_verify_assertion_token now takes expected_host and rejects any token
whose bundle["host"] does not match — closing the cross-server replay
path where a token issued for server-a could have passed on server-b.
ServerState gains protected_host (default 127.0.0.1); k_server exposes
--protected-host CLI flag so operators declare which host they protect.
New abuse tests (unit + round-trip):
test_cross_server_replay_rejected
test_cross_server_replay_case_insensitive
test_roundtrip_cross_server_replay_rejected
test_roundtrip_cross_server_replay_accepted_on_correct_server
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Challenge is now SHA256(host|nonce) instead of SHA256(url|method|nonce).
A single card interaction authorises access to any path and method on the
gated domain, which is the intended granularity. Tests updated accordingly:
path/method rejection cases replaced with domain-level and tampered-host cases.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Each request to a gated endpoint now triggers a fresh FIDO2 assertion.
Challenge = SHA256(url|method|nonce) — bound to the specific resource.
The self-contained assertion bundle lets the server verify independently
without calling back to the phone.
- fido2_ops.dart: GetAssertionResult gains clientDataJson; getAssertion
accepts optional challenge override
- proxy_service.dart: _handleAuthGetToken accepts {url,method,nonce},
derives challenge, runs card assertion, returns b64url bundle
- filter_proxy.dart: _getAuthToken(uri, method) generates nonce and
passes binding fields to Component 2
- component3/phone.go: stateless GetTokenForRequest(url, method) —
no session caching, no expiry, one card touch per request
- component3/proxy.go: use GetTokenForRequest
- component3/main.go: remove --user flag (Component 2 picks enrolled user)
- k_server_app.py: _verify_assertion_token() — verifies path+method
match, challenge claim, and ECDSA-P256 signature; accepts both
legacy X-Proxy-Token and new Bearer assertion tokens
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Morten V. Christiansen