Started working on API demo app

org_apg/AndroidManifest.xml

@@ -4,9 +4,11 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     android:installLocation="auto"
     package="org.apg"
-    android:versionCode="11000"
+    android:versionCode="50"
     android:versionName="1.1" >
 
+    <!-- APG Plus starting with versionCode 50! -->
+
     <uses-sdk
         android:minSdkVersion="4"
         android:targetSdkVersion="14" />

org_apg_api_demo/.gitignore

@@ -0,0 +1,23 @@
+#Android generated
+bin
+gen
+obj
+libs/armeabi
+lint.xml
+local.properties
+
+#Eclipse
+.project
+.classpath
+.settings
+
+#IntelliJ IDEA
+.idea
+*.iml
+
+#Maven
+target
+release.properties
+
+#Mac
+.DS_Store

org_apg_api_demo/AndroidManifest.xml

@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="org.apg.api_demo"
+    android:versionCode="1"
+    android:versionName="1.0" >
+
+    <uses-sdk
+        android:minSdkVersion="4"
+        android:targetSdkVersion="14" />
+
+    <application
+        android:icon="@drawable/icon"
+        android:label="APG API Demo" >
+        <activity
+            android:name=".BaseActivity"
+            android:label="APG API Demo" >
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+        <activity
+            android:name=".IntentDemo1Activity"
+            android:label="Intent Demo 1" />
+    </application>
+
+</manifest>

org_apg_api_demo/proguard.cfg

@@ -0,0 +1,40 @@
+-optimizationpasses 5
+-dontusemixedcaseclassnames
+-dontskipnonpubliclibraryclasses
+-dontpreverify
+-verbose
+-optimizations !code/simplification/arithmetic,!field/*,!class/merging/*
+
+-keep public class * extends android.app.Activity
+-keep public class * extends android.app.Application
+-keep public class * extends android.app.Service
+-keep public class * extends android.content.BroadcastReceiver
+-keep public class * extends android.content.ContentProvider
+-keep public class * extends android.app.backup.BackupAgentHelper
+-keep public class * extends android.preference.Preference
+-keep public class com.android.vending.licensing.ILicensingService
+
+-keepclasseswithmembernames class * {
+    native <methods>;
+}
+
+-keepclasseswithmembers class * {
+    public <init>(android.content.Context, android.util.AttributeSet);
+}
+
+-keepclasseswithmembers class * {
+    public <init>(android.content.Context, android.util.AttributeSet, int);
+}
+
+-keepclassmembers class * extends android.app.Activity {
+   public void *(android.view.View);
+}
+
+-keepclassmembers enum * {
+    public static **[] values();
+    public static ** valueOf(java.lang.String);
+}
+
+-keep class * implements android.os.Parcelable {
+  public static final android.os.Parcelable$Creator *;
+}

org_apg_api_demo/project.properties

@@ -0,0 +1,11 @@
+# This file is automatically generated by Android Tools.
+# Do not modify this file -- YOUR CHANGES WILL BE ERASED!
+#
+# This file must be checked in Version Control Systems.
+#
+# To customize properties used by the Ant build system use,
+# "ant.properties", and override values to adapt the script to your
+# project structure.
+
+# Project target.
+target=android-15

org_apg_api_demo/res/layout/intent_demo_1.xml

@@ -0,0 +1,13 @@
+<?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" >
+
+    <Button
+        android:id="@+id/button1"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="send Intent" />
+
+</LinearLayout>

org_apg_api_demo/res/xml/base_preference.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8"?>
+<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" >
+
+
+    <PreferenceCategory android:title="Intent Demos" >
+        <Preference
+            android:key="intent_demo_1"
+            android:title="Intent Demo 1" />
+        <Preference
+            android:key="intent_demo_2"
+            android:title="Intent Demo 2" />
+    </PreferenceCategory>
+    <PreferenceCategory android:title="AIDL Demos" >
+                <Preference
+            android:key="aidl_demo"
+            android:title="AIDL Demo 1" />
+    </PreferenceCategory>
+
+
+</PreferenceScreen>

org_apg_api_demo/src/org/apg/api_demo/BaseActivity.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2012 Dominik Schürmann <dominik@dominikschuermann.de>
+ *
+ * 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 org.apg.api_demo;
+
+import org.apg.api_demo.R;
+
+import android.app.Activity;
+import android.content.Intent;
+import android.os.Bundle;
+import android.preference.Preference;
+import android.preference.Preference.OnPreferenceClickListener;
+import android.preference.PreferenceActivity;
+
+public class BaseActivity extends PreferenceActivity {
+    private Activity mActivity;
+
+    private Preference mIntentDemo;
+
+    /**
+     * Called when the activity is first created.
+     */
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        mActivity = this;
+
+        // load preferences from xml
+        addPreferencesFromResource(R.xml.base_preference);
+
+        // find preferences
+        mIntentDemo = (Preference) findPreference("intent_demo_1");
+
+        mIntentDemo.setOnPreferenceClickListener(new OnPreferenceClickListener() {
+            @Override
+            public boolean onPreferenceClick(Preference preference) {
+                startActivity(new Intent(mActivity, IntentDemo1Activity.class));
+
+                return false;
+            }
+        });
+
+    }
+}

org_apg_api_demo/src/org/apg/api_demo/IntentDemo1Activity.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2012 Dominik Schürmann <dominik@dominikschuermann.de>
+ *
+ * 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 org.apg.api_demo;
+
+import org.apg.api_demo.R;
+
+import android.app.Activity;
+import android.os.Bundle;
+
+public class IntentDemo1Activity extends Activity {
+    Activity mActivity;
+
+    /**
+     * Instantiate View for this Activity
+     */
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        setContentView(R.layout.intent_demo_1);
+
+        // org.apg.intent.SELECT_PUBLIC_KEYS
+
+        // get back:
+        // long[] selectedKeyIds data.putExtra(Apg.EXTRA_SELECTION, selectedKeyIds);
+        // String[] userIds data.putExtra(Apg.EXTRA_USER_IDS, userIds.toArray(userIdArray));
+
+        mActivity = this;
+    }
+}

org_apg_api_demo/src/org/apg/api_demo/util/Constants.java

@@ -0,0 +1,70 @@
+package org.apg.api_demo.util;
+
+import java.util.regex.Pattern;
+
+import android.net.Uri;
+
+public class Constants {
+    public static final String NAME = "apg";
+
+    public static final String APG_PACKAGE_NAME = "org.apg";
+    public static final int MIN_REQUIRED_VERSION = 50;
+
+    public static final String AUTHORITY = "org.apg.provider";
+    public static final Uri CONTENT_URI_SECRET_KEY_RING_BY_KEY_ID = Uri.parse("content://"
+            + AUTHORITY + "/key_rings/secret/key_id/");
+    public static final Uri CONTENT_URI_SECRET_KEY_RING_BY_EMAILS = Uri.parse("content://"
+            + AUTHORITY + "/key_rings/secret/emails/");
+
+    public static final Uri CONTENT_URI_PUBLIC_KEY_RING_BY_KEY_ID = Uri.parse("content://"
+            + AUTHORITY + "/key_rings/public/key_id/");
+    public static final Uri CONTENT_URI_PUBLIC_KEY_RING_BY_EMAILS = Uri.parse("content://"
+            + AUTHORITY + "/key_rings/public/emails/");
+
+    public static class Intent {
+        public static final String DECRYPT = APG_PACKAGE_NAME + ".intent.DECRYPT";
+        public static final String ENCRYPT = APG_PACKAGE_NAME + ".intent.ENCRYPT";
+        public static final String DECRYPT_FILE = APG_PACKAGE_NAME + ".intent.DECRYPT_FILE";
+        public static final String ENCRYPT_FILE = APG_PACKAGE_NAME + ".intent.ENCRYPT_FILE";
+        public static final String DECRYPT_AND_RETURN = APG_PACKAGE_NAME
+                + ".intent.DECRYPT_AND_RETURN";
+        public static final String ENCRYPT_AND_RETURN = APG_PACKAGE_NAME
+                + ".intent.ENCRYPT_AND_RETURN";
+        public static final String SELECT_PUBLIC_KEYS = APG_PACKAGE_NAME
+                + ".intent.SELECT_PUBLIC_KEYS";
+        public static final String SELECT_SECRET_KEY = APG_PACKAGE_NAME
+                + ".intent.SELECT_SECRET_KEY";
+    }
+
+    public static final String EXTRA_TEXT = "text";
+    public static final String EXTRA_DATA = "data";
+    public static final String EXTRA_ERROR = "error";
+    public static final String EXTRA_DECRYPTED_MESSAGE = "decryptedMessage";
+    public static final String EXTRA_ENCRYPTED_MESSAGE = "encryptedMessage";
+    public static final String EXTRA_SIGNATURE = "signature";
+    public static final String EXTRA_SIGNATURE_KEY_ID = "signatureKeyId";
+    public static final String EXTRA_SIGNATURE_USER_ID = "signatureUserId";
+    public static final String EXTRA_SIGNATURE_SUCCESS = "signatureSuccess";
+    public static final String EXTRA_SIGNATURE_UNKNOWN = "signatureUnknown";
+    public static final String EXTRA_USER_ID = "userId";
+    public static final String EXTRA_KEY_ID = "keyId";
+    public static final String EXTRA_ENCRYPTION_KEY_IDS = "encryptionKeyIds";
+    public static final String EXTRA_SELECTION = "selection";
+    public static final String EXTRA_MESSAGE = "message";
+    public static final String EXTRA_INTENT_VERSION = "intentVersion";
+
+    public static final String INTENT_VERSION = "1";
+
+    public static final int DECRYPT_MESSAGE = 0x21070001;
+    public static final int ENCRYPT_MESSAGE = 0x21070002;
+    public static final int SELECT_PUBLIC_KEYS = 0x21070003;
+    public static final int SELECT_SECRET_KEY = 0x21070004;
+
+    // public static Pattern PGP_MESSAGE = Pattern.compile(
+    // ".*?(-----BEGIN PGP MESSAGE-----.*?-----END PGP MESSAGE-----).*", Pattern.DOTALL);
+
+    // public static Pattern PGP_SIGNED_MESSAGE = Pattern
+    // .compile(
+    // ".*?(-----BEGIN PGP SIGNED MESSAGE-----.*?-----BEGIN PGP SIGNATURE-----.*?-----END PGP SIGNATURE-----).*",
+    // Pattern.DOTALL);
+}

org_apg_api_demo/src/org/apg/api_demo/util/IntentHelper.java

@@ -0,0 +1,216 @@
+package org.apg.api_demo.util;
+
+import android.app.Activity;
+import android.content.ActivityNotFoundException;
+import android.content.Intent;
+import android.widget.Toast;
+
+public class IntentHelper {
+
+    /**
+     * Select the signature key.
+     * 
+     * @param activity
+     * @param pgpData
+     * @return success or failure
+     */
+    public boolean selectSecretKey(Activity activity) {
+        android.content.Intent intent = new android.content.Intent(
+                Constants.Intent.SELECT_SECRET_KEY);
+        intent.putExtra(Constants.EXTRA_INTENT_VERSION, Constants.INTENT_VERSION);
+        try {
+            activity.startActivityForResult(intent, Constants.SELECT_SECRET_KEY);
+            return true;
+        } catch (ActivityNotFoundException e) {
+            activityNotFound(activity);
+            return false;
+        }
+    }
+
+    /**
+     * Start the encrypt activity.
+     * 
+     * @param activity
+     * @param data
+     * @param pgpData
+     * @return success or failure
+     */
+    public boolean encrypt(Activity activity, String data, long[] encryptionKeyIds,
+            long signatureKeyId) {
+        android.content.Intent intent = new android.content.Intent(
+                Constants.Intent.ENCRYPT_AND_RETURN);
+        intent.putExtra(Constants.EXTRA_INTENT_VERSION, Constants.INTENT_VERSION);
+        intent.setType("text/plain");
+        intent.putExtra(Constants.EXTRA_TEXT, data);
+        intent.putExtra(Constants.EXTRA_ENCRYPTION_KEY_IDS, encryptionKeyIds);
+        intent.putExtra(Constants.EXTRA_SIGNATURE_KEY_ID, signatureKeyId);
+        try {
+            activity.startActivityForResult(intent, Constants.ENCRYPT_MESSAGE);
+            return true;
+        } catch (ActivityNotFoundException e) {
+            activityNotFound(activity);
+            return false;
+        }
+    }
+
+    /**
+     * Start the decrypt activity.
+     * 
+     * @param activity
+     * @param data
+     * @param pgpData
+     * @return success or failure
+     */
+    public boolean decrypt(Activity activity, String data) {
+        android.content.Intent intent = new android.content.Intent(
+                Constants.Intent.DECRYPT_AND_RETURN);
+        intent.putExtra(Constants.EXTRA_INTENT_VERSION, Constants.INTENT_VERSION);
+        intent.setType("text/plain");
+        if (data == null) {
+            return false;
+        }
+        try {
+            intent.putExtra(Constants.EXTRA_TEXT, data);
+            activity.startActivityForResult(intent, Constants.DECRYPT_MESSAGE);
+            return true;
+        } catch (ActivityNotFoundException e) {
+            activityNotFound(activity);
+            return false;
+        }
+    }
+
+    private void activityNotFound(Activity activity) {
+        Toast.makeText(activity, "APG Activity not found! Is APG installed correctly?",
+                Toast.LENGTH_LONG).show();
+    }
+
+    /**
+     * Handle the activity results that concern us.
+     * 
+     * @param activity
+     * @param requestCode
+     * @param resultCode
+     * @param data
+     * @return handled or not
+     */
+    public boolean onActivityResult(Activity activity, int requestCode, int resultCode, Intent data) {
+        switch (requestCode) {
+        case Constants.SELECT_SECRET_KEY:
+            // if (resultCode != Activity.RESULT_OK || data == null) {
+            // break;
+            // }
+            // pgpData.setSignatureKeyId(data.getLongExtra(Apg.EXTRA_KEY_ID, 0));
+            // pgpData.setSignatureUserId(data.getStringExtra(Apg.EXTRA_USER_ID));
+            // ((MessageCompose) activity).updateEncryptLayout();
+            break;
+
+        case Constants.SELECT_PUBLIC_KEYS:
+            // if (resultCode != Activity.RESULT_OK || data == null) {
+            // pgpData.setEncryptionKeys(null);
+            // ((MessageCompose) activity).onEncryptionKeySelectionDone();
+            // break;
+            // }
+            // pgpData.setEncryptionKeys(data.getLongArrayExtra(Apg.EXTRA_SELECTION));
+            // ((MessageCompose) activity).onEncryptionKeySelectionDone();
+            break;
+
+        case Constants.ENCRYPT_MESSAGE:
+            // if (resultCode != Activity.RESULT_OK || data == null) {
+            // pgpData.setEncryptionKeys(null);
+            // ((MessageCompose) activity).onEncryptDone();
+            // break;
+            // }
+            // pgpData.setEncryptedData(data.getStringExtra(Apg.EXTRA_ENCRYPTED_MESSAGE));
+            // // this was a stupid bug in an earlier version, just gonna leave this in for an APG
+            // // version or two
+            // if (pgpData.getEncryptedData() == null) {
+            // pgpData.setEncryptedData(data.getStringExtra(Apg.EXTRA_DECRYPTED_MESSAGE));
+            // }
+            // if (pgpData.getEncryptedData() != null) {
+            // ((MessageCompose) activity).onEncryptDone();
+            // }
+            break;
+
+        case Constants.DECRYPT_MESSAGE:
+            if (resultCode != Activity.RESULT_OK || data == null) {
+                break;
+            }
+
+            // pgpData.setSignatureUserId(data.getStringExtra(Apg.EXTRA_SIGNATURE_USER_ID));
+            // pgpData.setSignatureKeyId(data.getLongExtra(Apg.EXTRA_SIGNATURE_KEY_ID, 0));
+            // pgpData.setSignatureSuccess(data.getBooleanExtra(Apg.EXTRA_SIGNATURE_SUCCESS,
+            // false));
+            // pgpData.setSignatureUnknown(data.getBooleanExtra(Apg.EXTRA_SIGNATURE_UNKNOWN,
+            // false));
+            //
+            // pgpData.setDecryptedData(data.getStringExtra(Apg.EXTRA_DECRYPTED_MESSAGE));
+            // ((MessageView) activity).onDecryptDone(pgpData);
+
+            break;
+
+        default:
+            return false;
+        }
+
+        return true;
+    }
+
+    //
+    // /**
+    // * Select encryption keys.
+    // *
+    // * @param activity
+    // * @param emails
+    // * The emails that should be used for preselection.
+    // * @param pgpData
+    // * @return success or failure
+    // */
+    // public boolean selectEncryptionKeys(Activity activity, String emails) {
+    // android.content.Intent intent = new android.content.Intent(Apg.Intent.SELECT_PUBLIC_KEYS);
+    // intent.putExtra(EXTRA_INTENT_VERSION, INTENT_VERSION);
+    // long[] initialKeyIds = null;
+    // if (!pgpData.hasEncryptionKeys()) {
+    // List<Long> keyIds = new ArrayList<Long>();
+    // if (pgpData.hasSignatureKey()) {
+    // keyIds.add(pgpData.getSignatureKeyId());
+    // }
+    //
+    // try {
+    // Uri contentUri = Uri.withAppendedPath(Apg.CONTENT_URI_PUBLIC_KEY_RING_BY_EMAILS,
+    // emails);
+    // Cursor c = activity.getContentResolver().query(contentUri,
+    // new String[] { "master_key_id" }, null, null, null);
+    // if (c != null) {
+    // while (c.moveToNext()) {
+    // keyIds.add(c.getLong(0));
+    // }
+    // }
+    //
+    // if (c != null) {
+    // c.close();
+    // }
+    // } catch (SecurityException e) {
+    // Toast.makeText(activity,
+    // activity.getResources().getString(R.string.insufficient_apg_permissions),
+    // Toast.LENGTH_LONG).show();
+    // }
+    // if (!keyIds.isEmpty()) {
+    // initialKeyIds = new long[keyIds.size()];
+    // for (int i = 0, size = keyIds.size(); i < size; ++i) {
+    // initialKeyIds[i] = keyIds.get(i);
+    // }
+    // }
+    // } else {
+    // initialKeyIds = pgpData.getEncryptionKeys();
+    // }
+    // intent.putExtra(Apg.EXTRA_SELECTION, initialKeyIds);
+    // try {
+    // activity.startActivityForResult(intent, Apg.SELECT_PUBLIC_KEYS);
+    // return true;
+    // } catch (ActivityNotFoundException e) {
+    // Toast.makeText(activity, R.string.error_activity_not_found, Toast.LENGTH_SHORT).show();
+    // return false;
+    // }
+    // }
+
+}

org_apg_api_demo/src/org/apg/api_demo/util/ProviderHelper.java

@@ -0,0 +1,164 @@
+package org.apg.api_demo.util;
+
+import android.content.ContentUris;
+import android.content.Context;
+import android.database.Cursor;
+import android.net.Uri;
+import android.widget.Toast;
+
+public class ProviderHelper {
+
+    /**
+     * Get secret key ids based on a given email.
+     * 
+     * @param context
+     * @param email
+     *            The email in question.
+     * @return key ids
+     */
+    public long[] getSecretKeyIdsFromEmail(Context context, String email) {
+        long ids[] = null;
+        try {
+            Uri contentUri = Uri.withAppendedPath(Constants.CONTENT_URI_SECRET_KEY_RING_BY_EMAILS,
+                    email);
+            Cursor c = context.getContentResolver().query(contentUri,
+                    new String[] { "master_key_id" }, null, null, null);
+            if (c != null && c.getCount() > 0) {
+                ids = new long[c.getCount()];
+                while (c.moveToNext()) {
+                    ids[c.getPosition()] = c.getLong(0);
+                }
+            }
+
+            if (c != null) {
+                c.close();
+            }
+        } catch (SecurityException e) {
+            insufficientPermissionsInfo(context);
+        }
+
+        return ids;
+    }
+
+    /**
+     * Get public key ids based on a given email.
+     * 
+     * @param context
+     * @param email
+     *            The email in question.
+     * @return key ids
+     */
+    public long[] getPublicKeyIdsFromEmail(Context context, String email) {
+        long ids[] = null;
+        try {
+            Uri contentUri = Uri.withAppendedPath(Constants.CONTENT_URI_PUBLIC_KEY_RING_BY_EMAILS,
+                    email);
+            Cursor c = context.getContentResolver().query(contentUri,
+                    new String[] { "master_key_id" }, null, null, null);
+            if (c != null && c.getCount() > 0) {
+                ids = new long[c.getCount()];
+                while (c.moveToNext()) {
+                    ids[c.getPosition()] = c.getLong(0);
+                }
+            }
+
+            if (c != null) {
+                c.close();
+            }
+        } catch (SecurityException e) {
+            insufficientPermissionsInfo(context);
+        }
+
+        return ids;
+    }
+
+    /**
+     * Find out if a given email has a secret key.
+     * 
+     * @param context
+     * @param email
+     *            The email in question.
+     * @return true if there is a secret key for this email.
+     */
+    public boolean hasSecretKeyForEmail(Context context, String email) {
+        try {
+            Uri contentUri = Uri.withAppendedPath(Constants.CONTENT_URI_SECRET_KEY_RING_BY_EMAILS,
+                    email);
+            Cursor c = context.getContentResolver().query(contentUri,
+                    new String[] { "master_key_id" }, null, null, null);
+            if (c != null && c.getCount() > 0) {
+                c.close();
+                return true;
+            }
+            if (c != null) {
+                c.close();
+            }
+        } catch (SecurityException e) {
+            insufficientPermissionsInfo(context);
+        }
+        return false;
+    }
+
+    /**
+     * Find out if a given email has a public key.
+     * 
+     * @param context
+     * @param email
+     *            The email in question.
+     * @return true if there is a public key for this email.
+     */
+    public boolean hasPublicKeyForEmail(Context context, String email) {
+        try {
+            Uri contentUri = Uri.withAppendedPath(Constants.CONTENT_URI_PUBLIC_KEY_RING_BY_EMAILS,
+                    email);
+            Cursor c = context.getContentResolver().query(contentUri,
+                    new String[] { "master_key_id" }, null, null, null);
+            if (c != null && c.getCount() > 0) {
+                c.close();
+                return true;
+            }
+            if (c != null) {
+                c.close();
+            }
+        } catch (SecurityException e) {
+            insufficientPermissionsInfo(context);
+        }
+        return false;
+    }
+
+    /**
+     * Get the user id based on the key id.
+     * 
+     * @param context
+     * @param keyId
+     * @return user id
+     */
+    public String getUserId(Context context, long keyId) {
+        String userId = null;
+        try {
+            Uri contentUri = ContentUris.withAppendedId(
+                    Constants.CONTENT_URI_SECRET_KEY_RING_BY_KEY_ID, keyId);
+            Cursor c = context.getContentResolver().query(contentUri, new String[] { "user_id" },
+                    null, null, null);
+            if (c != null && c.moveToFirst()) {
+                userId = c.getString(0);
+            }
+
+            if (c != null) {
+                c.close();
+            }
+        } catch (SecurityException e) {
+            insufficientPermissionsInfo(context);
+        }
+
+        if (userId == null) {
+            userId = "unknown";
+        }
+        return userId;
+    }
+
+    private void insufficientPermissionsInfo(Context context) {
+        Toast.makeText(context, "Permission to access APG Provider is missing!", Toast.LENGTH_LONG)
+                .show();
+    }
+}

org_apg_api_demo/src/org/apg/api_demo/util/Util.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2010-2011 K9-Mail Contributors
+ * Copyright (C) 2012 Dominik Schürmann <dominik@dominikschuermann.de>
+ *
+ * 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 org.apg.api_demo.util;
+
+import android.content.Context;
+import android.content.pm.PackageInfo;
+import android.content.pm.PackageManager.NameNotFoundException;
+
+import android.widget.Toast;
+
+public class Util {
+
+    /**
+     * Check whether APG is installed and at a high enough version.
+     * 
+     * @param context
+     * @return whether a suitable version of APG was found
+     */
+    public boolean isApgAvailable(Context context) {
+        try {
+            PackageInfo pi = context.getPackageManager().getPackageInfo(Constants.APG_PACKAGE_NAME,
+                    0);
+            if (pi.versionCode >= Constants.MIN_REQUIRED_VERSION) {
+                return true;
+            } else {
+                Toast.makeText(context,
+                        "This APG version is not supported! Please update to a newer one!",
+                        Toast.LENGTH_LONG).show();
+            }
+        } catch (NameNotFoundException e) {
+            // not found
+        }
+
+        return false;
+    }
+}