42f6528b98
The KeyChain API is Currently in use by Browser and validated by Email for client certificate authentication. Change-Id: Ifeab416be594457a05747406e31656e71795cb53
416 lines
17 KiB
Java
416 lines
17 KiB
Java
/*
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* Copyright (C) 2011 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package android.security;
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import android.accounts.Account;
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import android.accounts.AccountManager;
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import android.accounts.AccountManagerCallback;
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import android.accounts.AccountManagerFuture;
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import android.accounts.AuthenticatorException;
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import android.accounts.OperationCanceledException;
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import android.app.Activity;
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import android.content.ComponentName;
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import android.content.Context;
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import android.content.Intent;
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import android.content.ServiceConnection;
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import android.os.Bundle;
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import android.os.IBinder;
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import android.os.Looper;
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import android.os.RemoteException;
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import java.io.ByteArrayInputStream;
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import java.io.Closeable;
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import java.io.IOException;
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import java.security.KeyFactory;
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import java.security.KeyPair;
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import java.security.NoSuchAlgorithmException;
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import java.security.Principal;
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import java.security.PrivateKey;
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import java.security.cert.Certificate;
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import java.security.cert.CertificateException;
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import java.security.cert.CertificateFactory;
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import java.security.cert.X509Certificate;
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import java.security.spec.InvalidKeySpecException;
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import java.security.spec.PKCS8EncodedKeySpec;
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import java.util.concurrent.BlockingQueue;
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import java.util.concurrent.LinkedBlockingQueue;
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/**
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* The {@code KeyChain} class provides access to private keys and
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* their corresponding certificate chains in credential storage.
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*
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* <p>Applications accessing the {@code KeyChain} normally go through
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* these steps:
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*
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* <ol>
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*
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* <li>Receive a callback from an {@link javax.net.ssl.X509KeyManager
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* X509KeyManager} that a private key is requested.
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*
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* <li>Call {@link #choosePrivateKeyAlias
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* choosePrivateKeyAlias} to allow the user to select from a
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* list of currently available private keys and corresponding
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* certificate chains. The chosen alias will be returned by the
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* callback {@link KeyChainAliasCallback#alias}, or null if no private
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* key is available or the user cancels the request.
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*
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* <li>Call {@link #getPrivateKey} and {@link #getCertificateChain} to
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* retrieve the credentials to return to the corresponding {@link
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* javax.net.ssl.X509KeyManager} callbacks.
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*
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* </ol>
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*
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* <p>An application may remember the value of a selected alias to
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* avoid prompting the user with {@link #choosePrivateKeyAlias
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* choosePrivateKeyAlias} on subsequent connections. If the alias is
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* no longer valid, null will be returned on lookups using that value
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*/
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// TODO reference intent for credential installation when public
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public final class KeyChain {
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private static final String TAG = "KeyChain";
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/**
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* @hide Also used by KeyChainService implementation
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*/
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public static final String ACCOUNT_TYPE = "com.android.keychain";
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/**
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* @hide Also used by KeyChainActivity implementation
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*/
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public static final String EXTRA_RESPONSE = "response";
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/**
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* Launches an {@code Activity} for the user to select the alias
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* for a private key and certificate pair for authentication. The
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* selected alias or null will be returned via the
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* KeyChainAliasCallback callback.
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*
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* <p>{@code keyTypes} and {@code issuers} may be used to
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* highlight suggested choices to the user, although to cope with
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* sometimes erroneous values provided by servers, the user may be
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* able to override these suggestions.
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*
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* <p>{@code host} and {@code port} may be used to give the user
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* more context about the server requesting the credentials.
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*
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* <p>This method requires the caller to hold the permission
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* {@link android.Manifest.permission#USE_CREDENTIALS}.
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*
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* @param activity The {@link Activity} context to use for
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* launching the new sub-Activity to prompt the user to select
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* a private key; used only to call startActivity(); must not
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* be null.
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* @param response Callback to invoke when the request completes;
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* must not be null
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* @param keyTypes The acceptable types of asymmetric keys such as
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* "RSA" or "DSA", or a null array.
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* @param issuers The acceptable certificate issuers for the
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* certificate matching the private key, or null.
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* @param host The host name of the server requesting the
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* certificate, or null if unavailable.
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* @param port The port number of the server requesting the
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* certificate, or -1 if unavailable.
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*/
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public static void choosePrivateKeyAlias(Activity activity, KeyChainAliasCallback response,
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String[] keyTypes, Principal[] issuers,
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String host, int port) {
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/*
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* TODO currently keyTypes, issuers, host, and port are
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* unused. They are meant to follow the semantics and purpose
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* of X509KeyManager method arguments.
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*
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* keyTypes would allow the list to be filtered and typically
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* will be set correctly by the server. In practice today,
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* most all users will want only RSA, rarely DSA, and usually
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* only a small number of certs will be available.
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*
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* issuers is typically not useful. Some servers historically
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* will send the entire list of public CAs known to the
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* server. Others will send none. If this is used, if there
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* are no matches after applying the constraint, it should be
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* ignored.
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*
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* host and port may be shown to the user if available, but it
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* should be clear that they are not validated values, perhaps
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* shown along with requesting application identity to clarify
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* the source of the request.
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*/
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if (activity == null) {
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throw new NullPointerException("activity == null");
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}
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if (response == null) {
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throw new NullPointerException("response == null");
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}
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Intent intent = new Intent("com.android.keychain.CHOOSER");
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intent.putExtra(EXTRA_RESPONSE, new AliasResponse(activity, response));
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activity.startActivity(intent);
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}
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private static class AliasResponse extends IKeyChainAliasCallback.Stub {
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private final Activity activity;
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private final KeyChainAliasCallback keyChainAliasResponse;
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private AliasResponse(Activity activity, KeyChainAliasCallback keyChainAliasResponse) {
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this.activity = activity;
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this.keyChainAliasResponse = keyChainAliasResponse;
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}
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@Override public void alias(String alias) {
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if (alias == null) {
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keyChainAliasResponse.alias(null);
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return;
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}
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AccountManager accountManager = AccountManager.get(activity);
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accountManager.getAuthToken(getAccount(activity),
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alias,
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null,
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activity,
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new AliasAccountManagerCallback(keyChainAliasResponse,
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alias),
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null);
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}
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}
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private static class AliasAccountManagerCallback implements AccountManagerCallback<Bundle> {
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private final KeyChainAliasCallback keyChainAliasResponse;
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private final String alias;
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private AliasAccountManagerCallback(KeyChainAliasCallback keyChainAliasResponse,
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String alias) {
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this.keyChainAliasResponse = keyChainAliasResponse;
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this.alias = alias;
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}
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@Override public void run(AccountManagerFuture<Bundle> future) {
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Bundle bundle;
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try {
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bundle = future.getResult();
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} catch (OperationCanceledException e) {
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keyChainAliasResponse.alias(null);
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return;
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} catch (IOException e) {
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keyChainAliasResponse.alias(null);
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return;
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} catch (AuthenticatorException e) {
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keyChainAliasResponse.alias(null);
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return;
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}
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String authToken = bundle.getString(AccountManager.KEY_AUTHTOKEN);
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if (authToken != null) {
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keyChainAliasResponse.alias(alias);
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} else {
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keyChainAliasResponse.alias(null);
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}
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}
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}
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/**
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* Returns the {@code PrivateKey} for the requested alias, or null
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* if no there is no result.
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*
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* <p>This method requires the caller to hold the permission
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* {@link android.Manifest.permission#USE_CREDENTIALS}.
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*
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* @param alias The alias of the desired private key, typically
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* returned via {@link KeyChainAliasCallback#alias}.
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* @throws KeyChainException if the alias was valid but there was some problem accessing it.
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*/
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public static PrivateKey getPrivateKey(Context context, String alias)
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throws KeyChainException, InterruptedException {
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if (alias == null) {
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throw new NullPointerException("alias == null");
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}
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KeyChainConnection keyChainConnection = bind(context);
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try {
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String authToken = authToken(context, alias);
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if (authToken == null) {
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return null;
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}
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IKeyChainService keyChainService = keyChainConnection.getService();
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byte[] privateKeyBytes = keyChainService.getPrivateKey(alias, authToken);
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return toPrivateKey(privateKeyBytes);
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} catch (RemoteException e) {
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throw new KeyChainException(e);
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} catch (RuntimeException e) {
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// only certain RuntimeExceptions can be propagated across the IKeyChainService call
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throw new KeyChainException(e);
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} finally {
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keyChainConnection.close();
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}
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}
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/**
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* Returns the {@code X509Certificate} chain for the requested
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* alias, or null if no there is no result.
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*
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* <p>This method requires the caller to hold the permission
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* {@link android.Manifest.permission#USE_CREDENTIALS}.
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*
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* @param alias The alias of the desired certificate chain, typically
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* returned via {@link KeyChainAliasCallback#alias}.
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* @throws KeyChainException if the alias was valid but there was some problem accessing it.
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*/
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public static X509Certificate[] getCertificateChain(Context context, String alias)
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throws KeyChainException, InterruptedException {
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if (alias == null) {
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throw new NullPointerException("alias == null");
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}
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KeyChainConnection keyChainConnection = bind(context);
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try {
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String authToken = authToken(context, alias);
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if (authToken == null) {
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return null;
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}
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IKeyChainService keyChainService = keyChainConnection.getService();
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byte[] certificateBytes = keyChainService.getCertificate(alias, authToken);
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return new X509Certificate[] { toCertificate(certificateBytes) };
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} catch (RemoteException e) {
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throw new KeyChainException(e);
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} catch (RuntimeException e) {
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// only certain RuntimeExceptions can be propagated across the IKeyChainService call
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throw new KeyChainException(e);
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} finally {
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keyChainConnection.close();
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}
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}
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private static PrivateKey toPrivateKey(byte[] bytes) {
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if (bytes == null) {
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throw new IllegalArgumentException("bytes == null");
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}
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try {
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KeyPair keyPair = (KeyPair) Credentials.convertFromPem(bytes).get(0);
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return keyPair.getPrivate();
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} catch (IOException e) {
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throw new AssertionError(e);
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}
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}
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private static X509Certificate toCertificate(byte[] bytes) {
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if (bytes == null) {
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throw new IllegalArgumentException("bytes == null");
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}
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try {
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CertificateFactory certFactory = CertificateFactory.getInstance("X.509");
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Certificate cert = certFactory.generateCertificate(new ByteArrayInputStream(bytes));
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return (X509Certificate) cert;
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} catch (CertificateException e) {
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throw new AssertionError(e);
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}
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}
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private static String authToken(Context context, String alias) {
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AccountManager accountManager = AccountManager.get(context);
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AccountManagerFuture<Bundle> future = accountManager.getAuthToken(getAccount(context),
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alias,
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false,
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null,
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null);
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Bundle bundle;
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try {
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bundle = future.getResult();
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} catch (OperationCanceledException e) {
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throw new AssertionError(e);
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} catch (IOException e) {
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// KeyChainAccountAuthenticator doesn't do I/O
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throw new AssertionError(e);
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} catch (AuthenticatorException e) {
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throw new AssertionError(e);
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}
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Intent intent = bundle.getParcelable(AccountManager.KEY_INTENT);
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if (intent != null) {
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return null;
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}
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String authToken = bundle.getString(AccountManager.KEY_AUTHTOKEN);
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if (authToken == null) {
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throw new AssertionError("Invalid authtoken");
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}
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return authToken;
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}
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private static Account getAccount(Context context) {
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AccountManager accountManager = AccountManager.get(context);
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Account[] accounts = accountManager.getAccountsByType(ACCOUNT_TYPE);
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if (accounts.length == 0) {
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try {
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// Account is created if necessary during binding of the IKeyChainService
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bind(context).close();
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} catch (InterruptedException e) {
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throw new AssertionError(e);
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}
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accounts = accountManager.getAccountsByType(ACCOUNT_TYPE);
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}
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return accounts[0];
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}
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/**
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* @hide for reuse by CertInstaller and Settings.
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* @see KeyChain#bind
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*/
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public final static class KeyChainConnection implements Closeable {
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private final Context context;
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private final ServiceConnection serviceConnection;
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private final IKeyChainService service;
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private KeyChainConnection(Context context,
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ServiceConnection serviceConnection,
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IKeyChainService service) {
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this.context = context;
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this.serviceConnection = serviceConnection;
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this.service = service;
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}
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@Override public void close() {
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context.unbindService(serviceConnection);
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}
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public IKeyChainService getService() {
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return service;
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}
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}
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/**
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* @hide for reuse by CertInstaller and Settings.
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*
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* Caller should call unbindService on the result when finished.
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*/
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public static KeyChainConnection bind(Context context) throws InterruptedException {
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if (context == null) {
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throw new NullPointerException("context == null");
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}
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ensureNotOnMainThread(context);
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final BlockingQueue<IKeyChainService> q = new LinkedBlockingQueue<IKeyChainService>(1);
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ServiceConnection keyChainServiceConnection = new ServiceConnection() {
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@Override public void onServiceConnected(ComponentName name, IBinder service) {
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try {
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q.put(IKeyChainService.Stub.asInterface(service));
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} catch (InterruptedException e) {
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throw new AssertionError(e);
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}
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}
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@Override public void onServiceDisconnected(ComponentName name) {}
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};
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boolean isBound = context.bindService(new Intent(IKeyChainService.class.getName()),
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keyChainServiceConnection,
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Context.BIND_AUTO_CREATE);
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if (!isBound) {
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throw new AssertionError("could not bind to KeyChainService");
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}
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return new KeyChainConnection(context, keyChainServiceConnection, q.take());
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}
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private static void ensureNotOnMainThread(Context context) {
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Looper looper = Looper.myLooper();
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if (looper != null && looper == context.getMainLooper()) {
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throw new IllegalStateException(
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"calling this from your main thread can lead to deadlock");
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}
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}
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}
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