src/com/android/settings/UserCredentialsSettings.java - LeafOS-Project/android_packages_apps_Settings - Gitiles

 /*
  * Copyright (C) 2015 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;

 import android.annotation.LayoutRes;
 import android.annotation.Nullable;
 import android.app.Dialog;
 import android.content.Context;
 import android.content.DialogInterface;
 import android.os.AsyncTask;
 import android.os.Bundle;
 import android.os.Parcel;
 import android.os.Parcelable;
 import android.os.Process;
 import android.os.RemoteException;
 import android.os.UserHandle;
 import android.os.UserManager;
 import android.security.Credentials;
 import android.security.IKeyChainService;
 import android.security.KeyChain;
 import android.security.KeyChain.KeyChainConnection;
 import android.security.KeyStore;
 import android.security.keymaster.KeyCharacteristics;
 import android.security.keymaster.KeymasterDefs;
 import android.util.Log;
 import android.util.SparseArray;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.TextView;

 import com.android.internal.logging.nano.MetricsProto.MetricsEvent;
 import com.android.internal.widget.LockPatternUtils;
 import com.android.settings.core.instrumentation.InstrumentedDialogFragment;
 import com.android.settingslib.RestrictedLockUtils;
 import com.android.settingslib.RestrictedLockUtils.EnforcedAdmin;

 import java.security.UnrecoverableKeyException;
 import java.util.ArrayList;
 import java.util.EnumSet;
 import java.util.List;
 import java.util.SortedMap;
 import java.util.TreeMap;

 import androidx.appcompat.app.AlertDialog;
 import androidx.fragment.app.DialogFragment;
 import androidx.fragment.app.Fragment;
 import androidx.recyclerview.widget.RecyclerView;

 public class UserCredentialsSettings extends SettingsPreferenceFragment
         implements View.OnClickListener {
     private static final String TAG = "UserCredentialsSettings";

     @Override
     public int getMetricsCategory() {
         return MetricsEvent.USER_CREDENTIALS;
     }

     @Override
     public void onResume() {
         super.onResume();
         refreshItems();
     }

     @Override
     public void onClick(final View view) {
         final Credential item = (Credential) view.getTag();
         if (item != null) {
             CredentialDialogFragment.show(this, item);
         }
     }

     @Override
     public void onCreate(@Nullable Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         getActivity().setTitle(R.string.user_credentials);
     }

     protected void announceRemoval(String alias) {
         if (!isAdded()) {
             return;
         }
         getListView().announceForAccessibility(getString(R.string.user_credential_removed, alias));
     }

     protected void refreshItems() {
         if (isAdded()) {
             new AliasLoader().execute();
         }
     }

     public static class CredentialDialogFragment extends InstrumentedDialogFragment {
         private static final String TAG = "CredentialDialogFragment";
         private static final String ARG_CREDENTIAL = "credential";

         public static void show(Fragment target, Credential item) {
             final Bundle args = new Bundle();
             args.putParcelable(ARG_CREDENTIAL, item);

             if (target.getFragmentManager().findFragmentByTag(TAG) == null) {
                 final DialogFragment frag = new CredentialDialogFragment();
                 frag.setTargetFragment(target, /* requestCode */ -1);
                 frag.setArguments(args);
                 frag.show(target.getFragmentManager(), TAG);
             }
         }

         @Override
         public Dialog onCreateDialog(Bundle savedInstanceState) {
             final Credential item = (Credential) getArguments().getParcelable(ARG_CREDENTIAL);

             View root = getActivity().getLayoutInflater()
                     .inflate(R.layout.user_credential_dialog, null);
             ViewGroup infoContainer = (ViewGroup) root.findViewById(R.id.credential_container);
             View contentView = getCredentialView(item, R.layout.user_credential, null,
                     infoContainer, /* expanded */ true);
             infoContainer.addView(contentView);

             AlertDialog.Builder builder = new AlertDialog.Builder(getActivity())
                     .setView(root)
                     .setTitle(R.string.user_credential_title)
                     .setPositiveButton(R.string.done, null);

             final String restriction = UserManager.DISALLOW_CONFIG_CREDENTIALS;
             final int myUserId = UserHandle.myUserId();
             if (!RestrictedLockUtils.hasBaseUserRestriction(getContext(), restriction, myUserId)) {
                 DialogInterface.OnClickListener listener = new DialogInterface.OnClickListener() {
                     @Override public void onClick(DialogInterface dialog, int id) {
                         final EnforcedAdmin admin = RestrictedLockUtils.checkIfRestrictionEnforced(
                                 getContext(), restriction, myUserId);
                         if (admin != null) {
                             RestrictedLockUtils.sendShowAdminSupportDetailsIntent(getContext(),
                                     admin);
                         } else {
                             new RemoveCredentialsTask(getContext(), getTargetFragment())
                                     .execute(item);
                         }
                         dialog.dismiss();
                     }
                 };
                 if (item.isSystem()) {
                     // TODO: a safe means of clearing wifi certificates. Configs refer to aliases
                     //       directly so deleting certs will break dependent access points.
                     builder.setNegativeButton(R.string.trusted_credentials_remove_label, listener);
                 }
             }
             return builder.create();
         }

         @Override
         public int getMetricsCategory() {
             return MetricsEvent.DIALOG_USER_CREDENTIAL;
         }

         /**
          * Deletes all certificates and keys under a given alias.
          *
          * If the {@link Credential} is for a system alias, all active grants to the alias will be
          * removed using {@link KeyChain}.
          */
         private class RemoveCredentialsTask extends AsyncTask<Credential, Void, Credential[]> {
             private Context context;
             private Fragment targetFragment;

             public RemoveCredentialsTask(Context context, Fragment targetFragment) {
                 this.context = context;
                 this.targetFragment = targetFragment;
             }

             @Override
             protected Credential[] doInBackground(Credential... credentials) {
                 for (final Credential credential : credentials) {
                     if (credential.isSystem()) {
                         removeGrantsAndDelete(credential);
                         continue;
                     }
                     throw new UnsupportedOperationException(
                             "Not implemented for wifi certificates. This should not be reachable.");
                 }
                 return credentials;
             }

             private void removeGrantsAndDelete(final Credential credential) {
                 final KeyChainConnection conn;
                 try {
                     conn = KeyChain.bind(getContext());
                 } catch (InterruptedException e) {
                     Log.w(TAG, "Connecting to KeyChain", e);
                     return;
                 }

                 try {
                     IKeyChainService keyChain = conn.getService();
                     keyChain.removeKeyPair(credential.alias);
                 } catch (RemoteException e) {
                     Log.w(TAG, "Removing credentials", e);
                 } finally {
                     conn.close();
                 }
             }

             @Override
             protected void onPostExecute(Credential... credentials) {
                 if (targetFragment instanceof UserCredentialsSettings && targetFragment.isAdded()) {
                     final UserCredentialsSettings target = (UserCredentialsSettings) targetFragment;
                     for (final Credential credential : credentials) {
                         target.announceRemoval(credential.alias);
                     }
                     target.refreshItems();
                 }
             }
         }
     }

     /**
      * Opens a background connection to KeyStore to list user credentials.
      * The credentials are stored in a {@link CredentialAdapter} attached to the main
      * {@link ListView} in the fragment.
      */
     private class AliasLoader extends AsyncTask<Void, Void, List<Credential>> {
         /**
          * @return a list of credentials ordered:
          * <ol>
          *   <li>first by purpose;</li>
          *   <li>then by alias.</li>
          * </ol>
          */
         @Override
         protected List<Credential> doInBackground(Void... params) {
             final KeyStore keyStore = KeyStore.getInstance();

             // Certificates can be installed into SYSTEM_UID or WIFI_UID through CertInstaller.
             final int myUserId = UserHandle.myUserId();
             final int systemUid = UserHandle.getUid(myUserId, Process.SYSTEM_UID);
             final int wifiUid = UserHandle.getUid(myUserId, Process.WIFI_UID);

             List<Credential> credentials = new ArrayList<>();
             credentials.addAll(getCredentialsForUid(keyStore, systemUid).values());
             credentials.addAll(getCredentialsForUid(keyStore, wifiUid).values());
             return credentials;
         }

         private boolean isAsymmetric(KeyStore keyStore, String alias, int uid)
             throws UnrecoverableKeyException {
                 KeyCharacteristics keyCharacteristics = new KeyCharacteristics();
                 int errorCode = keyStore.getKeyCharacteristics(alias, null, null, uid,
                         keyCharacteristics);
                 if (errorCode != KeyStore.NO_ERROR) {
                     throw (UnrecoverableKeyException)
                             new UnrecoverableKeyException("Failed to obtain information about key")
                                     .initCause(KeyStore.getKeyStoreException(errorCode));
                 }
                 Integer keymasterAlgorithm = keyCharacteristics.getEnum(
                         KeymasterDefs.KM_TAG_ALGORITHM);
                 if (keymasterAlgorithm == null) {
                     throw new UnrecoverableKeyException("Key algorithm unknown");
                 }
                 return keymasterAlgorithm == KeymasterDefs.KM_ALGORITHM_RSA ||
                         keymasterAlgorithm == KeymasterDefs.KM_ALGORITHM_EC;
         }

         private SortedMap<String, Credential> getCredentialsForUid(KeyStore keyStore, int uid) {
             final SortedMap<String, Credential> aliasMap = new TreeMap<>();
             for (final Credential.Type type : Credential.Type.values()) {
                 for (final String prefix : type.prefix) {
                     for (final String alias : keyStore.list(prefix, uid)) {
                         if (UserHandle.getAppId(uid) == Process.SYSTEM_UID) {
                             // Do not show work profile keys in user credentials
                             if (alias.startsWith(LockPatternUtils.PROFILE_KEY_NAME_ENCRYPT) ||
                                     alias.startsWith(LockPatternUtils.PROFILE_KEY_NAME_DECRYPT)) {
                                 continue;
                             }
                             // Do not show synthetic password keys in user credential
                             if (alias.startsWith(LockPatternUtils.SYNTHETIC_PASSWORD_KEY_PREFIX)) {
                                 continue;
                             }
                         }
                         try {
                             if (type == Credential.Type.USER_KEY &&
                                     !isAsymmetric(keyStore, prefix + alias, uid)) {
                                 continue;
                             }
                         } catch (UnrecoverableKeyException e) {
                             Log.e(TAG, "Unable to determine algorithm of key: " + prefix + alias, e);
                             continue;
                         }
                         Credential c = aliasMap.get(alias);
                         if (c == null) {
                             c = new Credential(alias, uid);
                             aliasMap.put(alias, c);
                         }
                         c.storedTypes.add(type);
                     }
                 }
             }
             return aliasMap;
         }

         @Override
         protected void onPostExecute(List<Credential> credentials) {
             if (!isAdded()) {
                 return;
             }

             if (credentials == null || credentials.size() == 0) {
                 // Create a "no credentials installed" message for the empty case.
                 TextView emptyTextView = (TextView) getActivity().findViewById(android.R.id.empty);
                 emptyTextView.setText(R.string.user_credential_none_installed);
                 setEmptyView(emptyTextView);
             } else {
                 setEmptyView(null);
             }

             getListView().setAdapter(
                     new CredentialAdapter(credentials, UserCredentialsSettings.this));
         }
     }

     /**
      * Helper class to display {@link Credential}s in a list.
      */
     private static class CredentialAdapter extends RecyclerView.Adapter<ViewHolder> {
         private static final int LAYOUT_RESOURCE = R.layout.user_credential_preference;

         private final List<Credential> mItems;
         private final View.OnClickListener mListener;

         public CredentialAdapter(List<Credential> items, @Nullable View.OnClickListener listener) {
             mItems = items;
             mListener = listener;
         }

         @Override
         public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
             final LayoutInflater inflater = LayoutInflater.from(parent.getContext());
             return new ViewHolder(inflater.inflate(LAYOUT_RESOURCE, parent, false));
         }

         @Override
         public void onBindViewHolder(ViewHolder h, int position) {
             getCredentialView(mItems.get(position), LAYOUT_RESOURCE, h.itemView, null, false);
             h.itemView.setTag(mItems.get(position));
             h.itemView.setOnClickListener(mListener);
         }

         @Override
         public int getItemCount() {
             return mItems.size();
         }
     }

     private static class ViewHolder extends RecyclerView.ViewHolder {
         public ViewHolder(View item) {
             super(item);
         }
     }

     /**
      * Mapping from View IDs in {@link R} to the types of credentials they describe.
      */
     private static final SparseArray<Credential.Type> credentialViewTypes = new SparseArray<>();
     static {
         credentialViewTypes.put(R.id.contents_userkey, Credential.Type.USER_KEY);
         credentialViewTypes.put(R.id.contents_usercrt, Credential.Type.USER_CERTIFICATE);
         credentialViewTypes.put(R.id.contents_cacrt, Credential.Type.CA_CERTIFICATE);
     }

     protected static View getCredentialView(Credential item, @LayoutRes int layoutResource,
             @Nullable View view, ViewGroup parent, boolean expanded) {
         if (view == null) {
             view = LayoutInflater.from(parent.getContext()).inflate(layoutResource, parent, false);
         }

         ((TextView) view.findViewById(R.id.alias)).setText(item.alias);
         ((TextView) view.findViewById(R.id.purpose)).setText(item.isSystem()
                 ? R.string.credential_for_vpn_and_apps
                 : R.string.credential_for_wifi);

         view.findViewById(R.id.contents).setVisibility(expanded ? View.VISIBLE : View.GONE);
         if (expanded) {
             for (int i = 0; i < credentialViewTypes.size(); i++) {
                 final View detail = view.findViewById(credentialViewTypes.keyAt(i));
                 detail.setVisibility(item.storedTypes.contains(credentialViewTypes.valueAt(i))
                         ? View.VISIBLE : View.GONE);
             }
         }
         return view;
     }

     static class AliasEntry {
         public String alias;
         public int uid;
     }

     static class Credential implements Parcelable {
         static enum Type {
             CA_CERTIFICATE (Credentials.CA_CERTIFICATE),
             USER_CERTIFICATE (Credentials.USER_CERTIFICATE),
             USER_KEY(Credentials.USER_PRIVATE_KEY, Credentials.USER_SECRET_KEY);

             final String[] prefix;

             Type(String... prefix) {
                 this.prefix = prefix;
             }
         }

         /**
          * Main part of the credential's alias. To fetch an item from KeyStore, prepend one of the
          * prefixes from {@link CredentialItem.storedTypes}.
          */
         final String alias;

         /**
          * UID under which this credential is stored. Typically {@link Process#SYSTEM_UID} but can
          * also be {@link Process#WIFI_UID} for credentials installed as wifi certificates.
          */
         final int uid;

         /**
          * Should contain some non-empty subset of:
          * <ul>
          *   <li>{@link Credentials.CA_CERTIFICATE}</li>
          *   <li>{@link Credentials.USER_CERTIFICATE}</li>
          *   <li>{@link Credentials.USER_KEY}</li>
          * </ul>
          */
         final EnumSet<Type> storedTypes = EnumSet.noneOf(Type.class);

         Credential(final String alias, final int uid) {
             this.alias = alias;
             this.uid = uid;
         }

         Credential(Parcel in) {
             this(in.readString(), in.readInt());

             long typeBits = in.readLong();
             for (Type i : Type.values()) {
                 if ((typeBits & (1L << i.ordinal())) != 0L) {
                     storedTypes.add(i);
                 }
             }
         }

         public void writeToParcel(Parcel out, int flags) {
             out.writeString(alias);
             out.writeInt(uid);

             long typeBits = 0;
             for (Type i : storedTypes) {
                 typeBits |= 1L << i.ordinal();
             }
             out.writeLong(typeBits);
         }

         public int describeContents() {
             return 0;
         }

         public static final Parcelable.Creator<Credential> CREATOR
                 = new Parcelable.Creator<Credential>() {
             public Credential createFromParcel(Parcel in) {
                 return new Credential(in);
             }

             public Credential[] newArray(int size) {
                 return new Credential[size];
             }
         };

         public boolean isSystem() {
             return UserHandle.getAppId(uid) == Process.SYSTEM_UID;
         }
     }
 }
	/*
	* Copyright (C) 2015 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;

	import android.annotation.LayoutRes;
	import android.annotation.Nullable;
	import android.app.Dialog;
	import android.content.Context;
	import android.content.DialogInterface;
	import android.os.AsyncTask;
	import android.os.Bundle;
	import android.os.Parcel;
	import android.os.Parcelable;
	import android.os.Process;
	import android.os.RemoteException;
	import android.os.UserHandle;
	import android.os.UserManager;
	import android.security.Credentials;
	import android.security.IKeyChainService;
	import android.security.KeyChain;
	import android.security.KeyChain.KeyChainConnection;
	import android.security.KeyStore;
	import android.security.keymaster.KeyCharacteristics;
	import android.security.keymaster.KeymasterDefs;
	import android.util.Log;
	import android.util.SparseArray;
	import android.view.LayoutInflater;
	import android.view.View;
	import android.view.ViewGroup;
	import android.widget.TextView;

	import com.android.internal.logging.nano.MetricsProto.MetricsEvent;
	import com.android.internal.widget.LockPatternUtils;
	import com.android.settings.core.instrumentation.InstrumentedDialogFragment;
	import com.android.settingslib.RestrictedLockUtils;
	import com.android.settingslib.RestrictedLockUtils.EnforcedAdmin;

	import java.security.UnrecoverableKeyException;
	import java.util.ArrayList;
	import java.util.EnumSet;
	import java.util.List;
	import java.util.SortedMap;
	import java.util.TreeMap;

	import androidx.appcompat.app.AlertDialog;
	import androidx.fragment.app.DialogFragment;
	import androidx.fragment.app.Fragment;
	import androidx.recyclerview.widget.RecyclerView;

	public class UserCredentialsSettings extends SettingsPreferenceFragment
	implements View.OnClickListener {
	private static final String TAG = "UserCredentialsSettings";

	@Override
	public int getMetricsCategory() {
	return MetricsEvent.USER_CREDENTIALS;
	}

	@Override
	public void onResume() {
	super.onResume();
	refreshItems();
	}

	@Override
	public void onClick(final View view) {
	final Credential item = (Credential) view.getTag();
	if (item != null) {
	CredentialDialogFragment.show(this, item);
	}
	}

	@Override
	public void onCreate(@Nullable Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	getActivity().setTitle(R.string.user_credentials);
	}

	protected void announceRemoval(String alias) {
	if (!isAdded()) {
	return;
	}
	getListView().announceForAccessibility(getString(R.string.user_credential_removed, alias));
	}

	protected void refreshItems() {
	if (isAdded()) {
	new AliasLoader().execute();
	}
	}

	public static class CredentialDialogFragment extends InstrumentedDialogFragment {
	private static final String TAG = "CredentialDialogFragment";
	private static final String ARG_CREDENTIAL = "credential";

	public static void show(Fragment target, Credential item) {
	final Bundle args = new Bundle();
	args.putParcelable(ARG_CREDENTIAL, item);

	if (target.getFragmentManager().findFragmentByTag(TAG) == null) {
	final DialogFragment frag = new CredentialDialogFragment();
	frag.setTargetFragment(target, /* requestCode */ -1);
	frag.setArguments(args);
	frag.show(target.getFragmentManager(), TAG);
	}
	}

	@Override
	public Dialog onCreateDialog(Bundle savedInstanceState) {
	final Credential item = (Credential) getArguments().getParcelable(ARG_CREDENTIAL);

	View root = getActivity().getLayoutInflater()
	.inflate(R.layout.user_credential_dialog, null);
	ViewGroup infoContainer = (ViewGroup) root.findViewById(R.id.credential_container);
	View contentView = getCredentialView(item, R.layout.user_credential, null,
	infoContainer, /* expanded */ true);
	infoContainer.addView(contentView);

	AlertDialog.Builder builder = new AlertDialog.Builder(getActivity())
	.setView(root)
	.setTitle(R.string.user_credential_title)
	.setPositiveButton(R.string.done, null);

	final String restriction = UserManager.DISALLOW_CONFIG_CREDENTIALS;
	final int myUserId = UserHandle.myUserId();
	if (!RestrictedLockUtils.hasBaseUserRestriction(getContext(), restriction, myUserId)) {
	DialogInterface.OnClickListener listener = new DialogInterface.OnClickListener() {
	@Override public void onClick(DialogInterface dialog, int id) {
	final EnforcedAdmin admin = RestrictedLockUtils.checkIfRestrictionEnforced(
	getContext(), restriction, myUserId);
	if (admin != null) {
	RestrictedLockUtils.sendShowAdminSupportDetailsIntent(getContext(),
	admin);
	} else {
	new RemoveCredentialsTask(getContext(), getTargetFragment())
	.execute(item);
	}
	dialog.dismiss();
	}
	};
	if (item.isSystem()) {
	// TODO: a safe means of clearing wifi certificates. Configs refer to aliases
	// directly so deleting certs will break dependent access points.
	builder.setNegativeButton(R.string.trusted_credentials_remove_label, listener);
	}
	}
	return builder.create();
	}

	@Override
	public int getMetricsCategory() {
	return MetricsEvent.DIALOG_USER_CREDENTIAL;
	}

	/**
	* Deletes all certificates and keys under a given alias.
	*
	* If the {@link Credential} is for a system alias, all active grants to the alias will be
	* removed using {@link KeyChain}.
	*/
	private class RemoveCredentialsTask extends AsyncTask<Credential, Void, Credential[]> {
	private Context context;
	private Fragment targetFragment;

	public RemoveCredentialsTask(Context context, Fragment targetFragment) {
	this.context = context;
	this.targetFragment = targetFragment;
	}

	@Override
	protected Credential[] doInBackground(Credential... credentials) {
	for (final Credential credential : credentials) {
	if (credential.isSystem()) {
	removeGrantsAndDelete(credential);
	continue;
	}
	throw new UnsupportedOperationException(
	"Not implemented for wifi certificates. This should not be reachable.");
	}
	return credentials;
	}

	private void removeGrantsAndDelete(final Credential credential) {
	final KeyChainConnection conn;
	try {
	conn = KeyChain.bind(getContext());
	} catch (InterruptedException e) {
	Log.w(TAG, "Connecting to KeyChain", e);
	return;
	}

	try {
	IKeyChainService keyChain = conn.getService();
	keyChain.removeKeyPair(credential.alias);
	} catch (RemoteException e) {
	Log.w(TAG, "Removing credentials", e);
	} finally {
	conn.close();
	}
	}

	@Override
	protected void onPostExecute(Credential... credentials) {
	if (targetFragment instanceof UserCredentialsSettings && targetFragment.isAdded()) {
	final UserCredentialsSettings target = (UserCredentialsSettings) targetFragment;
	for (final Credential credential : credentials) {
	target.announceRemoval(credential.alias);
	}
	target.refreshItems();
	}
	}
	}
	}

	/**
	* Opens a background connection to KeyStore to list user credentials.
	* The credentials are stored in a {@link CredentialAdapter} attached to the main
	* {@link ListView} in the fragment.
	*/
	private class AliasLoader extends AsyncTask<Void, Void, List<Credential>> {
	/**
	* @return a list of credentials ordered:
	* <ol>
	* <li>first by purpose;</li>
	* <li>then by alias.</li>
	* </ol>
	*/
	@Override
	protected List<Credential> doInBackground(Void... params) {
	final KeyStore keyStore = KeyStore.getInstance();

	// Certificates can be installed into SYSTEM_UID or WIFI_UID through CertInstaller.
	final int myUserId = UserHandle.myUserId();
	final int systemUid = UserHandle.getUid(myUserId, Process.SYSTEM_UID);
	final int wifiUid = UserHandle.getUid(myUserId, Process.WIFI_UID);

	List<Credential> credentials = new ArrayList<>();
	credentials.addAll(getCredentialsForUid(keyStore, systemUid).values());
	credentials.addAll(getCredentialsForUid(keyStore, wifiUid).values());
	return credentials;
	}

	private boolean isAsymmetric(KeyStore keyStore, String alias, int uid)
	throws UnrecoverableKeyException {
	KeyCharacteristics keyCharacteristics = new KeyCharacteristics();
	int errorCode = keyStore.getKeyCharacteristics(alias, null, null, uid,
	keyCharacteristics);
	if (errorCode != KeyStore.NO_ERROR) {
	throw (UnrecoverableKeyException)
	new UnrecoverableKeyException("Failed to obtain information about key")
	.initCause(KeyStore.getKeyStoreException(errorCode));
	}
	Integer keymasterAlgorithm = keyCharacteristics.getEnum(
	KeymasterDefs.KM_TAG_ALGORITHM);
	if (keymasterAlgorithm == null) {
	throw new UnrecoverableKeyException("Key algorithm unknown");
	}
	return keymasterAlgorithm == KeymasterDefs.KM_ALGORITHM_RSA \|\|
	keymasterAlgorithm == KeymasterDefs.KM_ALGORITHM_EC;
	}

	private SortedMap<String, Credential> getCredentialsForUid(KeyStore keyStore, int uid) {
	final SortedMap<String, Credential> aliasMap = new TreeMap<>();
	for (final Credential.Type type : Credential.Type.values()) {
	for (final String prefix : type.prefix) {
	for (final String alias : keyStore.list(prefix, uid)) {
	if (UserHandle.getAppId(uid) == Process.SYSTEM_UID) {
	// Do not show work profile keys in user credentials
	if (alias.startsWith(LockPatternUtils.PROFILE_KEY_NAME_ENCRYPT) \|\|
	alias.startsWith(LockPatternUtils.PROFILE_KEY_NAME_DECRYPT)) {
	continue;
	}
	// Do not show synthetic password keys in user credential
	if (alias.startsWith(LockPatternUtils.SYNTHETIC_PASSWORD_KEY_PREFIX)) {
	continue;
	}
	}
	try {
	if (type == Credential.Type.USER_KEY &&
	!isAsymmetric(keyStore, prefix + alias, uid)) {
	continue;
	}
	} catch (UnrecoverableKeyException e) {
	Log.e(TAG, "Unable to determine algorithm of key: " + prefix + alias, e);
	continue;
	}
	Credential c = aliasMap.get(alias);
	if (c == null) {
	c = new Credential(alias, uid);
	aliasMap.put(alias, c);
	}
	c.storedTypes.add(type);
	}
	}
	}
	return aliasMap;
	}

	@Override
	protected void onPostExecute(List<Credential> credentials) {
	if (!isAdded()) {
	return;
	}

	if (credentials == null \|\| credentials.size() == 0) {
	// Create a "no credentials installed" message for the empty case.
	TextView emptyTextView = (TextView) getActivity().findViewById(android.R.id.empty);
	emptyTextView.setText(R.string.user_credential_none_installed);
	setEmptyView(emptyTextView);
	} else {
	setEmptyView(null);
	}

	getListView().setAdapter(
	new CredentialAdapter(credentials, UserCredentialsSettings.this));
	}
	}

	/**
	* Helper class to display {@link Credential}s in a list.
	*/
	private static class CredentialAdapter extends RecyclerView.Adapter<ViewHolder> {
	private static final int LAYOUT_RESOURCE = R.layout.user_credential_preference;

	private final List<Credential> mItems;
	private final View.OnClickListener mListener;

	public CredentialAdapter(List<Credential> items, @Nullable View.OnClickListener listener) {
	mItems = items;
	mListener = listener;
	}

	@Override
	public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
	final LayoutInflater inflater = LayoutInflater.from(parent.getContext());
	return new ViewHolder(inflater.inflate(LAYOUT_RESOURCE, parent, false));
	}

	@Override
	public void onBindViewHolder(ViewHolder h, int position) {
	getCredentialView(mItems.get(position), LAYOUT_RESOURCE, h.itemView, null, false);
	h.itemView.setTag(mItems.get(position));
	h.itemView.setOnClickListener(mListener);
	}

	@Override
	public int getItemCount() {
	return mItems.size();
	}
	}

	private static class ViewHolder extends RecyclerView.ViewHolder {
	public ViewHolder(View item) {
	super(item);
	}
	}

	/**
	* Mapping from View IDs in {@link R} to the types of credentials they describe.
	*/
	private static final SparseArray<Credential.Type> credentialViewTypes = new SparseArray<>();
	static {
	credentialViewTypes.put(R.id.contents_userkey, Credential.Type.USER_KEY);
	credentialViewTypes.put(R.id.contents_usercrt, Credential.Type.USER_CERTIFICATE);
	credentialViewTypes.put(R.id.contents_cacrt, Credential.Type.CA_CERTIFICATE);
	}

	protected static View getCredentialView(Credential item, @LayoutRes int layoutResource,
	@Nullable View view, ViewGroup parent, boolean expanded) {
	if (view == null) {
	view = LayoutInflater.from(parent.getContext()).inflate(layoutResource, parent, false);
	}

	((TextView) view.findViewById(R.id.alias)).setText(item.alias);
	((TextView) view.findViewById(R.id.purpose)).setText(item.isSystem()
	? R.string.credential_for_vpn_and_apps
	: R.string.credential_for_wifi);

	view.findViewById(R.id.contents).setVisibility(expanded ? View.VISIBLE : View.GONE);
	if (expanded) {
	for (int i = 0; i < credentialViewTypes.size(); i++) {
	final View detail = view.findViewById(credentialViewTypes.keyAt(i));
	detail.setVisibility(item.storedTypes.contains(credentialViewTypes.valueAt(i))
	? View.VISIBLE : View.GONE);
	}
	}
	return view;
	}

	static class AliasEntry {
	public String alias;
	public int uid;
	}

	static class Credential implements Parcelable {
	static enum Type {
	CA_CERTIFICATE (Credentials.CA_CERTIFICATE),
	USER_CERTIFICATE (Credentials.USER_CERTIFICATE),
	USER_KEY(Credentials.USER_PRIVATE_KEY, Credentials.USER_SECRET_KEY);

	final String[] prefix;

	Type(String... prefix) {
	this.prefix = prefix;
	}
	}

	/**
	* Main part of the credential's alias. To fetch an item from KeyStore, prepend one of the
	* prefixes from {@link CredentialItem.storedTypes}.
	*/
	final String alias;

	/**
	* UID under which this credential is stored. Typically {@link Process#SYSTEM_UID} but can
	* also be {@link Process#WIFI_UID} for credentials installed as wifi certificates.
	*/
	final int uid;

	/**
	* Should contain some non-empty subset of:
	* <ul>
	* <li>{@link Credentials.CA_CERTIFICATE}</li>
	* <li>{@link Credentials.USER_CERTIFICATE}</li>
	* <li>{@link Credentials.USER_KEY}</li>
	* </ul>
	*/
	final EnumSet<Type> storedTypes = EnumSet.noneOf(Type.class);

	Credential(final String alias, final int uid) {
	this.alias = alias;
	this.uid = uid;
	}

	Credential(Parcel in) {
	this(in.readString(), in.readInt());

	long typeBits = in.readLong();
	for (Type i : Type.values()) {
	if ((typeBits & (1L << i.ordinal())) != 0L) {
	storedTypes.add(i);
	}
	}
	}

	public void writeToParcel(Parcel out, int flags) {
	out.writeString(alias);
	out.writeInt(uid);

	long typeBits = 0;
	for (Type i : storedTypes) {
	typeBits \|= 1L << i.ordinal();
	}
	out.writeLong(typeBits);
	}

	public int describeContents() {
	return 0;
	}

	public static final Parcelable.Creator<Credential> CREATOR
	= new Parcelable.Creator<Credential>() {
	public Credential createFromParcel(Parcel in) {
	return new Credential(in);
	}

	public Credential[] newArray(int size) {
	return new Credential[size];
	}
	};

	public boolean isSystem() {
	return UserHandle.getAppId(uid) == Process.SYSTEM_UID;
	}
	}
	}