1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259 | """
Integrated PoC for the narrowed verifier pipeline.
This service composes the three mechanism-level PoCs used by the public
reference flow:
- canonical signed-schema verification
- atomic replay reservation / finalize / release
- verification-time destination revalidation against issuer state
"""
from __future__ import annotations
from dataclasses import dataclass
from datetime import datetime, timezone
from typing import Callable
from backend.app.services.payload_revalidation_poc import (
match_payload_to_verified_domains,
)
from backend.app.services.replay_guard_poc import InMemoryReplayGuard
from backend.app.services.signed_schema_poc import (
CertificateAuthorityRecord,
SignedQRCodeEnvelope,
USAGE_POLICY_ONE_TIME,
USAGE_POLICY_REUSABLE_PUBLIC,
USAGE_POLICY_TIME_LIMITED,
canonical_claims_sha256,
verify_signed_envelope,
)
@dataclass(frozen=True)
class IssuerVerificationState:
verified_domains: list[str]
allow_subdomains: bool = False
certificate_active: bool = True
certificate_revoked: bool = False
certificate_revocation_reason: str | None = None
@dataclass(frozen=True)
class NarrowedVerificationResult:
allowed: bool
stage: str
reason: str
usage_policy: str
canonical_claims_sha256: str | None
matched_rule: str | None
reservation_state: str | None
class NarrowedVerifierService:
"""
Compose the narrowed verification pipeline into one service contract.
"""
def __init__(
self,
replay_guard: InMemoryReplayGuard,
*,
now_fn: Callable[[], datetime] | None = None,
) -> None:
self._replay_guard = replay_guard
self._now_fn = now_fn or (lambda: datetime.now(timezone.utc))
def _parse_claim_timestamp(self, value: str) -> datetime:
normalized = value.strip()
if normalized.endswith("Z"):
normalized = normalized[:-1] + "+00:00"
return datetime.fromisoformat(normalized)
def _accepted_reason(self, usage_policy: str) -> str:
if usage_policy == USAGE_POLICY_ONE_TIME:
return (
"Signed schema verified, nonce consumed, and destination "
"matches the issuer's current verified state"
)
if usage_policy == USAGE_POLICY_TIME_LIMITED:
return (
"Signed schema verified, QR is inside its validity window, "
"and destination matches the issuer's current verified state"
)
return (
"Signed schema verified, reusable public QR remains issuer-approved, "
"and destination matches the issuer's current verified state"
)
async def verify_presented_code(
self,
envelope: SignedQRCodeEnvelope,
certificate: CertificateAuthorityRecord,
issuer_state: IssuerVerificationState,
*,
reservation_ttl_seconds: int = 5,
consumed_ttl_seconds: int = 60,
) -> NarrowedVerificationResult:
"""
Verify a presented signed code against schema, replay rules, and the
issuer's current destination state.
"""
claims_digest = canonical_claims_sha256(envelope.claims)
usage_policy = envelope.claims.usage_policy
now = self._now_fn()
schema_decision = verify_signed_envelope(envelope, certificate)
if not schema_decision.allowed:
return NarrowedVerificationResult(
allowed=False,
stage="signed_schema",
reason=schema_decision.reason,
usage_policy=usage_policy,
canonical_claims_sha256=claims_digest,
matched_rule=None,
reservation_state=None,
)
if issuer_state.certificate_revoked:
reason = "Certificate is revoked"
revocation_reason = (
issuer_state.certificate_revocation_reason.strip()
if issuer_state.certificate_revocation_reason
else ""
)
if revocation_reason:
reason = (
f"{reason}: {revocation_reason}"
)
return NarrowedVerificationResult(
allowed=False,
stage="certificate_status",
reason=reason,
usage_policy=usage_policy,
canonical_claims_sha256=claims_digest,
matched_rule=None,
reservation_state=None,
)
if not issuer_state.certificate_active:
return NarrowedVerificationResult(
allowed=False,
stage="certificate_status",
reason="Certificate is not currently active for verification",
usage_policy=usage_policy,
canonical_claims_sha256=claims_digest,
matched_rule=None,
reservation_state=None,
)
issued_at = self._parse_claim_timestamp(envelope.claims.issued_at)
expires_at = self._parse_claim_timestamp(envelope.claims.expires_at)
if now < issued_at:
return NarrowedVerificationResult(
allowed=False,
stage="time_window",
reason="Credential is not yet valid",
usage_policy=usage_policy,
canonical_claims_sha256=claims_digest,
matched_rule=None,
reservation_state=None,
)
if now >= expires_at:
return NarrowedVerificationResult(
allowed=False,
stage="time_window",
reason="Credential has expired",
usage_policy=usage_policy,
canonical_claims_sha256=claims_digest,
matched_rule=None,
reservation_state=None,
)
if usage_policy in {
USAGE_POLICY_REUSABLE_PUBLIC,
USAGE_POLICY_TIME_LIMITED,
}:
payload_decision = match_payload_to_verified_domains(
envelope.claims.payload,
issuer_state.verified_domains,
allow_subdomains=issuer_state.allow_subdomains,
)
if not payload_decision.allowed:
return NarrowedVerificationResult(
allowed=False,
stage="payload_revalidation",
reason=payload_decision.reason,
usage_policy=usage_policy,
canonical_claims_sha256=claims_digest,
matched_rule=payload_decision.matched_rule,
reservation_state="not_required",
)
return NarrowedVerificationResult(
allowed=True,
stage="accepted",
reason=self._accepted_reason(usage_policy),
usage_policy=usage_policy,
canonical_claims_sha256=claims_digest,
matched_rule=payload_decision.matched_rule,
reservation_state="not_required",
)
owner_token = await self._replay_guard.try_reserve(
envelope.claims.nonce,
reservation_ttl_seconds=reservation_ttl_seconds,
)
if not owner_token:
return NarrowedVerificationResult(
allowed=False,
stage="replay_guard",
reason="Nonce is already reserved or consumed",
usage_policy=usage_policy,
canonical_claims_sha256=claims_digest,
matched_rule=None,
reservation_state="blocked",
)
payload_decision = match_payload_to_verified_domains(
envelope.claims.payload,
issuer_state.verified_domains,
allow_subdomains=issuer_state.allow_subdomains,
)
if not payload_decision.allowed:
released = await self._replay_guard.release(envelope.claims.nonce, owner_token)
return NarrowedVerificationResult(
allowed=False,
stage="payload_revalidation",
reason=payload_decision.reason,
usage_policy=usage_policy,
canonical_claims_sha256=claims_digest,
matched_rule=payload_decision.matched_rule,
reservation_state="released" if released else "release_failed",
)
finalized = await self._replay_guard.finalize(
envelope.claims.nonce,
owner_token,
consumed_ttl_seconds=consumed_ttl_seconds,
)
if not finalized:
return NarrowedVerificationResult(
allowed=False,
stage="replay_guard",
reason="Reservation could not be finalized",
usage_policy=usage_policy,
canonical_claims_sha256=claims_digest,
matched_rule=payload_decision.matched_rule,
reservation_state="finalize_failed",
)
return NarrowedVerificationResult(
allowed=True,
stage="accepted",
reason=self._accepted_reason(usage_policy),
usage_policy=usage_policy,
canonical_claims_sha256=claims_digest,
matched_rule=payload_decision.matched_rule,
reservation_state="consumed",
)
|