fix(auth): authenticate producer-signed decisions before authorization

Assistant: codex
Assistant-Model: gpt-6-astra
Assistant-Session: 01a140c4-354a-7823-8f0d-8f717397f786

tests/signature_support.py

@@ -0,0 +1,35 @@
+"""Native producer signing fixtures, never an authentication bypass."""
+import json
+import os
+from pathlib import Path
+import subprocess
+import pytest
+
+PUBLIC='IVL40Zt5HSRFMkLhXy6rbLfP-ntqXtMAl5YOBpiB2xI'
+
+@pytest.fixture(scope='session')
+def signature_tools(tmp_path_factory):
+    directory=tmp_path_factory.mktemp('signature-tools')
+    # Private writable build cache keeps tests runnable in the workspace sandbox.
+    env={**os.environ,'GOCACHE':os.environ.get('GOCACHE',str(directory/'cache'))}
+    root=Path(__file__).parents[1]/'verifier'
+    for name,package in [('verify','.'),('sign','./testsupport/signer')]:
+        subprocess.run(['go','build','-o',str(directory/name),package],cwd=root,env=env,check=True,timeout=120)
+    return directory
+
+
+def admit_tools(cfg, directory, tools):
+    trust={'schema':'secrets-engine.pdp-trust.v1','evaluator':'stub/local','mode':'standalone',
+           'policy_package':cfg.authorization_policy_package,'policy_version':cfg.authorization_policy_version,
+           'policy_package_digest':'sha256:'+'1'*64,'keys':{'testdata-ed25519':PUBLIC}}
+    path=directory/'pdp-trust.json';path.write_text(json.dumps(trust))
+    from dataclasses import is_dataclass, replace
+    if is_dataclass(cfg):
+        return replace(cfg,pdp_trust_file=path,pdp_verifier=tools/'verify')
+    cfg.pdp_trust_file=path;cfg.pdp_verifier=tools/'verify'
+    return cfg
+
+
+def sign_envelope(envelope,tools,next_key=False):
+    result=subprocess.run([str(tools/'sign')]+(['next'] if next_key else []),input=json.dumps(envelope),text=True,capture_output=True,check=True,timeout=3)
+    return json.loads(result.stdout)