## Summary
Apple SDK 27.1 device captures include authenticator extension data that
the current verifier rejects. Replace the general appattest dependency
with a private gateway module that verifies the complete original bytes,
frames enrollment and assertions separately, and accepts well-formed
optional extensions without SDK-specific length or flag allowlists.
The module retains established signature, P-256, CBOR, and
certificate-chain libraries. App identity, exact enrollment environment,
credential/key binding, nonce, challenge, and increasing-counter checks
remain enforced. Bounded parsing rejects ambiguous duplicate keys,
truncation, trailing data, and oversized inputs. Fixture helpers are
test-only. Adapted code retains both upstream MIT notices and source
provenance.
Category/version properties remain authenticated observations under the
chosen compatibility-release policy. This does not implement Apple's
additional distribution-category/version enforcement; introducing those
restrictions requires a separately defined deployment policy. The
[verification
contract](https://github.com/block/buzz/blob/app-attest-owned-verifier/docs/app-attest-compatibility.md)
records this and other limits.
Related: https://github.com/block/buzz/pull/8020 addresses assertion
extension handling. This change also covers enrollment extensions,
credential-key parsing, and certificate validation.
### Validation
- Gateway suites: 77 default tests and 79 personal-development tests
passed, plus startup policy and Clippy.
- Added signed enrollment/certificate, generated CBOR mutation,
maximum-counter, and PostgreSQL race/replay coverage. All 12 isolated
Postgres tests passed. Apple's historical fixture is tested
structurally, not accepted as a current enrollment. Positive synthetic
leaf certificates are generated at test time.
- Protected SDK 26.5/27.1 enrollments and assertions pass the verifier,
including the same key across SDK upgrades; development enrollment
rejects under production policy. Captures are personal-development
identities, not supported production-identity evidence.
- Full local CI passed Rust tests and reached 6,828 passing desktop JS
tests before an unchanged 10 ms focus-timer test failed; its five-test
file passed in isolation. The pre-push native suite had 3,421 passes and
an unchanged 300 ms child-PID test failure, also passing in isolation.
Prior ACP timing flakes and these unrelated hook exceptions do not waive
required CI.
- Windows CI exposed a missing system OpenSSL installation for the test
fixture generator. The test dependency now builds bundled OpenSSL; all
30 focused App Attest tests pass locally. [Current-head
CI](https://github.com/block/buzz/actions/runs/38636062347) passed,
including Windows Rust, PostgreSQL, and desktop integration tests.
- [Prior-head Codex
review](https://github.com/block/buzz/pull/8329#issuecomment-6177515598)
found no major issues. Carl subsequently identified a dropped
credential-length workaround; fixed in
[27f9f26](27f9f2624f),
with 34 focused/protected tests and Clippy passing. [Current-head Codex
review](https://github.com/block/buzz/pull/8329#issuecomment-6178361143)
found no major issues; physical iOS 26 testing was explicitly waived by
Tom on October 14, 2026. No iOS 26 device test was performed. The SDK
comparison used the same iOS 27.0.1 device, so it demonstrates
SDK-linked variation without establishing OS-version causation.
- Isolated candidate HTTP/device validation passed with separate
authority state and no APNs delivery: SDK 26.5 enrollment/delegation,
SDK 27.1 delegation with the exact same key and installation, and fresh
SDK 27.1 enrollment/delegation. Assertions changed from 37 to 102 bytes
across the upgrade; accepted counter increased from 1 to 3 and
delegation generation from 1 to 2. All three runs rejected tampering and
replay (401) and consumed challenges (404). Existing Buzz app builds
were preserved. No production rollout is included.
- Existing-installation validation passed against the current-head Dev
gateway: a guarded SDK 27.1 diagnostic reused the stored key and
installation, advanced the assertion counter from 88 to 89 and
delegation from 89 to 90, and published the existing active relay lease
at generation 9 (previously 8). Independent database reads confirmed the
changes and preserved key, epoch, and expiry. The original app build was
restored in place with current data and keys intact.
---------
Signed-off-by: Tom Brow <tomb@block.xyz>
