4/n: Remove challenge from choose/confirm, use new path

Biometric enrollment will not request a Gatekeeper HAT during
initial credential setup or credential confirmation anymore.
Instead, it is broken down into the following steps now.

Bug: 161765592

1) Request credential setup / confirmation to return a
   Gatekeeper Password
2) Biometric enrollment will generate a challenge
3) Biometric enrollment will request LockSettingsService to
   verify(GatekeeperPassword, challenge), and upon verification,
   the Gatekeeper HAT will be returned.

Since both LockSettingsService and Biometric enroll/settings
make use of biometric challenges, this allows us to make the
challenge ownership/lifecycle clear (vs. previously, where
LockSettingsService has no idea who the challenge belongs to).

Exempt-From-Owner-Approval:For files not owned by our team,
(StorageWizard), this change is just a method rename

Test: RunSettingsRoboTests

Run the following on face/fingerprint devices
Test: Remove credential
      adb shell am start -a android.app.action.SET_NEW_PASSWORD
      Set up credential + fingerprint
Test: Remove credential,
      adb shell am start -a android.settings.FINGERPRINT_SETTINGS
      This tests the ChooseLock* logic in FingerprintSettings
Test: Set up credential,
      adb shell am start -a android.settings.FINGERPRINT_SETTINGS
      This tests the ConfirmLock* logic in FingerprintSettings
Test: Remove device credential, enroll fingerprint/face. Succeeds.
      This tests the ChooseLock* returning SP path from
      BiometricEnrollIntro
Test: With credential and fingerprint/face enrolled, go to
      fingerprint/face settings and enroll. This tests the
      ConfirmLock* path in Fingerprint/FaceSettings
Test: Remove device credential, enroll credential-only, enroll
      fingerprint/face separately. Succeeds. This tests the
      ConfirmLock* returning SP path in BiometricEnrollIntro
Test: In SUW, set up credential, then biometric. This tests
      the ChooseLock* path in SUW
Test: In SUW, set up credential, go back, then set up biometric.
      This tests the ConfirmLock* path in SUW

Change-Id: Idf6fcb43f7497323d089eb9c37125294e7a7f5dc

src/com/android/settings/biometrics/BiometricUtils.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.biometrics;
+
+import android.app.Activity;
+import android.content.Context;
+import android.content.Intent;
+
+import com.android.internal.widget.LockPatternUtils;
+import com.android.settings.password.ChooseLockSettingsHelper;
+
+/**
+ * Common biometric utilities.
+ */
+public class BiometricUtils {
+    /**
+     * Given the result from confirming or choosing a credential, request Gatekeeper to generate
+     * a HardwareAuthToken with the Gatekeeper Password together with a biometric challenge.
+     *
+     * @param context Caller's context
+     * @param result The onActivityResult intent from ChooseLock* or ConfirmLock*
+     * @param userId User ID that the credential/biometric operation applies to
+     * @param challenge Unique biometric challenge from FingerprintManager/FaceManager
+     * @return
+     */
+    public static byte[] requestGatekeeperHat(Context context, Intent result, int userId,
+            long challenge) {
+        final byte[] gkPassword = result.getByteArrayExtra(
+                ChooseLockSettingsHelper.EXTRA_KEY_GK_PW);
+        if (gkPassword == null) {
+            throw new IllegalStateException("Gatekeeper Password is null!!");
+        }
+
+        final LockPatternUtils utils = new LockPatternUtils(context);
+        return utils.verifyGatekeeperPassword(gkPassword, challenge, userId).getGatekeeperHAT();
+    }
+
+    public static boolean containsGatekeeperPassword(Intent data) {
+        if (data == null) {
+            return false;
+        }
+        return data.getByteArrayExtra(ChooseLockSettingsHelper.EXTRA_KEY_GK_PW) != null;
+    }
+}