fix(auth): redact non-OAuth credential secrets from the auth request event

src/google/adk/auth/auth_handler.py

@@ -50,12 +50,28 @@ def _normalize_oauth_scopes(
 def _credential_without_client_secret(
     credential: AuthCredential | None,
 ) -> AuthCredential | None:
-  """Returns a copy of credential with the OAuth2 client secret removed."""
+  """Returns a copy of credential with the agent's own secrets removed.
+
+  The auth request is sent to the client and stored in the session, so no
+  secret that belongs to the agent may travel in it. The OAuth2 client secret
+  is one such secret; an API key, an HTTP Basic password, and a service account
+  private key are the agent's too. They are re-supplied from the tool config
+  when the credential is exchanged.
+  """
   if credential is None:
     return None
   redacted = credential.model_copy(deep=True)
   if redacted.oauth2 is not None:
     redacted.oauth2.client_secret = None
+  if redacted.api_key is not None:
+    redacted.api_key = None
+  if redacted.http is not None and redacted.http.credentials is not None:
+    redacted.http.credentials.password = None
+  if (
+      redacted.service_account is not None
+      and redacted.service_account.service_account_credential is not None
+  ):
+    redacted.service_account.service_account_credential.private_key = None
   return redacted
 
 

src/google/adk/workflow/utils/_workflow_hitl_utils.py

@@ -164,12 +164,12 @@ def _build_auth_message(auth_config: AuthConfig) -> str:
 
 
 def _without_client_secret(auth_config: AuthConfig) -> AuthConfig:
-  """Returns a copy of the auth config with the OAuth client secret removed.
+  """Returns a copy of the auth config with the agent's secrets removed.
 
-  The auth request is handed to the caller, which needs the authorization uri
-  and the state to complete the flow but never the developer's client secret.
-  The secret stays on this side and is supplied again when the response comes
-  back.
+  The caller needs the authorization uri and the state to complete the flow but
+  never the agent's own secrets: the OAuth2 client secret, an API key, an HTTP
+  Basic password, or a service account private key. They are re-supplied from
+  the node config when the credential is used.
 
   Args:
     auth_config: The auth configuration for the node.
@@ -179,8 +179,19 @@ def _without_client_secret(auth_config: AuthConfig) -> AuthConfig:
       without_secret.raw_auth_credential,
       without_secret.exchanged_auth_credential,
   ):
-    if credential and credential.oauth2:
+    if not credential:
+      continue
+    if credential.oauth2:
       credential.oauth2.client_secret = None
+    if credential.api_key is not None:
+      credential.api_key = None
+    if credential.http and credential.http.credentials:
+      credential.http.credentials.password = None
+    if (
+        credential.service_account
+        and credential.service_account.service_account_credential
+    ):
+      credential.service_account.service_account_credential.private_key = None
   return without_secret
 
 

tests/unittests/auth/test_auth_handler.py

@@ -450,7 +450,13 @@ def test_non_oauth_scheme(self):
     handler = AuthHandler(config)
     result = handler.generate_auth_request()
 
-    assert result == config
+    # api key is stripped from the client-facing request; everything else stays.
+    assert result.raw_auth_credential.api_key is None
+    assert result.exchanged_auth_credential.api_key is None
+    expected = config.model_copy(deep=True)
+    expected.raw_auth_credential.api_key = None
+    expected.exchanged_auth_credential.api_key = None
+    assert result == expected
 
   def test_with_existing_auth_uri(self, auth_config_with_exchanged):
     """Test when auth_uri already exists in exchanged credential."""
@@ -926,3 +932,54 @@ async def test_successful_token_exchange(
     assert result.oauth2.access_token == "mock_access_token"
     assert result.oauth2.refresh_token == "mock_refresh_token"
     assert result.auth_type == AuthCredentialTypes.OAUTH2
+
+
+def test_generate_auth_request_redacts_api_key():
+  """A non-OAuth API key must not survive into the client-facing auth request."""
+  auth_config = AuthConfig(
+      auth_scheme=APIKey(**{"in": APIKeyIn.header}, name="X-API-Key"),
+      raw_auth_credential=AuthCredential(
+          auth_type=AuthCredentialTypes.API_KEY,
+          api_key="super-secret-api-key",
+      ),
+  )
+
+  prepared = AuthHandler(auth_config).generate_auth_request()
+
+  assert prepared.raw_auth_credential.api_key is None
+
+
+def test_generate_auth_request_redacts_service_account_private_key():
+  """A service account private key must not survive into the auth request."""
+  from google.adk.auth.auth_credential import ServiceAccount
+  from google.adk.auth.auth_credential import ServiceAccountCredential
+
+  auth_config = AuthConfig(
+      auth_scheme=APIKey(**{"in": APIKeyIn.header}, name="X-SA"),
+      raw_auth_credential=AuthCredential(
+          auth_type=AuthCredentialTypes.SERVICE_ACCOUNT,
+          service_account=ServiceAccount(
+              service_account_credential=ServiceAccountCredential(
+                  type="service_account",
+                  project_id="p",
+                  private_key_id="kid",
+                  private_key="-----BEGIN PRIVATE KEY-----secret-----END PRIVATE KEY-----",
+                  client_email="a@p.iam.gserviceaccount.com",
+                  client_id="1",
+                  auth_uri="https://accounts.google.com/o/oauth2/auth",
+                  token_uri="https://oauth2.googleapis.com/token",
+                  auth_provider_x509_cert_url="https://www.googleapis.com/oauth2/v1/certs",
+                  client_x509_cert_url="https://www.googleapis.com/robot/v1/x",
+                  universe_domain="googleapis.com",
+              ),
+              scopes=["https://www.googleapis.com/auth/cloud-platform"],
+          ),
+      ),
+  )
+
+  prepared = AuthHandler(auth_config).generate_auth_request()
+
+  assert (
+      prepared.raw_auth_credential.service_account.service_account_credential.private_key
+      is None
+  )