl there too.
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### Test
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Add a test asserting `format!("{:?}", mnemonic)` does not contain any
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word from the generated phrase. Pattern after
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`test_derived_key_debug_redacts_private_key` (protocol.rs:106–118):
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```rust
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#[test]
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fn test_mnemonic_debug_redacts_phrase() {
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let mnemonic = Mnemonic::generate(24).unwrap();
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let debug_output = format!("{:?}", mnemonic);
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assert!(
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debug_output.contains("[REDACTED]"),
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"Debug must show [REDACTED] for phrase, got: {debug_output}"
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);
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for word in mnemonic.phrase().split_whitespace() {
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assert!(
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!debug_output.contains(word),
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"Debug must not leak phrase word '{word}', got: {debug_output}"
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);
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}
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}
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```
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## Acceptance Criteria
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- [ ] `Mnemonic` no longer derives `Debug`; has a manual redacting `Debug` impl
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- [ ] `format!("{:?}", mnemonic)` contains `"[REDACTED]"` and no phrase word
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- [ ] `Seed` checked — either has no `Debug` impl, or has a redacting one
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- [ ] Unit test: `test_mnemonic_debug_redacts_phrase` passes
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- [ ] Existing tests still pass (`cargo test -p alknet-vault`)
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- [ ] `cargo clippy -p alknet-vault --all-targets` succeeds with no warnings
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## References
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- docs/reviews/004-post-implementation-sanity-check.md — W3 (full finding)
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- crates/alknet-vault/src/protocol.rs:48–56 — `DerivedKey` redacting `Debug` (pattern to follow)
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- crates/alknet-vault/src/encryption.rs:132–139 — `EncryptionKey` redacting `Debug`
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- crates/alknet-core/src/types.rs:51–55 — `Secret<T>` redacting `Debug`
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## Notes
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> Small fix, but eliminates a latent root-of-trust leak. The same
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> pattern (custom redacting `Debug`) is already established in three
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> other places in this codebase — this task brings `Mnemonic` in line. |