安卓应用安全指南 4.1.1 创建/使用活动 示例代码

4.1.1 创建/使用活动 示例代码

原书：Android Application Secure Design/Secure Coding Guidebook 译者：飞龙 协议：CC BY-NC-SA 4.0

使用活动的风险和对策取决于活动的使用方式。 在本节中，我们根据活动的使用情况，对 4 种活动进行了分类。 你可以通过下面的图表来找出，你应该创建哪种类型的活动。 由于安全编程最佳实践根据活动的使用方式而有所不同，因此我们也将解释活动的实现。

表 4-1 活动类型的定义

类型	定义
私有	不能由其他应用加载，所以是最安全的活动
公共	应该由很多未指定的应用使用的活动
伙伴	只能由可信的伙伴公司开发的应用使用的活动
内部	只能由其他内部应用使用的活动

4.1.1.1 创建/使用私有活动

私有活动是其他应用程序无法启动的活动，因此它是最安全的活动。

当使用仅在应用程序中使用的活动（私有活动）时，只要你对类使用显示意图，那么你不必担心将它意外发送到任何其他应用程序。 但是，第三方应用程序可能会读取用于启动活动的意图。 因此，如果你将敏感信息放入用于启动活动的意图中，有必要采取对策，来确保它不会被恶意第三方读取。

下面展示了如何创建私有活动的示例代码。

要点（创建活动）：

1) 不要指定taskAffinity。

2) 不要指定launchMode。

3) 将导出属性明确设置为false。

4) 仔细和安全地处理收到的意图，即使意图从相同的应用发送。

5) 敏感信息可以发送，因为它发送和接收所有同一应用中的信息。

AndroidManifest.xml

代码语言：javascript复制

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="org.jssec.android.activity.privateactivity" >

    <application
        android:allowBackup="false"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >

        <!-- Private activity -->
        <!-- *** POINT 1 *** Do not specify taskAffinity -->
        <!-- *** POINT 2 *** Do not specify launchMode -->
        <!-- *** POINT 3 *** Explicitly set the exported attribute to false. -->
        <activity
            android:name=".PrivateActivity"
            android:label="@string/app_name"
            android:exported="false" />

        <!-- Public activity launched by launcher -->
        <activity
            android:name=".PrivateUserActivity"
            android:label="@string/app_name"
            android:exported="true" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>

PrivateActivity.java

代码语言：javascript复制

package org.jssec.android.activity.privateactivity;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

public class PrivateActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.private_activity);
        // *** POINT 4 *** Handle the received Intent carefully and securely, even though the Intent was sent from the same application.
        // Omitted, since this is a sample. Please refer to "3.2 Handling Input Data Carefully and Securely."
        String param = getIntent().getStringExtra("PARAM");
        Toast.makeText(this, String.format("Received param: ￥"%s￥"", param), Toast.LENGTH_LONG).show();
    }

    public void onReturnResultClick(View view) {
        // *** POINT 5 *** Sensitive information can be sent since it is sending and receiving all within the same application.
        Intent intent = new Intent();
        intent.putExtra("RESULT", "Sensitive Info");
        setResult(RESULT_OK, intent);
        finish();
    }
}

下面展示如何使用私有活动的示例代码。

要点（使用活动）；

6) 不要为意图设置FLAG_ACTIVITY_NEW_TASK标志来启动活动。

7) 使用显式意图，以及用于调用相同应用中的活动的特定的类。

8) 由于目标活动位于同一个应用中，因此只能通过putExtra()发送敏感信息 [1]。

警告：如果不遵守第 1, 2 和 6 点，第三方可能会读到意图。 更多详细信息，请参阅第 4.1.2.2 和 4.1.2.3 节。

9) 即使数据来自同一应用中的活动，也要小心并安全地处理收到的结果数据。

PrivateUserActivity.java

代码语言：javascript复制

package org.jssec.android.activity.privateactivity;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

public class PrivateUserActivity extends Activity {

    private static final int REQUEST_CODE = 1;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.user_activity);
    }

    public void onUseActivityClick(View view) {
        // *** POINT 6 *** Do not set the FLAG_ACTIVITY_NEW_TASK flag for intents to start an activity.
        // *** POINT 7 *** Use the explicit Intents with the class specified to call an activity in the same application.
        Intent intent = new Intent(this, PrivateActivity.class);
        // *** POINT 8 *** Sensitive information can be sent only by putExtra() since the destination activity is in the same application.
        intent.putExtra("PARAM", "Sensitive Info");
        startActivityForResult(intent, REQUEST_CODE);
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode != RESULT_OK) return;
        switch (requestCode) {
            case REQUEST_CODE:
                String result = data.getStringExtra("RESULT");
                // *** POINT 9 *** Handle the received data carefully and securely,
                // even though the data comes from an activity within the same application.
                // Omitted, since this is a sample. Please refer to "3.2 Handling Input Data Carefully and Securely."
                Toast.makeText(this, String.format("Received result: ￥"%s￥"", result), Toast.LENGTH_LONG).show();
                break;
        }
    }
}

4.1.1.2 创建/使用公共活动

公共活动是应该由大量未指定的应用程序使用的活动。 有必要注意的是，公共活动可能收到恶意软件发送的意图。 另外，使用公共活动时，有必要注意恶意软件也可以接收或阅读发送给他们的意图。

要点（创建活动）：

1) 将导出属性显式设置为true。

2) 小心并安全地处理接收到的意图。

3) 返回结果时，请勿包含敏感信息。

下面展示了创建公共活动的示例代码。

AndroidManifest.xml

代码语言：javascript复制

<?xml version="1.0" encoding="utf-8"?>
    <manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="org.jssec.android.activity.publicactivity" >

    <application
        android:allowBackup="false"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >

        <!-- Public Activity -->
        <!-- *** POINT 1 *** Explicitly set the exported attribute to true. -->
        <activity
            android:name=".PublicActivity"
            android:label="@string/app_name"
            android:exported="true">

            <!-- Define intent filter to receive an implicit intent for a specified action -->
            <intent-filter>
                <action android:name="org.jssec.android.activity.MY_ACTION" />
                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </activity>
    </application>
</manifest>

PublicActivity.java

代码语言：javascript复制

package org.jssec.android.activity.publicactivity;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

public class PublicActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        // *** POINT 2 *** Handle the received intent carefully and securely.
        // Since this is a public activity, it is possible that the sending application may be malware.
        // Omitted, since this is a sample. Please refer to "3.2 Handling Input Data Carefully and Securely."
        String param = getIntent().getStringExtra("PARAM");
        Toast.makeText(this, String.format("Received param: ¥"%s¥"", param), Toast.LENGTH_LONG).show();
    }

    public void onReturnResultClick(View view) {
        // *** POINT 3 *** When returning a result, do not include sensitive information.
        // Since this is a public activity, it is possible that the receiving application may be malware.
        // If there is no problem if the data gets received by malware, then it can be returned as a result.
        Intent intent = new Intent();
        intent.putExtra("RESULT", "Not Sensitive Info");
        setResult(RESULT_OK, intent);
        finish();
    }
}

接下来，这里是公共活动用户端的示例代码。

要点（使用活动）：

4) 不要发送敏感信息。

5) 收到结果时，请仔细并安全地处理数据。

PublicUserActivity.java

代码语言：javascript复制

package org.jssec.android.activity.publicuser;
import android.app.Activity;
import android.content.ActivityNotFoundException;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;
public class PublicUserActivity extends Activity {

    private static final int REQUEST_CODE = 1;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }

    public void onUseActivityClick(View view) {
        try {
            // *** POINT 4 *** Do not send sensitive information.
            Intent intent = new Intent("org.jssec.android.activity.MY_ACTION");
            intent.putExtra("PARAM", "Not Sensitive Info");
            startActivityForResult(intent, REQUEST_CODE);
        } catch (ActivityNotFoundException e) {
            Toast.makeText(this, "Target activity not found.", Toast.LENGTH_LONG).show();
        }
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        // *** POINT 5 *** When receiving a result, handle the data carefully and securely.
        // Omitted, since this is a sample. Please refer to "3.2 Handling Input Data Carefully and Securely."
        if (resultCode != RESULT_OK) return;
        switch (requestCode) {
            case REQUEST_CODE:
                String result = data.getStringExtra("RESULT");
                Toast.makeText(this, String.format("Received result: ¥"%s¥"", result), Toast.LENGTH_LONG).show();
                break;
        }
    }
}
```#### 4.1.1.3 创建/使用伙伴活动

伙伴活动是只能由特定应用程序使用的活动。 它们在想要安全共享信息和功能的伙伴公司之间使用。 

第三方应用程序可能会读取用于启动活动的意图。 因此，如果你将敏感信息放入用于启动活动的意图中，有必要采取对策来确保其无法被恶意第三方读取。

创建伙伴活动的示例代码如下所示。

要点（创建活动）：

1) 不要指定`taskAffinity`。

2) 不要指定`launchMode`。

3) 不要定义意图过滤器，并将导出属性明确设置为`true`。

4) 通过预定义白名单验证请求应用程序的证书。

5) 尽管意图是从伙伴应用程序发送的，仔细和安全地处理接收到的意图。

6) 只返回公开给伙伴应用的信息。

请参阅“4.1.3.2 验证和请求应用”，了解如何通过白名单验证应用。 此外，请参阅“5.2.1.3 如何验证应用证书的哈希”，了解如何验证白名单中指定目标应用的证书哈希。

AndroidManifest.xml





<div class="se-preview-section-delimiter"></div>

```xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    android:padding="5dp" >
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:text="@string/description" />
    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:onClick="onReturnResultClick"
        android:text="@string/return_result" />
</LinearLayout>

PartnerActivity.java

代码语言：javascript复制

package org.jssec.android.activity.partneractivity;

import org.jssec.android.shared.PkgCertWhitelists;
import org.jssec.android.shared.Utils;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

public class PartnerActivity extends Activity {

    // *** POINT 4 *** Verify the requesting application's certificate through a predefined whitelist.
    private static PkgCertWhitelists sWhitelists = null;

    private static void buildWhitelists(Context context) {
        boolean isdebug = Utils.isDebuggable(context);
        sWhitelists = new PkgCertWhitelists();
        // Register certificate hash value of partner application org.jssec.android.activity.partneruser
            .sWhitelists.add("org.jssec.android.activity.partneruser", isdebug ?
            // Certificate hash value of "androiddebugkey" in the debug.keystore.
            "0EFB7236 328348A9 89718BAD DF57F544 D5CCB4AE B9DB34BC 1E29DD26 F77C8255" :
            // Certificate hash value of "partner key" in the keystore.
            "1F039BB5 7861C27A 3916C778 8E78CE00 690B3974 3EB8259F E2627B8D 4C0EC35A");
            // Register the other partner applications in the same way.
    }

    private static boolean checkPartner(Context context, String pkgname) {
        if (sWhitelists == null) buildWhitelists(context);
        return sWhitelists.test(context, pkgname);
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // *** POINT 4 *** Verify the requesting application's certificate through a predefined whitelist.
        if (!checkPartner(this, getCallingActivity().getPackageName())) {
            Toast.makeText(this,
                "Requesting application is not a partner application.",
                Toast.LENGTH_LONG).show();
            finish();
            return;
        }
        // *** POINT 5 *** Handle the received intent carefully and securely, even though the intent was sent from a partner application.
        // Omitted, since this is a sample. Refer to "3.2 Handling Input Data Carefully and Securely."
        Toast.makeText(this, "Accessed by Partner App", Toast.LENGTH_LONG).show();
    }

    public void onReturnResultClick(View view) {
        // *** POINT 6 *** Only return Information that is granted to be disclosed to a partner application.
        Intent intent = new Intent();
        intent.putExtra("RESULT", "Information for partner applications");
        setResult(RESULT_OK, intent);
        finish();
    }
}

PkgCertWhitelists.java

代码语言：javascript复制

package org.jssec.android.shared;

import java.util.HashMap;
import java.util.Map;
import android.content.Context;

public class PkgCertWhitelists {

    private Map<String, String> mWhitelists = new HashMap<String, String>();

    public boolean add(String pkgname, String sha256) {
        if (pkgname == null) return false;
        if (sha256 == null) return false;
        sha256 = sha256.replaceAll(" ", "");
        if (sha256.length() != 64) return false; // SHA-256 -> 32 bytes -> 64 chars
        sha256 = sha256.toUpperCase();
        if (sha256.replaceAll("[0-9A-F] ", "").length() != 0) return false; // found non hex char
        mWhitelists.put(pkgname, sha256);
        return true;
    }

    public boolean test(Context ctx, String pkgname) {
        // Get the correct hash value which corresponds to pkgname.
        String correctHash = mWhitelists.get(pkgname);
        // Compare the actual hash value of pkgname with the correct hash value.
        return PkgCert.test(ctx, pkgname, correctHash);
    }
}

PkgCert.java

代码语言：javascript复制

package org.jssec.android.shared;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import android.content.Context;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.pm.Signature;

public class PkgCert {

    public static boolean test(Context ctx, String pkgname, String correctHash) {
        if (correctHash == null) return false;
        correctHash = correctHash.replaceAll(" ", "");
        return correctHash.equals(hash(ctx, pkgname));
    }

    public static String hash(Context ctx, String pkgname) {
        if (pkgname == null) return null;
        try {
            PackageManager pm = ctx.getPackageManager();
            PackageInfo pkginfo = pm.getPackageInfo(pkgname, PackageManager.GET_SIGNATURES);
            if (pkginfo.signatures.length != 1) return null; // Will not handle multiple signatures.
            Signature sig = pkginfo.signatures[0];
            byte[] cert = sig.toByteArray();
            byte[] sha256 = computeSha256(cert);
            return byte2hex(sha256);
        } catch (NameNotFoundException e) {
            return null;
        }
    }

    private static byte[] computeSha256(byte[] data) {
        try {
            return MessageDigest.getInstance("SHA-256").digest(data);
        } catch (NoSuchAlgorithmException e) {
            return null;
        }
    }

    private static String byte2hex(byte[] data) {
        if (data == null) return null;
        final StringBuilder hexadecimal = new StringBuilder();
        for (final byte b : data) {
            hexadecimal.append(String.format("X", b));
        }
        return hexadecimal.toString();
    }
}

使用伙伴活动的示例代码如下：

7) 验证目标应用的证书是否已在白名单中注册。

8) 不要为启动活动的意图设置FLAG_ACTIVITY_NEW_TASK标志。

9) 仅通过putExtra()发送公开给伙伴活动的信息。

10) 使用显示意图调用伙伴活动。

11) 使用startActivityForResult()来调用伙伴活动。

12) 即使数据来自伙伴应用程序，也要小心并安全地处理收到的结果数据。

请参阅“4.1.3.2 验证请求应用”了解如何通过白名单验证应用程序。 另请参阅“5.2.1.3 如何验证应用证书的哈希”，了解如何验证白名单中指定目标应用的证书哈希。

AndroidManifest.xml

代码语言：javascript复制

<?xml version="1.0" encoding="utf-8"?>
    <manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="org.jssec.android.activity.partneruser" >

    <application
        android:allowBackup="false"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >

        <activity
            android:name="org.jssec.android.activity.partneruser.PartnerUserActivity"
            android:label="@string/app_name"
            android:exported="true" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>

PartnerUserActivity.java

代码语言：javascript复制

package org.jssec.android.activity.partneruser;

import org.jssec.android.shared.PkgCertWhitelists;
import org.jssec.android.shared.Utils;
import android.app.Activity;
import android.content.ActivityNotFoundException;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

public class PartnerUserActivity extends Activity {

    // *** POINT 7 *** Verify if the certificate of a target application has been registered in a whitelist.
    private static PkgCertWhitelists sWhitelists = null;

    private static void buildWhitelists(Context context) {
        boolean isdebug = Utils.isDebuggable(context);
        sWhitelists = new PkgCertWhitelists();
        // Register the certificate hash value of partner application org.jssec.android.activity.partner
        activity
            .sWhitelists.add("org.jssec.android.activity.partneractivity", isdebug ?
            // The certificate hash value of "androiddebugkey" is in debug.keystore.
            "0EFB7236 328348A9 89718BAD DF57F544 D5CCB4AE B9DB34BC 1E29DD26 F77C8255" :
            // The certificate hash value of "my company key" is in the keystore.
            "D397D343 A5CBC10F 4EDDEB7C A10062DE 5690984F 1FB9E88B D7B3A7C2 42E142CA");
            // Register the other partner applications in the same way.
    }

    private static boolean checkPartner(Context context, String pkgname) {
        if (sWhitelists == null) buildWhitelists(context);
        return sWhitelists.test(context, pkgname);
    }

    private static final int REQUEST_CODE = 1;
    // Information related the target partner activity
    private static final String TARGET_PACKAGE = "org.jssec.android.activity.partneractivity";
    private static final String TARGET_ACTIVITY = "org.jssec.android.activity.partneractivity.PartnerActivity";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }

    public void onUseActivityClick(View view) {
        // *** POINT 7 *** Verify if the certificate of the target application has been registered in the own white list.
        if (!checkPartner(this, TARGET_PACKAGE)) {
            Toast.makeText(this, "Target application is not a partner application.", Toast.LENGTH_LONG).show();
            return;
        }
        try {
            // *** POINT 8 *** Do not set the FLAG_ACTIVITY_NEW_TASK flag for the intent that start an activity.
            Intent intent = new Intent();
            // *** POINT 9 *** Only send information that is granted to be disclosed to a Partner Activity only by putExtra().
            intent.putExtra("PARAM", "Info for Partner Apps");
            // *** POINT 10 *** Use explicit intent to call a Partner Activity.
            intent.setClassName(TARGET_PACKAGE, TARGET_ACTIVITY);
            // *** POINT 11 *** Use startActivityForResult() to call a Partner Activity.
            startActivityForResult(intent, REQUEST_CODE);
        }
        catch (ActivityNotFoundException e) {
            Toast.makeText(this, "Target activity not found.", Toast.LENGTH_LONG).show();
        }
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode != RESULT_OK) return;
        switch (requestCode) {
            case REQUEST_CODE:
                String result = data.getStringExtra("RESULT");
                // *** POINT 12 *** Handle the received data carefully and securely,
                // even though the data comes from a partner application.
                // Omitted, since this is a sample. Please refer to "3.2 Handling Input Data Carefully and Securely."
                Toast.makeText(this,
                    String.format("Received result: ¥"%s¥"", result), Toast.LENGTH_LONG).show();
                break;
        }
    }
}

PkgCertWhitelists.java

代码语言：javascript复制

package org.jssec.android.shared;

import java.util.HashMap;
import java.util.Map;
import android.content.Context;

public class PkgCertWhitelists {
    private Map<String, String> mWhitelists = new HashMap<String, String>();

    public boolean add(String pkgname, String sha256) {
        if (pkgname == null) return false;
        if (sha256 == null) return false;
        sha256 = sha256.replaceAll(" ", "");
        if (sha256.length() != 64) return false; // SHA-256 -> 32 bytes -> 64 chars
        sha256 = sha256.toUpperCase();
        if (sha256.replaceAll("[0-9A-F] ", "").length() != 0) return false; // found non hex char
        mWhitelists.put(pkgname, sha256);
        return true;
    }

    public boolean test(Context ctx, String pkgname) {
        // Get the correct hash value which corresponds to pkgname.
        String correctHash = mWhitelists.get(pkgname);
        // Compare the actual hash value of pkgname with the correct hash value.
        return PkgCert.test(ctx, pkgname, correctHash);
    }
}

PkgCert.java

代码语言：javascript复制

package org.jssec.android.shared;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import android.content.Context;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.pm.Signature;

public class PkgCert {
        public static boolean test(Context ctx, String pkgname, String correctHash) {
        if (correctHash == null) return false;
        correctHash = correctHash.replaceAll(" ", "");
        return correctHash.equals(hash(ctx, pkgname));
    }

    public static String hash(Context ctx, String pkgname) {
        if (pkgname == null) return null;
        try {
            PackageManager pm = ctx.getPackageManager();
            PackageInfo pkginfo = pm.getPackageInfo(pkgname, PackageManager.GET_SIGNATURES);
            if (pkginfo.signatures.length != 1) return null; // Will not handle multiple signatures.
            Signature sig = pkginfo.signatures[0];
            byte[] cert = sig.toByteArray();
            byte[] sha256 = computeSha256(cert);
            return byte2hex(sha256);
        } catch (NameNotFoundException e) {
            return null;
        }
    }

    private static byte[] computeSha256(byte[] data) {
        try {
            return MessageDigest.getInstance("SHA-256").digest(data);
        } catch (NoSuchAlgorithmException e) {
            return null;
        }
    }

    private static String byte2hex(byte[] data) {
        if (data == null) return null;
        final StringBuilder hexadecimal = new StringBuilder();
        for (final byte b : data) {
            hexadecimal.append(String.format("X", b));
        }
        return hexadecimal.toString();
    }
}

4.1.1.4 创建/使用内部活动

内部活动是禁止其他内部应用以外的应用使用的活动。 它们用于内部开发的应用，以便安全地共享信息和功能。

第三方应用可能会读取用于启动活动的意图。 因此，如果你将敏感信息放入用于启动活动的意图中，有必要采取对策来确保它不会被恶意第三方读取。

下面展示了创建内部活动的示例代码。

要点（创建活动）：

1) 定义内部签名权限。

2) 不要指定taskAffinity。

3) 不要指定launchMode。

4) 需要内部签名权限。

5) 不要定义意图过滤器，并将导出属性显式设为true。

6) 确认内部签名权限是由内部应用的。

7) 尽管意图是从内部应用发送的，仔细和安全地处理接收到的意图。

8) 由于请求的应用是内部的，因此可以返回敏感信息。

9) 导出 APK 时，请使用与目标应用相同的开发人员密钥对 APK 进行签名。

AndroidManifest.xml

代码语言：javascript复制

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="org.jssec.android.activity.inhouseactivity" >

    <!-- *** POINT 1 *** Define an in-house signature permission -->
    <permission
    android:name="org.jssec.android.activity.inhouseactivity.MY_PERMISSION"
    android:protectionLevel="signature" />

    <application
        android:allowBackup="false"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >

        <!-- In-house Activity -->
        <!-- *** POINT 2 *** Do not specify taskAffinity -->
        <!-- *** POINT 3 *** Do not specify launchMode -->
        <!-- *** POINT 4 *** Require the in-house signature permission -->
        <!-- *** POINT 5 *** Do not define the intent filter and explicitly set the exported attribute to
        true -->
        <activity
            android:name="org.jssec.android.activity.inhouseactivity.InhouseActivity"
            android:exported="true"
            android:permission="org.jssec.android.activity.inhouseactivity.MY_PERMISSION" />
    </application>
</manifest>

InhouseActivity.java

代码语言：javascript复制

package org.jssec.android.activity.inhouseactivity;

import org.jssec.android.shared.SigPerm;
import org.jssec.android.shared.Utils;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

public class InhouseActivity extends Activity {

    // In-house Signature Permission
    private static final String MY_PERMISSION = "org.jssec.android.activity.inhouseactivity.MY_PERMISSION";
    // In-house certificate hash value
    private static String sMyCertHash = null;

    private static String myCertHash(Context context) {
        if (sMyCertHash == null) {
            if (Utils.isDebuggable(context)) {
                // Certificate hash value of "androiddebugkey" in the debug.keystore.
                sMyCertHash = "0EFB7236 328348A9 89718BAD DF57F544 D5CCB4AE B9DB34BC 1E29DD26 F77C8255";
            } else {
                // Certificate hash value of "my company key" in the keystore.
                sMyCertHash = "D397D343 A5CBC10F 4EDDEB7C A10062DE 5690984F 1FB9E88B D7B3A7C2 42E142CA";
            }
        }
        return sMyCertHash;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        // *** POINT 6 *** Verify that the in-house signature permission is defined by an in-house application.
        if (!SigPerm.test(this, MY_PERMISSION, myCertHash(this))) {
            Toast.makeText(this, "The in-house signature permission is not declared by in-house application.",
            Toast.LENGTH_LONG).show();
            finish();
            return;
        }
        // *** POINT 7 *** Handle the received intent carefully and securely, even though the intent was sent from an in-house application.
        // Omitted, since this is a sample. Please refer to "3.2 Handling Input Data Carefully and Securely."
        String param = getIntent().getStringExtra("PARAM");
        Toast.makeText(this, String.format("Received param: ¥"%s¥"", param), Toast.LENGTH_LONG).show();
    }

    public void onReturnResultClick(View view) {
        // *** POINT 8 *** Sensitive information can be returned since the requesting application is inhouse.
        Intent intent = new Intent();
        intent.putExtra("RESULT", "Sensitive Info");
        setResult(RESULT_OK, intent);
        finish();
    }
}

SigPerm.java

代码语言：javascript复制

package org.jssec.android.shared;

import android.content.Context;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.pm.PermissionInfo;

public class SigPerm {

    public static boolean test(Context ctx, String sigPermName, String correctHash) {
        if (correctHash == null) return false;
        correctHash = correctHash.replaceAll(" ", "");
        return correctHash.equals(hash(ctx, sigPermName));
    }

    public static String hash(Context ctx, String sigPermName) {
        if (sigPermName == null) return null;
        try {
            // Get the package name of the application which declares a permission named sigPermName.
            PackageManager pm = ctx.getPackageManager();
            PermissionInfo pi;
            pi = pm.getPermissionInfo(sigPermName, PackageManager.GET_META_DATA);
            String pkgname = pi.packageName;
            // Fail if the permission named sigPermName is not a Signature Permission
            if (pi.protectionLevel != PermissionInfo.PROTECTION_SIGNATURE) return null;
            // Return the certificate hash value of the application which declares a permission named sigPermName.
            return PkgCert.hash(ctx, pkgname);
        } catch (NameNotFoundException e) {
            return null;
        }
    }
}

PkgCert.java

代码语言：javascript复制

package org.jssec.android.shared;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import android.content.Context;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.pm.Signature;

public class PkgCert {
    public static boolean test(Context ctx, String pkgname, String correctHash) {
        if (correctHash == null) return false;
        correctHash = correctHash.replaceAll(" ", "");
        return correctHash.equals(hash(ctx, pkgname));
    }

    public static String hash(Context ctx, String pkgname) {
        if (pkgname == null) return null;
        try {
            PackageManager pm = ctx.getPackageManager();
            PackageInfo pkginfo = pm.getPackageInfo(pkgname, PackageManager.GET_SIGNATURES);
            if (pkginfo.signatures.length != 1) return null; // Will not handle multiple signatures.
            Signature sig = pkginfo.signatures[0];
            byte[] cert = sig.toByteArray();
            byte[] sha256 = computeSha256(cert);
            return byte2hex(sha256);
        } catch (NameNotFoundException e) {
            return null;
        }
    }

    private static byte[] computeSha256(byte[] data) {
        try {
            return MessageDigest.getInstance("SHA-256").digest(data);
        } catch (NoSuchAlgorithmException e) {
            return null;
        }
    }

    private static String byte2hex(byte[] data) {
        if (data == null) return null;
        final StringBuilder hexadecimal = new StringBuilder();
        for (final byte b : data) {
            hexadecimal.append(String.format("X", b));
        }
        return hexadecimal.toString();
    }
}

要点 9：导出 APK 时，请使用与目标应用相同的开发人员密钥对 APK 进行签名。

使用内部活动的代码如下：

要点（使用活动）：

10) 声明你要使用内部签名权限。

11) 确认内部签名权限是由内部应用定义的。

12) 验证目标应用是否使用内部证书签名。

13) 由于目标应用是内部的，所以敏感信息只能由putExtra()发送。

14) 使用显式意图调用内部活动。

15) 即使数据来自内部应用，也要小心并安全地处理接收到的数据。

16) 导出 APK 时，请使用与目标应用相同的开发人员密钥对 APK 进行签名。

AndroidManifest.xml

代码语言：javascript复制

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="org.jssec.android.activity.inhouseuser" >

    <!-- *** POINT 10 *** Declare to use the in-house signature permission -->
    <uses-permission
    android:name="org.jssec.android.activity.inhouseactivity.MY_PERMISSION" />

    <application
        android:allowBackup="false"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >

        <activity
            android:name="org.jssec.android.activity.inhouseuser.InhouseUserActivity"
            android:label="@string/app_name"
            android:exported="true" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>

InhouseUserActivity.java

代码语言：javascript复制

package org.jssec.android.activity.inhouseuser;

import org.jssec.android.shared.PkgCert;
import org.jssec.android.shared.SigPerm;
import org.jssec.android.shared.Utils;
import android.app.Activity;
import android.content.ActivityNotFoundException;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

public class InhouseUserActivity extends Activity {

    // Target Activity information
    private static final String TARGET_PACKAGE = "org.jssec.android.activity.inhouseactivity";
    private static final String TARGET_ACTIVITY = "org.jssec.android.activity.inhouseactivity.InhouseActivity";
    // In-house Signature Permission
    private static final String MY_PERMISSION = "org.jssec.android.activity.inhouseactivity.MY_PERMISSION";
    // In-house certificate hash value
    private static String sMyCertHash = null;

    private static String myCertHash(Context context) {
        if (sMyCertHash == null) {
            if (Utils.isDebuggable(context)) {
                // Certificate hash value of "androiddebugkey" in the debug.keystore.
                sMyCertHash = "0EFB7236 328348A9 89718BAD DF57F544 D5CCB4AE B9DB34BC 1E29DD26 F77C8255";
            } else {
                // Certificate hash value of "my company key" in the keystore.
                sMyCertHash = "D397D343 A5CBC10F 4EDDEB7C A10062DE 5690984F 1FB9E88B D7B3A7C2 42E142CA";
            }
        }
        return sMyCertHash;
    }

    private static final int REQUEST_CODE = 1;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }

    public void onUseActivityClick(View view) {
        // *** POINT 11 *** Verify that the in-house signature permission is defined by an in-house application.
        if (!SigPerm.test(this, MY_PERMISSION, myCertHash(this))) {
            Toast.makeText(this, "The in-house signature permission is not declared by in-house application.",
            Toast.LENGTH_LONG).show();
            return;
        }
        // ** POINT 12 *** Verify that the destination application is signed with the in-house certificate.
        if (!PkgCert.test(this, TARGET_PACKAGE, myCertHash(this))) {
            Toast.makeText(this, "Target application is not an in-house application.", Toast.LENGTH_LONG).show();
            return;
        }
        try {
            Intent intent = new Intent();
            // *** POINT 13 *** Sensitive information can be sent only by putExtra() since the destination application is in-house.
            intent.putExtra("PARAM", "Sensitive Info");

            // *** POINT 14 *** Use explicit intents to call an In-house Activity.
            intent.setClassName(TARGET_PACKAGE, TARGET_ACTIVITY);
            startActivityForResult(intent, REQUEST_CODE);
        } catch (ActivityNotFoundException e) {
            Toast.makeText(this, "Target activity not found.", Toast.LENGTH_LONG).show();
        }
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode != RESULT_OK) return;
        switch (requestCode) {
            case REQUEST_CODE:
                String result = data.getStringExtra("RESULT");
                // *** POINT 15 *** Handle the received data carefully and securely,
                // even though the data came from an in-house application.
                // Omitted, since this is a sample. Please refer to "3.2 Handling Input Data Carefully and Securely."
                Toast.makeText(this, String.format("Received result: ¥"%s¥"", result), Toast.LENGTH_LONG).show();
                break;
        }
    }
}

SigPerm.java

代码语言：javascript复制

package org.jssec.android.shared;

import android.content.Context;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.pm.PermissionInfo;

public class SigPerm {

    public static boolean test(Context ctx, String sigPermName, String correctHash) {
        if (correctHash == null) return false;
        correctHash = correctHash.replaceAll(" ", "");
        return correctHash.equals(hash(ctx, sigPermName));
    }

    public static String hash(Context ctx, String sigPermName) {
        if (sigPermName == null) return null;
        try {
            // Get the package name of the application which declares a permission named sigPermName.
            PackageManager pm = ctx.getPackageManager();
            PermissionInfo pi;
            pi = pm.getPermissionInfo(sigPermName, PackageManager.GET_META_DATA);
            String pkgname = pi.packageName;
            // Fail if the permission named sigPermName is not a Signature Permission
            if (pi.protectionLevel != PermissionInfo.PROTECTION_SIGNATURE) return null;
            // Return the certificate hash value of the application which declares a permission named sigPermName.
            return PkgCert.hash(ctx, pkgname);
        } catch (NameNotFoundException e) {
            return null;
        }
    }
}

PkgCert.java

代码语言：javascript复制

package org.jssec.android.shared;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import android.content.Context;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.pm.Signature;

public class PkgCert {

    public static boolean test(Context ctx, String pkgname, String correctHash) {
        if (correctHash == null) return false;
        correctHash = correctHash.replaceAll(" ", "");
        return correctHash.equals(hash(ctx, pkgname));
    }

    public static String hash(Context ctx, String pkgname) {
        if (pkgname == null) return null;
        try {
            PackageManager pm = ctx.getPackageManager();
            PackageInfo pkginfo = pm.getPackageInfo(pkgname, PackageManager.GET_SIGNATURES);
            if (pkginfo.signatures.length != 1) return null; // Will not handle multiple signatures.
            Signature sig = pkginfo.signatures[0];
            byte[] cert = sig.toByteArray();
            byte[] sha256 = computeSha256(cert);
            return byte2hex(sha256);
        } catch (NameNotFoundException e) {
            return null;
        }
    }

    private static byte[] computeSha256(byte[] data) {
        try {
            return MessageDigest.getInstance("SHA-256").digest(data);
        } catch (NoSuchAlgorithmException e) {
            return null;
        }
    }

    private static String byte2hex(byte[] data) {
        if (data == null) return null;
        final StringBuilder hexadecimal = new StringBuilder();
        for (final byte b : data) {
            hexadecimal.append(String.format("X", b));
        }
        return hexadecimal.toString();
    }
}

要点 16：导出 APK 时，请使用与目标应用相同的开发人员密钥对 APK 进行签名。

java android 安全 xml

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