Merge from apg-integration

AndroidManifest.xml

@@ -22,6 +22,8 @@
     <uses-permission android:name="android.permission.VIBRATE"/>
     <uses-permission android:name="android.permission.WAKE_LOCK"/>
     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
+    <uses-permission android:name="org.thialfihar.android.apg.permission.READ_KEY_DETAILS" />
+
     <permission android:name="com.fsck.k9.permission.READ_ATTACHMENT"
                 android:permissionGroup="android.permission-group.MESSAGES"
                 android:protectionLevel="dangerous"

res/layout/message_compose.xml

@@ -1,8 +1,8 @@
 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
-	android:layout_width="fill_parent"
+    android:layout_width="fill_parent"
     android:layout_height="fill_parent"
-	android:orientation="vertical"
+    android:orientation="vertical"
     android:background="#ffffff" >
 
     <ScrollView
@@ -70,6 +70,66 @@
                     android:textAppearance="?android:attr/textAppearanceMedium"
                     android:visibility="gone" />
 
+                <LinearLayout
+                    android:id="@+id/layout_encrypt"
+                    android:orientation="horizontal"
+                    android:layout_width="fill_parent"
+                    android:layout_height="wrap_content"
+                    android:visibility="gone"
+                    android:paddingLeft="6dip"
+                    android:paddingRight="6dip">
+
+                    <LinearLayout
+                        android:orientation="horizontal"
+                        android:layout_gravity="center_vertical"
+                        android:layout_width="0dip"
+                        android:layout_height="wrap_content"
+                        android:layout_weight="1">
+
+                        <CheckBox
+                            android:text="@string/btn_crypto_sign"
+                            android:id="@+id/cb_crypto_signature"
+                            android:layout_gravity="center_vertical"
+                            android:layout_width="wrap_content"
+                            android:layout_height="wrap_content"/>
+
+                        <LinearLayout
+                            android:orientation="vertical"
+                            android:layout_gravity="center_vertical"
+                            android:layout_height="wrap_content"
+                            android:layout_width="wrap_content"
+                            android:paddingRight="2dip">
+
+                            <TextView
+                                android:id="@+id/userId"
+                                android:text=""
+                                android:ellipsize="end"
+                                android:textAppearance="?android:attr/textAppearanceSmall"
+                                android:layout_width="wrap_content"
+                                android:layout_height="wrap_content"/>
+
+                            <TextView
+                                android:id="@+id/userIdRest"
+                                android:text=""
+                                android:textSize="10sp"
+                                android:ellipsize="end"
+                                android:layout_width="wrap_content"
+                                android:layout_height="wrap_content"/>
+
+                        </LinearLayout>
+
+                    </LinearLayout>
+
+                    <CheckBox
+                        android:text="@string/btn_encrypt"
+                        android:id="@+id/cb_encrypt"
+                        android:layout_gravity="center_vertical"
+                        android:layout_width="0dip"
+                        android:layout_height="wrap_content"
+                        android:layout_weight="1"/>
+
+                </LinearLayout>
+
                 <EditText
                     android:id="@+id/subject"
                     android:layout_width="fill_parent"
@@ -77,7 +137,7 @@
                     android:layout_marginLeft="6dip"
                     android:layout_marginRight="6dip"
                     android:hint="@string/message_compose_subject_hint"
-                    android:inputType="textEmailSubject|textAutoCorrect|textCapSentences|textImeMultiLine" 
+                    android:inputType="textEmailSubject|textAutoCorrect|textCapSentences|textImeMultiLine"
                     android:imeOptions="actionNext"
                     android:singleLine="true"
                     android:textColor="@android:color/primary_text_light"
@@ -106,10 +166,10 @@
                 android:layout_height="wrap_content"
                 android:layout_weight="1.0"
                 android:gravity="left|top"
-                android:hint="@string/message_compose_content_hint" 
+                android:hint="@string/message_compose_content_hint"
                 android:inputType="textMultiLine|textAutoCorrect|textCapSentences"
                 android:imeOptions="actionDone|flagNoEnterAction"
-                android:minLines="3"                
+                android:minLines="3"
                 android:textColor="@android:color/primary_text_light"
                 android:textAppearance="?android:attr/textAppearanceMedium" />
 

res/layout/message_view_header.xml

@@ -17,7 +17,7 @@
             android:layout_height="wrap_content"
             android:orientation="vertical"
             >
-        <LinearLayout 
+        <LinearLayout
           android:layout_width="fill_parent"
           android:layout_alignParentRight="true"
           android:layout_alignParentTop="true"
@@ -27,7 +27,7 @@
             android:layout_width="fill_parent"
             android:layout_height="wrap_content"
             android:paddingLeft="4dip"
-            android:layout_weight="5" 
+            android:layout_weight="5"
             android:orientation="vertical">
          <TextView android:id="@+id/subject"
             android:layout_width="fill_parent"
@@ -112,7 +112,7 @@
           </LinearLayout>
           <LinearLayout android:id="@+id/topright_container"
                 android:orientation="vertical"
-                android:layout_weight="0.1" 
+                android:layout_weight="0.1"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:gravity="right"
@@ -179,6 +179,73 @@
             android:layout_height="wrap_content"
             android:text="@string/message_view_show_pictures_action" />
     </LinearLayout>
+    <LinearLayout
+        android:id="@+id/layout_decrypt"
+        android:orientation="horizontal"
+        android:layout_width="fill_parent"
+        android:layout_height="wrap_content"
+        android:visibility="gone">
+
+        <LinearLayout
+            android:id="@+id/crypto_signature"
+            android:orientation="horizontal"
+            android:layout_height="wrap_content"
+            android:layout_width="0dip"
+            android:layout_weight="2"
+            android:gravity="center_vertical">
+
+            <RelativeLayout
+                android:layout_height="wrap_content"
+                android:layout_width="wrap_content">
+
+                <ImageView
+                    android:id="@+id/ic_crypto_signature"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:src="@drawable/signed_large"/>
+
+                <ImageView
+                    android:id="@+id/ic_crypto_signature_status"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:src="@drawable/overlay_error"/>
+
+            </RelativeLayout>
+
+            <LinearLayout
+                android:orientation="vertical"
+                android:layout_height="wrap_content"
+                android:layout_width="wrap_content"
+                android:paddingLeft="5dip">
+
+                <TextView
+                    android:id="@+id/userId"
+                    android:textAppearance="?android:attr/textAppearanceMedium"
+                    android:ellipsize="end"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:layout_gravity="left"/>
+
+                <TextView
+                    android:id="@+id/userIdRest"
+                    android:textAppearance="?android:attr/textAppearanceSmall"
+                    android:ellipsize="end"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:layout_gravity="left"/>
+
+            </LinearLayout>
+
+        </LinearLayout>
+
+        <Button
+            android:text="@string/btn_decrypt"
+            android:id="@+id/btn_decrypt"
+            android:layout_width="0dip"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"/>
+
+    </LinearLayout>
     <!-- Content area -->
     <WebView
         android:id="@+id/message_content"

res/values-ja/strings.xml

@@ -470,7 +470,6 @@ K-9 Mail セットアップにようこそ。\nK-9 はオープンソースで
     <string name="account_setup_options_mail_display_count_500">５００件</string>
     <string name="account_setup_options_mail_display_count_1000">１０００件</string>
 
-
     <string name="move_copy_cannot_copy_unsynced_message">サーバーと同期されていないメールをコピーまたは移動できません</string>
 
     <string name="account_setup_failed_dlg_title">設定エラー</string>
@@ -886,7 +885,6 @@ K-9 Mail セットアップにようこそ。\nK-9 はオープンソースで
 
     <string name="save_or_discard_draft_message_dlg_title">メッセージの下書き保存</string>
     <string name="save_or_discard_draft_message_instructions_fmt">メッセージを保存しますか？</string>
-
     <string name="charset_not_found">このメッセージに使われている文字セット \"<xliff:g id="charset">%s</xliff:g>\" は存在していません</string>
 
     <string name="select_text_now">選択したテキストをコピーします</string>

res/values/arrays.xml

@@ -589,4 +589,14 @@
         <item>5</item>
     </string-array>
 
+    <string-array name="account_settings_crypto_app_entries">
+        <item>@string/account_settings_crypto_app_none</item>
+        <item>APG</item>
+    </string-array>
+
+    <string-array name="account_settings_crypto_app_values">
+        <item></item>
+        <item>apg</item>
+    </string-array>
+
 </resources>

res/values/strings.xml

@@ -512,6 +512,12 @@ Welcome to K-9 Mail setup.  K-9 is an open source mail client for Android origin
     <string name="account_settings_message_lists">Listing messages</string>
     <string name="account_settings_message_view">Viewing messages</string>
     <string name="account_settings_quote_prefix_label">Quote prefix</string>
+    <string name="account_settings_crypto">Cryptography</string>
+    <string name="account_settings_crypto_app">OpenPGP Provider</string>
+    <string name="account_settings_crypto_app_none">None</string>
+    <string name="account_settings_crypto_app_not_available">not available</string>
+    <string name="account_settings_crypto_auto_signature">Auto-sign</string>
+    <string name="account_settings_crypto_auto_signature_summary">Use the account\'s email address to guess the signature key.</string>
 
     <string name="account_settings_mail_check_frequency_label">Folder poll check frequency</string>
     <string name="account_settings_second_class_check_frequency_label">2nd class check frequency</string>
@@ -891,6 +897,20 @@ Welcome to K-9 Mail setup.  K-9 is an open source mail client for Android origin
     <string name="misc_preferences_attachment_title">Use Gallery bug work-around</string>
     <string name="misc_preferences_attachment_description">Show buttons to add image/video attachments (to work around a Gallery 3D bug)</string>
 
+    <!-- APG related -->
+    <string name="error_activity_not_found">No suitable application for this action found.</string>
+    <string name="error_apg_version_not_supported">The installed APG version is not supported.</string>
+    <string name="btn_crypto_sign">Sign</string>
+    <string name="btn_encrypt">Encrypt</string>
+    <string name="btn_decrypt">Decrypt</string>
+    <string name="btn_verify">Verify</string>
+    <string name="unknown_crypto_signature_user_id">&lt;unknown&gt;</string>
+    <string name="key_id">id: %s</string>
+    <string name="insufficient_apg_permissions">K-9 doesn\'t have permission to access APG fully, please reinstall K-9 to fix that.</string>
+    <string name="pgp_mime_unsupported">PGP/MIME messages are not supported yet.</string>
+    <string name="attachment_encryption_unsupported">Warning: attachments are NOT signed or encrypted yet.</string>
+    <string name="send_aborted">Send aborted.</string>
+
     <string name="save_or_discard_draft_message_dlg_title">Save draft message?</string>
     <string name="save_or_discard_draft_message_instructions_fmt">Save or Discard this message?</string>
 

res/xml/account_settings_preferences.xml

@@ -207,6 +207,22 @@
 
     </PreferenceCategory>
 
+    <PreferenceCategory android:title="@string/account_settings_crypto">
+
+        <ListPreference
+            android:key="crypto_app"
+            android:title="@string/account_settings_crypto_app"
+            android:entries="@array/account_settings_crypto_app_entries"
+            android:entryValues="@array/account_settings_crypto_app_values"
+            android:dialogTitle="@string/account_settings_crypto_app" />
+
+        <CheckBoxPreference
+            android:key="crypto_auto_signature"
+            android:title="@string/account_settings_crypto_auto_signature"
+            android:summary="@string/account_settings_crypto_auto_signature_summary"
+            android:dependency="crypto_app"/>
+    </PreferenceCategory>
+
     <PreferenceCategory android:title="@string/account_settings_notifications">
 
         <CheckBoxPreference

src/com/fsck/k9/Account.java

@@ -107,6 +107,8 @@ public class Account implements BaseAccount
     private boolean mRingNotified;
     private String mQuotePrefix;
     private boolean mSyncRemoteDeletions;
+    private String mCryptoApp;
+    private boolean mCryptoAutoSignature;
 
     /**
      * Name of the folder that was last selected for a copy or move operation.
@@ -171,6 +173,8 @@ public class Account implements BaseAccount
         maximumAutoDownloadMessageSize = 32768;
         mQuotePrefix = DEFAULT_QUOTE_PREFIX;
         mSyncRemoteDeletions = true;
+        mCryptoApp = "";
+        mCryptoAutoSignature = false;
 
         searchableFolders = Searchable.ALL;
 
@@ -270,14 +274,12 @@ public class Account implements BaseAccount
                                   (random.nextInt(0x70) * 0xff) +
                                   (random.nextInt(0x70) * 0xffff) +
                                   0xff000000);
-
         mLedColor = prefs.getInt(mUuid+".ledColor", mChipColor);
 
         mVibrate = prefs.getBoolean(mUuid + ".vibrate", false);
         mVibratePattern = prefs.getInt(mUuid + ".vibratePattern", 0);
         mVibrateTimes = prefs.getInt(mUuid + ".vibrateTimes", 5);
 
-
         mRing = prefs.getBoolean(mUuid + ".ring", true);
 
         try
@@ -356,6 +358,9 @@ public class Account implements BaseAccount
 
         mIsSignatureBeforeQuotedText = prefs.getBoolean(mUuid  + ".signatureBeforeQuotedText", false);
         identities = loadIdentities(prefs);
+
+        mCryptoApp = prefs.getString(mUuid + ".cryptoApp", "");
+        mCryptoAutoSignature = prefs.getBoolean(mUuid + ".cryptoAutoSignature", false);
     }
 
 
@@ -518,6 +523,8 @@ public class Account implements BaseAccount
         editor.putInt(mUuid + ".maximumPolledMessageAge", maximumPolledMessageAge);
         editor.putInt(mUuid + ".maximumAutoDownloadMessageSize", maximumAutoDownloadMessageSize);
         editor.putString(mUuid + ".quotePrefix", mQuotePrefix);
+        editor.putString(mUuid + ".cryptoApp", mCryptoApp);
+        editor.putBoolean(mUuid + ".cryptoAutoSignature", mCryptoAutoSignature);
 
         for (String type : networkTypes)
         {
@@ -1411,6 +1418,25 @@ public class Account implements BaseAccount
         mEnableMoveButtons = enableMoveButtons;
     }
 
+    public String getCryptoApp()
+    {
+        return mCryptoApp;
+    }
+
+    public void setCryptoApp(String cryptoApp)
+    {
+        mCryptoApp = cryptoApp;
+    }
+
+    public boolean getCryptoAutoSignature()
+    {
+        return mCryptoAutoSignature;
+    }
+
+    public void setCryptoAutoSignature(boolean cryptoAutoSignature)
+    {
+        mCryptoAutoSignature = cryptoAutoSignature;
+    }
     public synchronized boolean syncRemoteDeletions()
     {
         return mSyncRemoteDeletions;

src/com/fsck/k9/activity/MessageCompose.java

@@ -1,6 +1,16 @@
 
 package com.fsck.k9.activity;
 
+import java.io.File;
+import java.io.Serializable;
+import java.io.UnsupportedEncodingException;
+import java.net.URLDecoder;
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.List;
+import java.util.StringTokenizer;
+
+import org.apache.james.mime4j.codec.EncoderUtil;
 import android.app.AlertDialog;
 import android.app.Dialog;
 import android.content.ContentResolver;
@@ -26,25 +36,42 @@ import android.view.View.OnClickListener;
 import android.view.View.OnFocusChangeListener;
 import android.view.Window;
 import android.widget.AutoCompleteTextView.Validator;
-import android.widget.*;
+import android.widget.Button;
-import com.fsck.k9.*;
+import android.widget.CheckBox;
+import android.widget.EditText;
+import android.widget.ImageButton;
+import android.widget.LinearLayout;
+import android.widget.MultiAutoCompleteTextView;
+import android.widget.TextView;
+import android.widget.Toast;
+
+import com.fsck.k9.Account;
+import com.fsck.k9.EmailAddressAdapter;
+import com.fsck.k9.EmailAddressValidator;
+import com.fsck.k9.Identity;
+import com.fsck.k9.K9;
+import com.fsck.k9.Preferences;
+import com.fsck.k9.R;
 import com.fsck.k9.controller.MessagingController;
 import com.fsck.k9.controller.MessagingListener;
+import com.fsck.k9.crypto.CryptoProvider;
 import com.fsck.k9.helper.Utility;
-import com.fsck.k9.mail.*;
+import com.fsck.k9.mail.Address;
+import com.fsck.k9.mail.Body;
+import com.fsck.k9.mail.Flag;
+import com.fsck.k9.mail.Message;
 import com.fsck.k9.mail.Message.RecipientType;
-import com.fsck.k9.mail.internet.*;
+import com.fsck.k9.mail.MessagingException;
+import com.fsck.k9.mail.Multipart;
+import com.fsck.k9.mail.Part;
+import com.fsck.k9.mail.internet.MimeBodyPart;
+import com.fsck.k9.mail.internet.MimeHeader;
+import com.fsck.k9.mail.internet.MimeMessage;
+import com.fsck.k9.mail.internet.MimeMultipart;
+import com.fsck.k9.mail.internet.MimeUtility;
+import com.fsck.k9.mail.internet.TextBody;
 import com.fsck.k9.mail.store.LocalStore;
 import com.fsck.k9.mail.store.LocalStore.LocalAttachmentBody;
-import java.io.File;
-import java.io.Serializable;
-import java.io.UnsupportedEncodingException;
-import java.net.URLDecoder;
-import java.util.ArrayList;
-import java.util.Date;
-import java.util.List;
-import java.util.StringTokenizer;
-import org.apache.james.mime4j.codec.EncoderUtil;
 
 public class MessageCompose extends K9Activity implements OnClickListener, OnFocusChangeListener
 {
@@ -55,8 +82,8 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
     private static final String ACTION_FORWARD = "com.fsck.k9.intent.action.FORWARD";
     private static final String ACTION_EDIT_DRAFT = "com.fsck.k9.intent.action.EDIT_DRAFT";
 
-
     private static final String EXTRA_ACCOUNT = "account";
+    private static final String EXTRA_MESSAGE_BODY  = "messageBody";
     private static final String EXTRA_MESSAGE_REFERENCE = "message_reference";
 
     private static final String STATE_KEY_ATTACHMENTS =
@@ -75,6 +102,7 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
         "com.fsck.k9.activity.MessageCompose.identityChanged";
     private static final String STATE_IDENTITY =
         "com.fsck.k9.activity.MessageCompose.identity";
+    private static final String STATE_CRYPTO = "crypto";
     private static final String STATE_IN_REPLY_TO = "com.fsck.k9.activity.MessageCompose.inReplyTo";
     private static final String STATE_REFERENCES = "com.fsck.k9.activity.MessageCompose.references";
 
@@ -110,6 +138,7 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
     private MessageReference mMessageReference;
 
     private Message mSourceMessage;
+    private String mSourceMessageBody;
 
     /**
      * Indicates that the source message has been processed at least once and should not
@@ -130,11 +159,19 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
     private View mQuotedTextBar;
     private ImageButton mQuotedTextDelete;
     private EditText mQuotedText;
+    private View mEncryptLayout;
+    private CheckBox mCryptoSignatureCheckbox;
+    private CheckBox mEncryptCheckbox;
+    private TextView mCryptoSignatureUserId;
+    private TextView mCryptoSignatureUserIdRest;
+
+    private CryptoProvider mCrypto = null;
 
     private String mReferences;
     private String mInReplyTo;
 
     private boolean mDraftNeedsSaving = false;
+    private boolean mPreventDraftSaving = false;
 
     /**
      * The draft uid of this message. This is used when saving drafts so that the same draft is
@@ -220,14 +257,17 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
      * @param account
      * @param message
      * @param replyAll
+     * @param messageBody optional, for decrypted messages, null if it should be grabbed from the given message
      */
     public static void actionReply(
         Context context,
         Account account,
         Message message,
-        boolean replyAll)
+        boolean replyAll,
+        String messageBody)
     {
         Intent i = new Intent(context, MessageCompose.class);
+        i.putExtra(EXTRA_MESSAGE_BODY, messageBody);
         i.putExtra(EXTRA_MESSAGE_REFERENCE, message.makeMessageReference());
         if (replyAll)
         {
@@ -245,10 +285,16 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
      * @param context
      * @param account
      * @param message
+     * @param messageBody optional, for decrypted messages, null if it should be grabbed from the given message
      */
-    public static void actionForward(Context context, Account account, Message message)
+    public static void actionForward(
+        Context context,
+        Account account,
+        Message message,
+        String messageBody)
     {
         Intent i = new Intent(context, MessageCompose.class);
+        i.putExtra(EXTRA_MESSAGE_BODY, messageBody);
         i.putExtra(EXTRA_MESSAGE_REFERENCE, message.makeMessageReference());
         i.setAction(ACTION_FORWARD);
         context.startActivity(i);
@@ -282,6 +328,7 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
         final Intent intent = getIntent();
 
         mMessageReference = (MessageReference) intent.getSerializableExtra(EXTRA_MESSAGE_REFERENCE);
+        mSourceMessageBody = (String) intent.getStringExtra(EXTRA_MESSAGE_BODY);
 
         final String accountUuid = (mMessageReference != null) ?
                                    mMessageReference.accountUuid :
@@ -613,9 +660,113 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
             mMessageContentView.requestFocus();
         }
 
+        mEncryptLayout = (View)findViewById(R.id.layout_encrypt);
+        mCryptoSignatureCheckbox = (CheckBox)findViewById(R.id.cb_crypto_signature);
+        mCryptoSignatureUserId = (TextView)findViewById(R.id.userId);
+        mCryptoSignatureUserIdRest = (TextView)findViewById(R.id.userIdRest);
+        mEncryptCheckbox = (CheckBox)findViewById(R.id.cb_encrypt);
+
+        initializeCrypto();
+        if (mCrypto.isAvailable(this))
+        {
+            mEncryptLayout.setVisibility(View.VISIBLE);
+            mCryptoSignatureCheckbox.setOnClickListener(new OnClickListener()
+            {
+                @Override
+                public void onClick(View v)
+                {
+                    CheckBox checkBox = (CheckBox) v;
+                    if (checkBox.isChecked())
+                    {
+                        mPreventDraftSaving = true;
+                        if (!mCrypto.selectSecretKey(MessageCompose.this))
+                        {
+                            mPreventDraftSaving = false;
+                        }
+                        checkBox.setChecked(false);
+                    }
+                    else
+                    {
+                        mCrypto.setSignatureKeyId(0);
+                        updateEncryptLayout();
+                    }
+                }
+            });
+
+            if (mAccount.getCryptoAutoSignature())
+            {
+                long ids[] = mCrypto.getSecretKeyIdsFromEmail(this, mIdentity.getEmail());
+                if (ids != null && ids.length > 0)
+                {
+                    mCrypto.setSignatureKeyId(ids[0]);
+                    mCrypto.setSignatureUserId(mCrypto.getUserId(this, ids[0]));
+                }
+                else
+                {
+                    mCrypto.setSignatureKeyId(0);
+                    mCrypto.setSignatureUserId(null);
+                }
+            }
+            updateEncryptLayout();
+        }
+        else
+        {
+            mEncryptLayout.setVisibility(View.GONE);
+        }
+
         mDraftNeedsSaving = false;
     }
 
+    private void initializeCrypto()
+    {
+        if (mCrypto != null)
+        {
+            return;
+        }
+        mCrypto = CryptoProvider.createInstance(mAccount);
+    }
+
+    /**
+     * Fill the encrypt layout with the latest data about signature key and encryption keys.
+     */
+    public void updateEncryptLayout()
+    {
+        if (!mCrypto.hasSignatureKey())
+        {
+            mCryptoSignatureCheckbox.setText(R.string.btn_crypto_sign);
+            mCryptoSignatureCheckbox.setChecked(false);
+            mCryptoSignatureUserId.setVisibility(View.INVISIBLE);
+            mCryptoSignatureUserIdRest.setVisibility(View.INVISIBLE);
+        }
+        else
+        {
+            // if a signature key is selected, then the checkbox itself has no text
+            mCryptoSignatureCheckbox.setText("");
+            mCryptoSignatureCheckbox.setChecked(true);
+            mCryptoSignatureUserId.setVisibility(View.VISIBLE);
+            mCryptoSignatureUserIdRest.setVisibility(View.VISIBLE);
+            mCryptoSignatureUserId.setText(R.string.unknown_crypto_signature_user_id);
+            mCryptoSignatureUserIdRest.setText("");
+
+            String userId = mCrypto.getSignatureUserId();
+            if (userId == null)
+            {
+                userId = mCrypto.getUserId(this, mCrypto.getSignatureKeyId());
+                mCrypto.setSignatureUserId(userId);
+            }
+
+            if (userId != null)
+            {
+                String chunks[] = mCrypto.getSignatureUserId().split(" <", 2);
+                mCryptoSignatureUserId.setText(chunks[0]);
+                if (chunks.length > 1)
+                {
+                    mCryptoSignatureUserIdRest.setText("<" + chunks[1]);
+                }
+            }
+        }
+    }
+
     @Override
     public void onResume()
     {
@@ -659,6 +810,7 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
         outState.putString(STATE_KEY_DRAFT_UID, mDraftUid);
         outState.putSerializable(STATE_IDENTITY, mIdentity);
         outState.putBoolean(STATE_IDENTITY_CHANGED, mIdentityChanged);
+        outState.putSerializable(STATE_CRYPTO, mCrypto);
         outState.putString(STATE_IN_REPLY_TO, mInReplyTo);
         outState.putString(STATE_REFERENCES, mReferences);
     }
@@ -682,10 +834,14 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
         mDraftUid = savedInstanceState.getString(STATE_KEY_DRAFT_UID);
         mIdentity = (Identity)savedInstanceState.getSerializable(STATE_IDENTITY);
         mIdentityChanged = savedInstanceState.getBoolean(STATE_IDENTITY_CHANGED);
+        mCrypto = (CryptoProvider) savedInstanceState.getSerializable(STATE_CRYPTO);
         mInReplyTo = savedInstanceState.getString(STATE_IN_REPLY_TO);
         mReferences = savedInstanceState.getString(STATE_REFERENCES);
+
+        initializeCrypto();
         updateFrom();
         updateSignature();
+        updateEncryptLayout();
 
         mDraftNeedsSaving = false;
     }
@@ -733,6 +889,32 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
         return addresses;
     }
 
+    private String buildText(boolean appendSig)
+    {
+        /*
+         * Build the Body that will contain the text of the message. We'll decide where to
+         * include it later.
+         */
+
+        String text = mMessageContentView.getText().toString();
+        if (appendSig && mAccount.isSignatureBeforeQuotedText())
+        {
+            text = appendSignature(text);
+        }
+
+        if (mQuotedTextBar.getVisibility() == View.VISIBLE)
+        {
+            text += "\n" + mQuotedText.getText().toString();
+        }
+
+        if (appendSig && mAccount.isSignatureBeforeQuotedText() == false)
+        {
+            text = appendSignature(text);
+        }
+
+        return text;
+    }
+
     private MimeMessage createMessage(boolean appendSig) throws MessagingException
     {
         MimeMessage message = new MimeMessage();
@@ -761,27 +943,14 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
             message.setReferences(mReferences);
         }
 
-
+        String text = null;
-        /*
+        if (mCrypto.getEncryptedData() != null)
-         * Build the Body that will contain the text of the message. We'll decide where to
-         * include it later.
-         */
-
-        String text = mMessageContentView.getText().toString();
-        if (appendSig && mAccount.isSignatureBeforeQuotedText())
         {
-            text = appendSignature(text);
+            text = mCrypto.getEncryptedData();
         }
-
+        else
-        if (mQuotedTextBar.getVisibility() == View.VISIBLE)
         {
-            text += "\n" + mQuotedText.getText().toString();
+            text = buildText(appendSig);
-        }
-
-
-        if (appendSig && mAccount.isSignatureBeforeQuotedText() == false)
-        {
-            text = appendSignature(text);
         }
 
         TextBody body = new TextBody(text);
@@ -869,7 +1038,6 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
     }
 
 
-
     private void sendMessage()
     {
         new SendMessageTask().execute();
@@ -881,10 +1049,37 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
 
     private void saveIfNeeded()
     {
-        if (!mDraftNeedsSaving)
+        if (!mDraftNeedsSaving || mPreventDraftSaving || mCrypto.hasEncryptionKeys())
         {
             return;
         }
+
+        mDraftNeedsSaving = false;
+        saveMessage();
+    }
+
+    public void onEncryptionKeySelectionDone()
+    {
+        if (mCrypto.hasEncryptionKeys())
+        {
+            onSend();
+        }
+        else
+        {
+            Toast.makeText(this, R.string.send_aborted, Toast.LENGTH_SHORT).show();
+        }
+    }
+
+    public void onEncryptDone()
+    {
+        if (mCrypto.getEncryptedData() != null)
+        {
+            onSend();
+        }
+        else
+        {
+            Toast.makeText(this, R.string.send_aborted, Toast.LENGTH_SHORT).show();
+        }
         mDraftNeedsSaving = false;
         saveMessage();
     }
@@ -897,6 +1092,51 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
             Toast.makeText(this, getString(R.string.message_compose_error_no_recipients), Toast.LENGTH_LONG).show();
             return;
         }
+        if (mEncryptCheckbox.isChecked() && !mCrypto.hasEncryptionKeys())
+        {
+            // key selection before encryption
+            String emails = "";
+            Address[][] addresses = new Address[][] { getAddresses(mToView),
+                    getAddresses(mCcView),
+                    getAddresses(mBccView)
+                                                    };
+            for (Address[] addressArray : addresses)
+            {
+                for (Address address : addressArray)
+                {
+                    if (emails.length() != 0)
+                    {
+                        emails += ",";
+                    }
+                    emails += address.getAddress();
+                }
+            }
+            if (emails.length() != 0)
+            {
+                emails += ",";
+            }
+            emails += mIdentity.getEmail();
+
+            mPreventDraftSaving = true;
+            if (!mCrypto.selectEncryptionKeys(MessageCompose.this, emails))
+            {
+                mPreventDraftSaving = false;
+            }
+            return;
+        }
+        if (mCrypto.hasEncryptionKeys() || mCrypto.hasSignatureKey())
+        {
+            if (mCrypto.getEncryptedData() == null)
+            {
+                String text = buildText(true);
+                mPreventDraftSaving = true;
+                if (!mCrypto.encrypt(this, text))
+                {
+                    mPreventDraftSaving = false;
+                }
+                return;
+            }
+        }
         sendMessage();
         mDraftNeedsSaving = false;
         finish();
@@ -956,6 +1196,10 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
      */
     private void onAddAttachment2(final String mime_type)
     {
+        if (mCrypto.isAvailable(this))
+        {
+            Toast.makeText(this, R.string.attachment_encryption_unsupported, Toast.LENGTH_LONG).show();
+        }
         Intent i = new Intent(Intent.ACTION_GET_CONTENT);
         i.addCategory(Intent.CATEGORY_OPENABLE);
         i.setType(mime_type);
@@ -1050,6 +1294,14 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
     @Override
     protected void onActivityResult(int requestCode, int resultCode, Intent data)
     {
+        // if a CryptoSystem activity is returning, then mPreventDraftSaving was set to true
+        mPreventDraftSaving = false;
+
+        if (mCrypto.onActivityResult(this, requestCode, resultCode, data))
+        {
+            return;
+        }
+
         if (resultCode != RESULT_OK)
             return;
         if (data == null)
@@ -1059,7 +1311,6 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
         switch (requestCode)
         {
             case ACTIVITY_REQUEST_PICK_ATTACHMENT:
-
                 addAttachment(data.getData());
                 mDraftNeedsSaving = true;
                 break;
@@ -1196,6 +1447,7 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
         switch (item.getItemId())
         {
             case R.id.send:
+                mCrypto.setEncryptionKeys(null);
                 onSend();
                 break;
             case R.id.save:
@@ -1442,7 +1694,7 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
 
                 Part part = MimeUtility.findFirstPartByMimeType(mSourceMessage,
                             "text/plain");
-                if (part != null)
+                if (part != null || mSourceMessageBody != null)
                 {
                     String quotedText = String.format(
                                             getString(R.string.message_compose_reply_header_fmt),
@@ -1452,8 +1704,16 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
                     // "$" and "\" in the quote prefix have to be escaped for
                     // the replaceAll() invocation.
                     final String escapedPrefix = prefix.replaceAll("(\\\\|\\$)", "\\\\$1");
-                    quotedText += MimeUtility.getTextFromPart(part).replaceAll(
+
-                                      "(?m)^", escapedPrefix);
+                    if (mSourceMessageBody != null)
+                    {
+                        quotedText += mSourceMessageBody.replaceAll("(?m)^", escapedPrefix);
+                    }
+                    else
+                    {
+                        quotedText += MimeUtility.getTextFromPart(part).replaceAll(
+                                          "(?m)^", escapedPrefix);
+                    }
 
                     quotedText = quotedText.replaceAll("\\\r", "");
                     mQuotedText.setText(quotedText);
@@ -1548,9 +1808,13 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
                 {
                     part = MimeUtility.findFirstPartByMimeType(message, "text/html");
                 }
-                if (part != null)
+                if (part != null || mSourceMessageBody != null)
                 {
-                    String quotedText = MimeUtility.getTextFromPart(part);
+                    String quotedText = mSourceMessageBody;
+                    if (quotedText == null)
+                    {
+                        quotedText = MimeUtility.getTextFromPart(part);
+                    }
                     if (quotedText != null)
                     {
                         String text = String.format(

src/com/fsck/k9/activity/MessageList.java

@@ -1103,17 +1103,17 @@ public class MessageList
 
     private void onReply(MessageInfoHolder holder)
     {
-        MessageCompose.actionReply(this, holder.message.getFolder().getAccount(), holder.message, false);
+        MessageCompose.actionReply(this, holder.message.getFolder().getAccount(), holder.message, false, null);
     }
 
     private void onReplyAll(MessageInfoHolder holder)
     {
-        MessageCompose.actionReply(this, holder.message.getFolder().getAccount(), holder.message, true);
+        MessageCompose.actionReply(this, holder.message.getFolder().getAccount(), holder.message, true, null);
     }
 
     private void onForward(MessageInfoHolder holder)
     {
-        MessageCompose.actionForward(this, holder.message.getFolder().getAccount(), holder.message);
+        MessageCompose.actionForward(this, holder.message.getFolder().getAccount(), holder.message, null);
     }
 
     private void onMarkAllAsRead(final Account account, final String folder)

src/com/fsck/k9/activity/MessageView.java

@@ -64,6 +64,7 @@ import com.fsck.k9.Preferences;
 import com.fsck.k9.R;
 import com.fsck.k9.controller.MessagingController;
 import com.fsck.k9.controller.MessagingListener;
+import com.fsck.k9.crypto.CryptoProvider;
 import com.fsck.k9.mail.Address;
 import com.fsck.k9.mail.Flag;
 import com.fsck.k9.mail.Message;
@@ -83,6 +84,8 @@ public class MessageView extends K9Activity implements OnClickListener
     private static final String EXTRA_MESSAGE_REFERENCES = "com.fsck.k9.MessageView_messageReferences";
     private static final String EXTRA_NEXT = "com.fsck.k9.MessageView_next";
 
+    private static final String STATE_CRYPTO = "crypto";
+
     private static final int ACTIVITY_CHOOSE_FOLDER_MOVE = 1;
     private static final int ACTIVITY_CHOOSE_FOLDER_COPY = 2;
 
@@ -95,6 +98,12 @@ public class MessageView extends K9Activity implements OnClickListener
     public View chip;
     private CheckBox mFlagged;
     private int defaultSubjectColor;
+    private View mDecryptLayout;
+    private Button mDecryptButton;
+    private LinearLayout mCryptoSignatureLayout = null;
+    private ImageView mCryptoSignatureStatusImage = null;
+    private TextView mCryptoSignatureUserId = null;
+    private TextView mCryptoSignatureUserIdRest = null;
     private WebView mMessageContentView;
     private LinearLayout mHeaderContainer;
     private LinearLayout mAttachments;
@@ -125,17 +134,16 @@ public class MessageView extends K9Activity implements OnClickListener
     private ArrayList<MessageReference> mMessageReferences;
 
     private Message mMessage;
+    private CryptoProvider mCrypto = null;
 
     private static final int PREVIOUS = 1;
     private static final int NEXT = 2;
 
     private int mLastDirection = PREVIOUS;
 
-
     private MessageReference mNextMessage = null;
     private MessageReference mPreviousMessage = null;
 
-
     private Menu optionsMenu = null;
 
     private Listener mListener = new Listener();
@@ -734,6 +742,39 @@ public class MessageView extends K9Activity implements OnClickListener
         mTopView = mToggleScrollView = (ToggleScrollView)findViewById(R.id.top_view);
         mMessageContentView = (WebView)findViewById(R.id.message_content);
 
+        mDecryptLayout = (View)findViewById(R.id.layout_decrypt);
+        mDecryptButton = (Button)findViewById(R.id.btn_decrypt);
+        mDecryptButton.setOnClickListener(new OnClickListener()
+        {
+            @Override
+            public void onClick(View v)
+            {
+                try
+                {
+                    String data = null;
+                    Part part = MimeUtility.findFirstPartByMimeType(mMessage, "text/plain");
+                    if (part == null)
+                    {
+                        part = MimeUtility.findFirstPartByMimeType(mMessage, "text/html");
+                    }
+                    if (part != null)
+                    {
+                        data = MimeUtility.getTextFromPart(part);
+                    }
+                    mCrypto.decrypt(MessageView.this, data);
+                }
+                catch (MessagingException me)
+                {
+                    Log.e(K9.LOG_TAG, "Unable to decrypt email.", me);
+                }
+            }
+        });
+        mCryptoSignatureLayout = (LinearLayout) findViewById(R.id.crypto_signature);
+        mCryptoSignatureStatusImage = (ImageView) findViewById(R.id.ic_crypto_signature_status);
+        mCryptoSignatureUserId = (TextView) findViewById(R.id.userId);
+        mCryptoSignatureUserIdRest = (TextView) findViewById(R.id.userIdRest);
+        mCryptoSignatureLayout.setVisibility(View.INVISIBLE);
+
         mAttachments = (LinearLayout)findViewById(R.id.attachments);
         mAttachmentIcon = findViewById(R.id.attachment);
         mShowPicturesSection = findViewById(R.id.show_pictures_section);
@@ -808,14 +849,17 @@ public class MessageView extends K9Activity implements OnClickListener
         Intent intent = getIntent();
         Uri uri = intent.getData();
 
-        if (icicle!=null)
+        if (icicle != null)
         {
             mMessageReference = (MessageReference)icicle.getSerializable(EXTRA_MESSAGE_REFERENCE);
             mMessageReferences = (ArrayList<MessageReference>)icicle.getSerializable(EXTRA_MESSAGE_REFERENCES);
+
+            mCrypto = (CryptoProvider) icicle.getSerializable(STATE_CRYPTO);
+            updateDecryptLayout();
         }
         else
         {
-            if (uri==null)
+            if (uri == null)
             {
                 mMessageReference = (MessageReference)intent.getSerializableExtra(EXTRA_MESSAGE_REFERENCE);
                 mMessageReferences = (ArrayList<MessageReference>)intent.getSerializableExtra(EXTRA_MESSAGE_REFERENCES);
@@ -823,7 +867,7 @@ public class MessageView extends K9Activity implements OnClickListener
             else
             {
                 List<String> segmentList = uri.getPathSegments();
-                if (segmentList.size()==3)
+                if (segmentList.size() == 3)
                 {
                     String accountId = segmentList.get(0);
                     Account[] accounts = Preferences.getPreferences(this).getAccounts();
@@ -859,6 +903,7 @@ public class MessageView extends K9Activity implements OnClickListener
                 }
             }
         }
+
         if (K9.DEBUG)
             Log.d(K9.LOG_TAG, "MessageView got message " + mMessageReference);
 
@@ -953,6 +998,18 @@ public class MessageView extends K9Activity implements OnClickListener
     {
         outState.putSerializable(EXTRA_MESSAGE_REFERENCE, mMessageReference);
         outState.putSerializable(EXTRA_MESSAGE_REFERENCES, mMessageReferences);
+        outState.putSerializable(STATE_CRYPTO, mCrypto);
+    }
+
+    @Override
+    protected void onRestoreInstanceState(Bundle savedInstanceState)
+    {
+        super.onRestoreInstanceState(savedInstanceState);
+
+        mCrypto = (CryptoProvider) savedInstanceState.getSerializable(STATE_CRYPTO);
+        initializeCrypto();
+
+        updateDecryptLayout();
     }
 
     private void displayMessage(MessageReference ref)
@@ -970,6 +1027,9 @@ public class MessageView extends K9Activity implements OnClickListener
         mAttachments.removeAllViews();
         findSurroundingMessagesUid();
 
+        mCrypto = null;
+        initializeCrypto();
+
         setupDisplayMessageButtons();
 
         MessagingController.getInstance(getApplication()).loadMessageForView(
@@ -1251,7 +1311,7 @@ public class MessageView extends K9Activity implements OnClickListener
     {
         if (mMessage != null)
         {
-            MessageCompose.actionReply(this, mAccount, mMessage, false);
+            MessageCompose.actionReply(this, mAccount, mMessage, false, mCrypto.getDecryptedData());
             finish();
         }
     }
@@ -1260,7 +1320,7 @@ public class MessageView extends K9Activity implements OnClickListener
     {
         if (mMessage != null)
         {
-            MessageCompose.actionReply(this, mAccount, mMessage, true);
+            MessageCompose.actionReply(this, mAccount, mMessage, true, mCrypto.getDecryptedData());
             finish();
         }
     }
@@ -1269,7 +1329,7 @@ public class MessageView extends K9Activity implements OnClickListener
     {
         if (mMessage != null)
         {
-            MessageCompose.actionForward(this, mAccount, mMessage);
+            MessageCompose.actionForward(this, mAccount, mMessage, mCrypto.getDecryptedData());
             finish();
         }
     }
@@ -1376,6 +1436,11 @@ public class MessageView extends K9Activity implements OnClickListener
     @Override
     protected void onActivityResult(int requestCode, int resultCode, Intent data)
     {
+        if (mCrypto.onActivityResult(this, requestCode, resultCode, data))
+        {
+            return;
+        }
+
         if (resultCode != RESULT_OK)
             return;
 
@@ -1409,6 +1474,9 @@ public class MessageView extends K9Activity implements OnClickListener
                             break;
                     }
                 }
+                break;
+
+
         }
     }
 
@@ -1966,6 +2034,7 @@ public class MessageView extends K9Activity implements OnClickListener
                     public void run()
                     {
                         mMessageContentView.loadUrl("file:///android_asset/downloading.html");
+                        updateDecryptLayout();
                     }
                 });
             }
@@ -2007,30 +2076,39 @@ public class MessageView extends K9Activity implements OnClickListener
                 mHandler.removeAllAttachments();
 
                 String text;
-                Part part = MimeUtility.findFirstPartByMimeType(mMessage, "text/html");
+                String type = "text/html";
-                if (part == null)
+                if (mCrypto.getDecryptedData() != null)
                 {
-                    part = MimeUtility.findFirstPartByMimeType(mMessage, "text/plain");
+                    text = mCrypto.getDecryptedData();
+                    type = "text/plain";
+                }
+                else
+                {
+                    Part part = MimeUtility.findFirstPartByMimeType(mMessage, "text/html");
                     if (part == null)
                     {
-                        text = null;
+                        part = MimeUtility.findFirstPartByMimeType(mMessage, "text/plain");
-                    }
+                        if (part == null)
-                    else
-                    {
-                        LocalTextBody body = (LocalTextBody)part.getBody();
-                        if (body == null)
                         {
                             text = null;
                         }
                         else
                         {
-                            text = body.getBodyForDisplay();
+                            LocalTextBody body = (LocalTextBody)part.getBody();
+                            if (body == null)
+                            {
+                                text = null;
+                            }
+                            else
+                            {
+                                text = body.getBodyForDisplay();
+                            }
                         }
                     }
-                }
+                    else
-                else
+                    {
-                {
+                        text = MimeUtility.getTextFromPart(part);
-                    text = MimeUtility.getTextFromPart(part);
+                    }
                 }
 
                 if (text != null)
@@ -2040,11 +2118,13 @@ public class MessageView extends K9Activity implements OnClickListener
                      * get background images and a million other things that HTML allows.
                      */
                     final String emailText = text;
+                    final String mimeType = type;
                     mHandler.post(new Runnable()
                     {
                         public void run()
                         {
-                            mMessageContentView.loadDataWithBaseURL("http://", emailText, "text/html", "utf-8", null);
+                            mMessageContentView.loadDataWithBaseURL("http://", emailText, mimeType, "utf-8", null);
+                            updateDecryptLayout();
                         }
                     });
                     mHandler.showShowPictures(text.contains("<img"));
@@ -2056,6 +2136,7 @@ public class MessageView extends K9Activity implements OnClickListener
                         public void run()
                         {
                             mMessageContentView.loadUrl("file:///android_asset/empty.html");
+                            updateDecryptLayout();
                         }
                     });
                 }
@@ -2099,6 +2180,7 @@ public class MessageView extends K9Activity implements OnClickListener
                             !MessageView.this.mMessage.isSet(Flag.X_DOWNLOADED_PARTIAL))
                     {
                         mMessageContentView.loadUrl("file:///android_asset/empty.html");
+                        updateDecryptLayout();
                     }
                 }
             });
@@ -2137,6 +2219,7 @@ public class MessageView extends K9Activity implements OnClickListener
                 public void run()
                 {
                     mMessageContentView.loadUrl("file:///android_asset/loading.html");
+                    updateDecryptLayout();
                     setProgressBarIndeterminateVisibility(true);
                 }
             });
@@ -2293,7 +2376,118 @@ public class MessageView extends K9Activity implements OnClickListener
         return slide;
     }
 
+    private void initializeCrypto()
+    {
+        if (mCrypto != null)
+        {
+            return;
+        }
+        if (mAccount == null)
+        {
+            mAccount = Preferences.getPreferences(this).getAccount(mMessageReference.accountUuid);
+        }
+        mCrypto = CryptoProvider.createInstance(mAccount);
+    }
+
     /**
+     * Fill the decrypt layout with signature data, if known, make controls visible, if
+     * they should be visible.
+     */
+    public void updateDecryptLayout()
+    {
+        if (mCrypto.getSignatureKeyId() != 0)
+        {
+            mCryptoSignatureUserIdRest.setText(
+                    getString(R.string.key_id, Long.toHexString(mCrypto.getSignatureKeyId() & 0xffffffffL)));
+            String userId = mCrypto.getSignatureUserId();
+            if (userId == null)
+            {
+                userId = getString(R.string.unknown_crypto_signature_user_id);
+            }
+            String chunks[] = userId.split(" <", 2);
+            String name = chunks[0];
+            if (chunks.length > 1)
+            {
+                mCryptoSignatureUserIdRest.setText("<" + chunks[1]);
+            }
+            mCryptoSignatureUserId.setText(name);
+
+            if (mCrypto.getSignatureSuccess())
+            {
+                mCryptoSignatureStatusImage.setImageResource(R.drawable.overlay_ok);
+            }
+            else if (mCrypto.getSignatureUnknown())
+            {
+                mCryptoSignatureStatusImage.setImageResource(R.drawable.overlay_error);
+            }
+            else
+            {
+                mCryptoSignatureStatusImage.setImageResource(R.drawable.overlay_error);
+            }
+            mCryptoSignatureLayout.setVisibility(View.VISIBLE);
+            mDecryptLayout.setVisibility(View.VISIBLE);
+        }
+
+        if (!true || ((mMessage == null) && (mCrypto.getDecryptedData() == null)))
+        {
+            mDecryptLayout.setVisibility(View.GONE);
+            return;
+        }
+
+        if (mCrypto.getDecryptedData() != null)
+        {
+            if (mCrypto.getSignatureKeyId() == 0)
+            {
+                mDecryptLayout.setVisibility(View.GONE);
+            }
+            else
+            {
+                // no need to show this after decryption/verification
+                mDecryptButton.setVisibility(View.GONE);
+            }
+            return;
+        }
+
+        mDecryptButton.setVisibility(View.VISIBLE);
+
+        if (mCrypto.isEncrypted(mMessage))
+        {
+            mDecryptButton.setText(R.string.btn_decrypt);
+            mDecryptLayout.setVisibility(View.VISIBLE);
+        }
+        else if (mCrypto.isSigned(mMessage))
+        {
+            mDecryptButton.setText(R.string.btn_verify);
+            mDecryptLayout.setVisibility(View.VISIBLE);
+        }
+        else
+        {
+            mDecryptLayout.setVisibility(View.GONE);
+            try
+            {
+                // check for PGP/MIME encryption
+                Part pgp = MimeUtility.findFirstPartByMimeType(mMessage, "application/pgp-encrypted");
+                if (pgp != null)
+                {
+                    Toast.makeText(this, R.string.pgp_mime_unsupported, Toast.LENGTH_LONG).show();
+                }
+            }
+            catch (MessagingException e)
+            {
+                // nothing to do...
+            }
+        }
+    }
+
+    public void onDecryptDone()
+    {
+        // TODO: this might not be enough if the orientation was changed while in APG,
+        // sometimes shows the original encrypted content
+        mMessageContentView.loadDataWithBaseURL("email://", mCrypto.getDecryptedData(), "text/plain", "utf-8", null);
+        updateDecryptLayout();
+    }
+
+    /*
      * Emulate the shift key being pressed to trigger the text selection mode
      * of a WebView.
      */

src/com/fsck/k9/activity/setup/AccountSettings.java

@@ -5,16 +5,25 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.SharedPreferences;
 import android.os.Bundle;
-import android.preference.*;
+import android.preference.CheckBoxPreference;
+import android.preference.EditTextPreference;
+import android.preference.ListPreference;
+import android.preference.Preference;
+import android.preference.RingtonePreference;
 import android.util.Log;
 import android.view.KeyEvent;
-import com.fsck.k9.*;
+
+import com.fsck.k9.Account;
 import com.fsck.k9.Account.FolderMode;
+import com.fsck.k9.K9;
+import com.fsck.k9.Preferences;
+import com.fsck.k9.R;
 import com.fsck.k9.activity.ChooseFolder;
 import com.fsck.k9.activity.ChooseIdentity;
 import com.fsck.k9.activity.ColorPickerDialog;
 import com.fsck.k9.activity.K9PreferenceActivity;
 import com.fsck.k9.activity.ManageIdentities;
+import com.fsck.k9.crypto.Apg;
 import com.fsck.k9.mail.Store;
 import com.fsck.k9.service.MailService;
 
@@ -60,7 +69,8 @@ public class AccountSettings extends K9PreferenceActivity
     private static final String PREFERENCE_MESSAGE_SIZE = "account_autodownload_size";
     private static final String PREFERENCE_QUOTE_PREFIX = "account_quote_prefix";
     private static final String PREFERENCE_SYNC_REMOTE_DELETIONS = "account_sync_remote_deletetions";
-
+    private static final String PREFERENCE_CRYPTO_APP = "crypto_app";
+    private static final String PREFERENCE_CRYPTO_AUTO_SIGNATURE = "crypto_auto_signature";
 
     private Account mAccount;
 
@@ -94,7 +104,8 @@ public class AccountSettings extends K9PreferenceActivity
     private CheckBoxPreference mNotificationOpensUnread;
     private EditTextPreference mAccountQuotePrefix;
     private CheckBoxPreference mSyncRemoteDeletions;
-
+    private ListPreference mCryptoApp;
+    private CheckBoxPreference mCryptoAutoSignature;
 
     public static void actionSettings(Context context, Account account)
     {
@@ -510,6 +521,53 @@ public class AccountSettings extends K9PreferenceActivity
                 return true;
             }
         });
+
+        mCryptoApp = (ListPreference) findPreference(PREFERENCE_CRYPTO_APP);
+        CharSequence cryptoAppEntries[] = mCryptoApp.getEntries();
+        if (!new Apg().isAvailable(this))
+        {
+            int apgIndex = mCryptoApp.findIndexOfValue(Apg.NAME);
+            if (apgIndex >= 0)
+            {
+                cryptoAppEntries[apgIndex] = "APG (" + getResources().getString(R.string.account_settings_crypto_app_not_available) + ")";
+                mCryptoApp.setEntries(cryptoAppEntries);
+            }
+        }
+        mCryptoApp.setValue(String.valueOf(mAccount.getCryptoApp()));
+        mCryptoApp.setSummary(mCryptoApp.getEntry());
+        mCryptoApp.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener()
+        {
+            public boolean onPreferenceChange(Preference preference, Object newValue)
+            {
+                String value = newValue.toString();
+                int index = mCryptoApp.findIndexOfValue(value);
+                mCryptoApp.setSummary(mCryptoApp.getEntries()[index]);
+                mCryptoApp.setValue(value);
+                handleCryptoAppDependencies();
+                if (Apg.NAME.equals(value))
+                {
+                    Apg.createInstance(null).test(AccountSettings.this);
+                }
+                return false;
+            }
+        });
+
+        mCryptoAutoSignature = (CheckBoxPreference) findPreference(PREFERENCE_CRYPTO_AUTO_SIGNATURE);
+        mCryptoAutoSignature.setChecked(mAccount.getCryptoAutoSignature());
+
+        handleCryptoAppDependencies();
+    }
+
+    private void handleCryptoAppDependencies()
+    {
+        if ("".equals(mCryptoApp.getValue()))
+        {
+            mCryptoAutoSignature.setEnabled(false);
+        }
+        else
+        {
+            mCryptoAutoSignature.setEnabled(true);
+        }
     }
 
     @Override
@@ -543,6 +601,8 @@ public class AccountSettings extends K9PreferenceActivity
         mAccount.setSyncRemoteDeletions(mSyncRemoteDeletions.isChecked());
         mAccount.setSearchableFolders(Account.Searchable.valueOf(mSearchableFolders.getValue()));
         mAccount.setQuotePrefix(mAccountQuotePrefix.getText());
+        mAccount.setCryptoApp(mCryptoApp.getValue());
+        mAccount.setCryptoAutoSignature(mCryptoAutoSignature.isChecked());
 
         boolean needsRefresh = mAccount.setAutomaticCheckIntervalMinutes(Integer.parseInt(mCheckFrequency.getValue()));
         needsRefresh |= mAccount.setFolderSyncMode(Account.FolderMode.valueOf(mSyncMode.getValue()));

src/com/fsck/k9/crypto/Apg.java

@@ -0,0 +1,556 @@
+package com.fsck.k9.crypto;
+
+import java.util.Vector;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import android.app.Activity;
+import android.content.ActivityNotFoundException;
+import android.content.ContentUris;
+import android.content.Context;
+import android.content.pm.PackageInfo;
+import android.content.pm.PackageManager.NameNotFoundException;
+import android.database.Cursor;
+import android.net.Uri;
+import android.widget.Toast;
+
+import com.fsck.k9.Account;
+import com.fsck.k9.R;
+import com.fsck.k9.activity.MessageCompose;
+import com.fsck.k9.activity.MessageView;
+import com.fsck.k9.mail.Message;
+import com.fsck.k9.mail.MessagingException;
+import com.fsck.k9.mail.Part;
+import com.fsck.k9.mail.internet.MimeUtility;
+
+public class Apg extends CryptoProvider
+{
+    static final long serialVersionUID = 0x21071235;
+    public static final String NAME = "apg";
+
+    private static final String mApgPackageName = "org.thialfihar.android.apg";
+    private static final int mMinRequiredVersion = 16;
+
+    public static final String AUTHORITY = "org.thialfihar.android.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 = "org.thialfihar.android.apg.intent.DECRYPT";
+        public static final String ENCRYPT = "org.thialfihar.android.apg.intent.ENCRYPT";
+        public static final String DECRYPT_FILE = "org.thialfihar.android.apg.intent.DECRYPT_FILE";
+        public static final String ENCRYPT_FILE = "org.thialfihar.android.apg.intent.ENCRYPT_FILE";
+        public static final String DECRYPT_AND_RETURN = "org.thialfihar.android.apg.intent.DECRYPT_AND_RETURN";
+        public static final String ENCRYPT_AND_RETURN = "org.thialfihar.android.apg.intent.ENCRYPT_AND_RETURN";
+        public static final String SELECT_PUBLIC_KEYS = "org.thialfihar.android.apg.intent.SELECT_PUBLIC_KEYS";
+        public static final String SELECT_SECRET_KEY = "org.thialfihar.android.apg.intent.SELECT_SECRET_KEY";
+    }
+
+    public static final String EXTRA_TEXT = "text";
+    public static final String EXTRA_DATA = "data";
+    public static final String EXTRA_STATUS = "status";
+    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_REPLY_TO = "replyTo";
+    public static final String EXTRA_SEND_TO = "sendTo";
+    public static final String EXTRA_SUBJECT = "subject";
+    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_PROGRESS = "progress";
+    public static final String EXTRA_MAX = "max";
+    public static final String EXTRA_ACCOUNT = "account";
+
+    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);
+
+    public static Apg createInstance(Account account)
+    {
+        return new Apg();
+    }
+
+    /**
+     * Check whether APG is installed and at a high enough version.
+     *
+     * @param context
+     * @return whether a suitable version of APG was found
+     */
+    @Override
+    public boolean isAvailable(Context context)
+    {
+        try
+        {
+            PackageInfo pi = context.getPackageManager().getPackageInfo(mApgPackageName, 0);
+            if (pi.versionCode >= mMinRequiredVersion)
+            {
+                return true;
+            }
+            else
+            {
+                Toast.makeText(context,
+                               R.string.error_apg_version_not_supported, Toast.LENGTH_SHORT).show();
+            }
+        }
+        catch (NameNotFoundException e)
+        {
+            // not found
+        }
+
+        return false;
+    }
+
+    /**
+     * Select the signature key.
+     *
+     * @param activity
+     * @return success or failure
+     */
+    @Override
+    public boolean selectSecretKey(Activity activity)
+    {
+        android.content.Intent intent = new android.content.Intent(Intent.SELECT_SECRET_KEY);
+        try
+        {
+            activity.startActivityForResult(intent, Apg.SELECT_SECRET_KEY);
+            return true;
+        }
+        catch (ActivityNotFoundException e)
+        {
+            Toast.makeText(activity,
+                           R.string.error_activity_not_found,
+                           Toast.LENGTH_SHORT).show();
+            return false;
+        }
+    }
+
+    /**
+     * Select encryption keys.
+     *
+     * @param activity
+     * @param emails The emails that should be used for preselection.
+     * @return success or failure
+     */
+    @Override
+    public boolean selectEncryptionKeys(Activity activity, String emails)
+    {
+        android.content.Intent intent = new android.content.Intent(Apg.Intent.SELECT_PUBLIC_KEYS);
+        long[] initialKeyIds = null;
+        if (!hasEncryptionKeys())
+        {
+            Vector<Long> keyIds = new Vector<Long>();
+            if (hasSignatureKey())
+            {
+                keyIds.add(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.size() > 0)
+            {
+                initialKeyIds = new long[keyIds.size()];
+                for (int i = 0, size = keyIds.size(); i < size; ++i)
+                {
+                    initialKeyIds[i] = keyIds.get(i);
+                }
+            }
+        }
+        else
+        {
+            initialKeyIds = mEncryptionKeyIds;
+        }
+        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;
+        }
+    }
+
+    /**
+     * Get secret key ids based on a given email.
+     *
+     * @param context
+     * @param email The email in question.
+     * @return key ids
+     */
+    @Override
+    public long[] getSecretKeyIdsFromEmail(Context context, String email)
+    {
+        long ids[] = null;
+        try
+        {
+            Uri contentUri = Uri.withAppendedPath(Apg.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)
+        {
+            Toast.makeText(context,
+                           context.getResources().getString(R.string.insufficient_apg_permissions),
+                           Toast.LENGTH_LONG).show();
+        }
+
+        return ids;
+    }
+
+    /**
+     * Get the user id based on the key id.
+     *
+     * @param context
+     * @param keyId
+     * @return user id
+     */
+    @Override
+    public String getUserId(Context context, long keyId)
+    {
+        String userId = null;
+        try
+        {
+            Uri contentUri = ContentUris.withAppendedId(
+                                     Apg.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)
+        {
+            Toast.makeText(context,
+                           context.getResources().getString(R.string.insufficient_apg_permissions),
+                           Toast.LENGTH_LONG).show();
+        }
+
+        if (userId == null)
+        {
+            userId = context.getString(R.string.unknown_crypto_signature_user_id);
+        }
+        return userId;
+    }
+
+    /**
+     * Handle the activity results that concern us.
+     *
+     * @param activity
+     * @param requestCode
+     * @param resultCode
+     * @param data
+     * @return handled or not
+     */
+    @Override
+    public boolean onActivityResult(Activity activity, int requestCode, int resultCode,
+                                    android.content.Intent data)
+    {
+        switch (requestCode)
+        {
+            case Apg.SELECT_SECRET_KEY:
+                if (resultCode != Activity.RESULT_OK || data == null)
+                {
+                    break;
+                }
+                setSignatureKeyId(data.getLongExtra(Apg.EXTRA_KEY_ID, 0));
+                setSignatureUserId(data.getStringExtra(Apg.EXTRA_USER_ID));
+                ((MessageCompose) activity).updateEncryptLayout();
+                break;
+
+            case Apg.SELECT_PUBLIC_KEYS:
+                if (resultCode != Activity.RESULT_OK || data == null)
+                {
+                    mEncryptionKeyIds = null;
+                    ((MessageCompose) activity).onEncryptionKeySelectionDone();
+                    break;
+                }
+                mEncryptionKeyIds = data.getLongArrayExtra(Apg.EXTRA_SELECTION);
+                ((MessageCompose) activity).onEncryptionKeySelectionDone();
+                break;
+
+            case Apg.ENCRYPT_MESSAGE:
+                if (resultCode != Activity.RESULT_OK || data == null)
+                {
+                    mEncryptedData = null;
+                    ((MessageCompose) activity).onEncryptDone();
+                    break;
+                }
+                mEncryptedData = 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 (mEncryptedData == null) {
+                    mEncryptedData = data.getStringExtra(Apg.EXTRA_DECRYPTED_MESSAGE);
+                }
+                if (mEncryptedData != null)
+                {
+                    ((MessageCompose) activity).onEncryptDone();
+                }
+                break;
+
+            case Apg.DECRYPT_MESSAGE:
+                if (resultCode != Activity.RESULT_OK || data == null)
+                {
+                    break;
+                }
+
+                mSignatureUserId = data.getStringExtra(Apg.EXTRA_SIGNATURE_USER_ID);
+                mSignatureKeyId = data.getLongExtra(Apg.EXTRA_SIGNATURE_KEY_ID, 0);
+                mSignatureSuccess = data.getBooleanExtra(Apg.EXTRA_SIGNATURE_SUCCESS, false);
+                mSignatureUnknown = data.getBooleanExtra(Apg.EXTRA_SIGNATURE_UNKNOWN, false);
+
+                mDecryptedData = data.getStringExtra(Apg.EXTRA_DECRYPTED_MESSAGE);
+                ((MessageView) activity).onDecryptDone();
+
+                break;
+
+            default:
+                return false;
+        }
+
+        return true;
+    }
+
+    /**
+     * Start the encrypt activity.
+     *
+     * @param activity
+     * @param data
+     * @return success or failure
+     */
+    @Override
+    public boolean encrypt(Activity activity, String data)
+    {
+        android.content.Intent intent = new android.content.Intent(Intent.ENCRYPT_AND_RETURN);
+        intent.setType("text/plain");
+        intent.putExtra(Apg.EXTRA_TEXT, data);
+        intent.putExtra(Apg.EXTRA_ENCRYPTION_KEY_IDS, mEncryptionKeyIds);
+        intent.putExtra(Apg.EXTRA_SIGNATURE_KEY_ID, mSignatureKeyId);
+        try
+        {
+            activity.startActivityForResult(intent, Apg.ENCRYPT_MESSAGE);
+            return true;
+        }
+        catch (ActivityNotFoundException e)
+        {
+            Toast.makeText(activity,
+                           R.string.error_activity_not_found,
+                           Toast.LENGTH_SHORT).show();
+            return false;
+        }
+    }
+
+    /**
+     * Start the decrypt activity.
+     *
+     * @param activity
+     * @param data
+     * @return success or failure
+     */
+    @Override
+    public boolean decrypt(Activity activity, String data)
+    {
+        android.content.Intent intent = new android.content.Intent(Apg.Intent.DECRYPT_AND_RETURN);
+        intent.setType("text/plain");
+        if (data == null)
+        {
+            return false;
+        }
+        try
+        {
+            intent.putExtra(EXTRA_TEXT, data);
+            activity.startActivityForResult(intent, Apg.DECRYPT_MESSAGE);
+            return true;
+        }
+        catch (ActivityNotFoundException e)
+        {
+            Toast.makeText(activity,
+                           R.string.error_activity_not_found,
+                           Toast.LENGTH_SHORT).show();
+            return false;
+        }
+    }
+
+    public boolean isEncrypted(Message message)
+    {
+        String data = null;
+        try {
+            Part part = MimeUtility.findFirstPartByMimeType(message, "text/plain");
+            if (part == null)
+            {
+                part = MimeUtility.findFirstPartByMimeType(message, "text/html");
+            }
+            if (part != null)
+            {
+                data = MimeUtility.getTextFromPart(part);
+            }
+        }
+        catch (MessagingException e)
+        {
+            // guess not...
+            // TODO: maybe log this?
+        }
+
+        if (data == null)
+        {
+            return false;
+        }
+
+        Matcher matcher = PGP_MESSAGE.matcher(data);
+        return matcher.matches();
+    }
+
+    public boolean isSigned(Message message)
+    {
+        String data = null;
+        try {
+            Part part = MimeUtility.findFirstPartByMimeType(message, "text/plain");
+            if (part == null)
+            {
+                part = MimeUtility.findFirstPartByMimeType(message, "text/html");
+            }
+            if (part != null)
+            {
+                data = MimeUtility.getTextFromPart(part);
+            }
+        }
+        catch (MessagingException e)
+        {
+            // guess not...
+            // TODO: maybe log this?
+        }
+
+        if (data == null)
+        {
+            return false;
+        }
+
+        Matcher matcher = PGP_SIGNED_MESSAGE.matcher(data);
+        return matcher.matches();
+    }
+
+    /**
+     * Get the name of the provider.
+     *
+     * @return provider name
+     */
+    @Override
+    public String getName()
+    {
+        return NAME;
+    }
+
+    /**
+     * Test the APG installation.
+     *
+     * @return success or failure
+     */
+    public boolean test(Context context)
+    {
+        if (!isAvailable(context))
+        {
+            return false;
+        }
+
+        try
+        {
+            // try out one content provider to check permissions
+            Uri contentUri = ContentUris.withAppendedId(
+                                     Apg.CONTENT_URI_SECRET_KEY_RING_BY_KEY_ID,
+                                     12345);
+            Cursor c = context.getContentResolver().query(contentUri,
+                                                      new String[] { "user_id" },
+                                                      null, null, null);
+            if (c != null)
+            {
+                c.close();
+            }
+        }
+        catch (SecurityException e)
+        {
+            // if there was a problem, then let the user know, this will not stop K9/APG from
+            // working, but some features won't be available, so we can still return "true"
+            Toast.makeText(context,
+                           context.getResources().getString(R.string.insufficient_apg_permissions),
+                           Toast.LENGTH_LONG).show();
+        }
+
+        return true;
+    }
+}

src/com/fsck/k9/crypto/CryptoProvider.java

@@ -0,0 +1,107 @@
+package com.fsck.k9.crypto;
+
+import java.io.Serializable;
+
+import android.app.Activity;
+import android.content.Context;
+import android.content.Intent;
+
+import com.fsck.k9.Account;
+import com.fsck.k9.mail.Message;
+
+abstract public class CryptoProvider implements Serializable
+{
+    static final long serialVersionUID = 0x21071234;
+
+    protected long mEncryptionKeyIds[] = null;
+    protected long mSignatureKeyId = 0;
+    protected String mSignatureUserId = null;
+    protected boolean mSignatureSuccess = false;
+    protected boolean mSignatureUnknown = false;
+    protected String mDecryptedData = null;
+    protected String mEncryptedData = null;
+
+    abstract public boolean isAvailable(Context context);
+    abstract public boolean isEncrypted(Message message);
+    abstract public boolean isSigned(Message message);
+    abstract public boolean onActivityResult(Activity activity, int requestCode, int resultCode,
+            Intent data);
+    abstract public boolean selectSecretKey(Activity activity);
+    abstract public boolean selectEncryptionKeys(Activity activity, String emails);
+    abstract public boolean encrypt(Activity activity, String data);
+    abstract public boolean decrypt(Activity activity, String data);
+    abstract public long[] getSecretKeyIdsFromEmail(Context context, String email);
+    abstract public String getUserId(Context context, long keyId);
+    abstract public String getName();
+    abstract public boolean test(Context context);
+
+    public static CryptoProvider createInstance(Account account)
+    {
+        if (Apg.NAME.equals(account.getCryptoApp()))
+        {
+            return Apg.createInstance(account);
+        }
+
+        return None.createInstance(account);
+    }
+
+    public void setSignatureKeyId(long keyId)
+    {
+        mSignatureKeyId = keyId;
+    }
+
+    public long getSignatureKeyId()
+    {
+        return mSignatureKeyId;
+    }
+
+    public void setEncryptionKeys(long keyIds[])
+    {
+        mEncryptionKeyIds = keyIds;
+    }
+
+    public long[] getEncryptionKeys()
+    {
+        return mEncryptionKeyIds;
+    }
+
+    public boolean hasSignatureKey()
+    {
+        return mSignatureKeyId != 0;
+    }
+
+    public boolean hasEncryptionKeys()
+    {
+        return (mEncryptionKeyIds != null) && (mEncryptionKeyIds.length > 0);
+    }
+
+    public String getEncryptedData()
+    {
+        return mEncryptedData;
+    }
+
+    public String getDecryptedData()
+    {
+        return mDecryptedData;
+    }
+
+    public void setSignatureUserId(String userId)
+    {
+        mSignatureUserId = userId;
+    }
+
+    public String getSignatureUserId()
+    {
+        return mSignatureUserId;
+    }
+
+    public boolean getSignatureSuccess()
+    {
+        return mSignatureSuccess;
+    }
+
+    public boolean getSignatureUnknown()
+    {
+        return mSignatureUnknown;
+    }
+}

src/com/fsck/k9/crypto/None.java

@@ -0,0 +1,89 @@
+package com.fsck.k9.crypto;
+
+import android.app.Activity;
+import android.content.Context;
+
+import com.fsck.k9.Account;
+import com.fsck.k9.mail.Message;
+
+public class None extends CryptoProvider
+{
+    static final long serialVersionUID = 0x21071230;
+    public static final String NAME = "";
+
+    public static None createInstance(Account account)
+    {
+        return new None();
+    }
+
+    @Override
+    public boolean isAvailable(Context context)
+    {
+        return false;
+    }
+
+    @Override
+    public boolean selectSecretKey(Activity activity)
+    {
+        return false;
+    }
+
+    @Override
+    public boolean selectEncryptionKeys(Activity activity, String emails)
+    {
+        return false;
+    }
+
+    @Override
+    public long[] getSecretKeyIdsFromEmail(Context context, String email)
+    {
+        return null;
+    }
+
+    @Override
+    public String getUserId(Context context, long keyId)
+    {
+        return null;
+    }
+
+    @Override
+    public boolean onActivityResult(Activity activity, int requestCode, int resultCode,
+                                    android.content.Intent data)
+    {
+        return false;
+    }
+
+    @Override
+    public boolean encrypt(Activity activity, String data)
+    {
+        return false;
+    }
+
+    @Override
+    public boolean decrypt(Activity activity, String data)
+    {
+        return false;
+    }
+
+    public boolean isEncrypted(Message message)
+    {
+        return false;
+    }
+
+    public boolean isSigned(Message message)
+    {
+        return false;
+    }
+
+    @Override
+    public String getName()
+    {
+        return NAME;
+    }
+
+    @Override
+    public boolean test(Context context)
+    {
+        return true;
+    }
+}