4.1.1.4 创建/使用内部活动
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2023-12-01
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):
定义内部签名权限。
不要指定
taskAffinity
。不要指定
launchMode
。需要内部签名权限。
不要定义意图过滤器,并将导出属性显式设为
true
。确认内部签名权限是由内部应用的。
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。
由于请求的应用是内部的,因此可以返回敏感信息。
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
<?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
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
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
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("%02X", 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):
声明你要使用内部签名权限。
确认内部签名权限是由内部应用定义的。
验证目标应用是否使用内部证书签名。
由于目标应用是内部的,所以敏感信息只能由
putExtra()
发送。使用显式意图调用内部活动。
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。
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
<?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
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
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
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("%02X", 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。