fix(tls): accept hashed non-CA certificates during trust checks

scripts/check_ca_trust.py

@@ -30,9 +30,12 @@ def check_bundle(path: Path) -> None:
     """Raise on an unreadable, empty, malformed, or affected CA bundle."""
     context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
     context.load_verify_locations(cafile=str(path))
+    # A hashed OpenSSL directory can include valid non-CA certificates (for
+    # example Ubuntu's snakeoil server certificate). get_ca_certs() omits them;
+    # use the total X.509 count to distinguish these from an empty store.
+    if not context.cert_store_stats()["x509"]:
+        raise ValueError("no certificates")
     certificates = context.get_ca_certs(binary_form=True)
-    if not certificates:
-        raise ValueError("no CA certificates")
     blocked = {
         BLOCKED_ROOTS[fingerprint]
         for certificate in certificates

tests/fixtures/ca-trust/README.md

@@ -1,5 +1,5 @@
 # CA trust regression fixtures
 
-The public CA certificates embedded in `tests/test_ca_trust.py` exercise the October 2026 eMudhra trust-store check. They contain no private keys. `emsign-g3.pem` and `aaa.pem` are the incident's affected trust anchors; `emsign-g1.pem` is an unaffected emSign anchor that must remain usable. The test creates temporary PEM files from these public constants. The certificate fingerprints are the factual identity of each fixture.
+The public certificates embedded in `tests/test_ca_trust.py` exercise the October 2026 eMudhra trust-store check. They contain no private keys. `emsign-g3.pem` and `aaa.pem` are the incident's affected trust anchors; `emsign-g1.pem` is an unaffected emSign anchor that must remain usable. `localhost-leaf.pem` is a synthetic self-signed Ed25519 server certificate with `CA:FALSE`, generated solely to reproduce hashed non-CA certificates found in Ubuntu's OpenSSL directory; its private key was discarded. The test creates temporary PEM files from these public constants. The certificate fingerprints are the factual identity of each fixture.
 
 Sources: the [incident root list](https://emudhra.we-have-a-problem.com/roots.json) and the public Mozilla root certificates distributed in Debian's `ca-certificates` package. Behavioral chain verification should also cover the incident site's separate [twelve published server chains](https://emudhra.we-have-a-problem.com/chains.zip).

tests/test_ca_trust.py

@@ -75,6 +75,20 @@ class CATrustTests(unittest.TestCase):
             self.assertEqual(result, 1)
             self.assertIn("emSign ECC Root CA - G3", errors.getvalue())
 
+    def test_hashed_non_ca_certificate_does_not_reject_clean_store(self):
+        # Ubuntu's OpenSSL directory can also hash ssl-cert-snakeoil.pem.
+        # A valid server certificate has no CA entries in get_ca_certs().
+        with tempfile.TemporaryDirectory() as tmp:
+            directory = Path(tmp)
+            (directory / "ce275665.0").symlink_to(self.fixtures / "localhost-leaf.pem")
+            defaults = ssl.get_default_verify_paths()._replace(
+                cafile=str(self.fixtures / "emsign-g1.pem"), capath=str(directory)
+            )
+            with patch.object(checker.ssl, "get_default_verify_paths", return_value=defaults), patch.dict(
+                os.environ, {defaults.openssl_capath_env: str(directory)}
+            ), contextlib.redirect_stdout(io.StringIO()):
+                self.assertEqual(checker.main(["--system"]), 0)
+
     def test_multiple_ca_directories_are_all_checked(self):
         with tempfile.TemporaryDirectory() as tmp:
             clean, stale = Path(tmp) / "clean", Path(tmp) / "stale"
@@ -96,6 +110,16 @@ class CATrustTests(unittest.TestCase):
 
 # Public Mozilla CA certificates; provenance: tests/fixtures/ca-trust/README.md.
 PUBLIC_CERTIFICATES = {
+    'localhost-leaf.pem': """-----BEGIN CERTIFICATE-----
+MIIBOTCB7KADAgECAhRcVxnOQNEFWf92K4dm4I8ChyjVMzAFBgMrZXAwFDESMBAG
+A1UEAwwJbG9jYWxob3N0MB4XDTI2MTAyMTE4NTgwN1oXDTM2MTAxODE4NTgwN1ow
+FDESMBAGA1UEAwwJbG9jYWxob3N0MCowBQYDK2VwAyEARglphvNgp9qRCESLHnuu
+W8VC5urdZl+YgS+Ux1BoLryjUDBOMB0GA1UdDgQWBBSaEckyR/76lX3a5Ijh8B42
+oJwN1DAfBgNVHSMEGDAWgBSaEckyR/76lX3a5Ijh8B42oJwN1DAMBgNVHRMBAf8E
+AjAAMAUGAytlcANBAJkq9ayy+d4AUZnjhWM31rFke5DT+l9QFcPl34+dpVhqJV/L
+m4IpPHYagqrBRHn9Dv/C8qYyPBKnAwJRpNptsgw=
+-----END CERTIFICATE-----
+""",
     'aaa.pem': """-----BEGIN CERTIFICATE-----
 MIIEMjCCAxqgAwIBAgIBATANBgkqhkiG9w0BAQUFADB7MQswCQYDVQQGEwJHQjEb
 MBkGA1UECAwSR3JlYXRlciBNYW5jaGVzdGVyMRAwDgYDVQQHDAdTYWxmb3JkMRow