diff --git a/OpenKeychain/src/main/AndroidManifest.xml b/OpenKeychain/src/main/AndroidManifest.xml
index 3be9e0aef..7c604611b 100644
--- a/OpenKeychain/src/main/AndroidManifest.xml
+++ b/OpenKeychain/src/main/AndroidManifest.xml
@@ -877,9 +877,6 @@
             android:name=".remote.CryptoInputParcelCacheService"
             android:exported="false"
             android:process=":remote_api" />
-        <service
-            android:name=".service.KeychainService"
-            android:exported="false" />
 
         <provider
             android:name=".provider.KeychainProvider"
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/keysync/KeyserverSyncWorker.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/keysync/KeyserverSyncWorker.java
index 7b638baf3..c4cbaed5d 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/keysync/KeyserverSyncWorker.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/keysync/KeyserverSyncWorker.java
@@ -1,12 +1,13 @@
 package org.sufficientlysecure.keychain.keysync;
 
 
+import java.util.concurrent.atomic.AtomicBoolean;
+
 import android.app.NotificationManager;
 import android.content.Context;
 import android.support.annotation.NonNull;
 import android.support.v4.app.NotificationCompat;
 import android.support.v4.app.NotificationCompat.Builder;
-import android.support.v4.os.CancellationSignal;
 
 import androidx.work.Worker;
 import org.sufficientlysecure.keychain.Constants.NotificationIds;
@@ -25,7 +26,7 @@ import timber.log.Timber;
 
 
 public class KeyserverSyncWorker extends Worker {
-    private CancellationSignal cancellationSignal = new CancellationSignal();
+    private AtomicBoolean cancellationSignal = new AtomicBoolean(false);
 
     @NonNull
     @Override
@@ -128,6 +129,6 @@ public class KeyserverSyncWorker extends Worker {
     @Override
     public void onStopped() {
         super.onStopped();
-        cancellationSignal.cancel();
+        cancellationSignal.set(true);
     }
 }
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/BackupOperation.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/BackupOperation.java
index eb613c27c..c3d9f917d 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/BackupOperation.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/BackupOperation.java
@@ -27,17 +27,19 @@ import java.text.SimpleDateFormat;
 import java.util.Date;
 import java.util.List;
 import java.util.Locale;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.regex.Pattern;
 
 import android.content.Context;
 import android.net.Uri;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
-import android.support.v4.os.CancellationSignal;
 
 import org.bouncycastle.bcpg.ArmoredOutputStream;
 import org.sufficientlysecure.keychain.Constants;
 import org.sufficientlysecure.keychain.R;
+import org.sufficientlysecure.keychain.daos.KeyRepository;
+import org.sufficientlysecure.keychain.daos.KeyRepository.NotFoundException;
 import org.sufficientlysecure.keychain.model.SubKey.UnifiedKeyInfo;
 import org.sufficientlysecure.keychain.operations.results.ExportResult;
 import org.sufficientlysecure.keychain.operations.results.OperationResult.LogType;
@@ -50,8 +52,6 @@ import org.sufficientlysecure.keychain.pgp.PgpSignEncryptOperation;
 import org.sufficientlysecure.keychain.pgp.Progressable;
 import org.sufficientlysecure.keychain.pgp.UncachedKeyRing;
 import org.sufficientlysecure.keychain.pgp.exception.PgpGeneralException;
-import org.sufficientlysecure.keychain.daos.KeyRepository;
-import org.sufficientlysecure.keychain.daos.KeyRepository.NotFoundException;
 import org.sufficientlysecure.keychain.provider.TemporaryFileProvider;
 import org.sufficientlysecure.keychain.service.BackupKeyringParcel;
 import org.sufficientlysecure.keychain.service.input.CryptoInputParcel;
@@ -83,7 +83,7 @@ public class BackupOperation extends BaseOperation<BackupKeyringParcel> {
     }
 
     public BackupOperation(Context context, KeyRepository keyRepository,
-                           Progressable progressable, CancellationSignal cancelled) {
+                           Progressable progressable, AtomicBoolean cancelled) {
         super(context, keyRepository, progressable, cancelled);
     }
 
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/BaseOperation.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/BaseOperation.java
index f757eb6dd..693d6dd11 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/BaseOperation.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/BaseOperation.java
@@ -18,17 +18,18 @@
 package org.sufficientlysecure.keychain.operations;
 
 
+import java.util.concurrent.atomic.AtomicBoolean;
+
 import android.content.Context;
 import android.os.Parcelable;
 import android.support.annotation.NonNull;
 import android.support.annotation.StringRes;
-import android.support.v4.os.CancellationSignal;
 
 import org.sufficientlysecure.keychain.Constants.key;
+import org.sufficientlysecure.keychain.daos.KeyRepository;
 import org.sufficientlysecure.keychain.operations.results.OperationResult;
 import org.sufficientlysecure.keychain.pgp.PassphraseCacheInterface;
 import org.sufficientlysecure.keychain.pgp.Progressable;
-import org.sufficientlysecure.keychain.daos.KeyRepository;
 import org.sufficientlysecure.keychain.service.PassphraseCacheService;
 import org.sufficientlysecure.keychain.service.input.CryptoInputParcel;
 import org.sufficientlysecure.keychain.util.Passphrase;
@@ -37,7 +38,7 @@ public abstract class BaseOperation<T extends Parcelable> implements PassphraseC
 
     final public Context mContext;
     final public Progressable mProgressable;
-    final public CancellationSignal mCancelled;
+    final public AtomicBoolean mCancelled;
 
     final public KeyRepository mKeyRepository;
 
@@ -71,7 +72,7 @@ public abstract class BaseOperation<T extends Parcelable> implements PassphraseC
     }
 
     public BaseOperation(Context context, KeyRepository keyRepository,
-            Progressable progressable, CancellationSignal cancelled) {
+            Progressable progressable, AtomicBoolean cancelled) {
         mContext = context;
         mProgressable = progressable;
         mKeyRepository = keyRepository;
@@ -100,7 +101,7 @@ public abstract class BaseOperation<T extends Parcelable> implements PassphraseC
     }
 
     protected boolean checkCancelled() {
-        return mCancelled != null && mCancelled.isCanceled();
+        return mCancelled != null && mCancelled.get();
     }
 
     protected void setPreventCancel () {
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/BaseReadWriteOperation.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/BaseReadWriteOperation.java
index 43df20fb1..ec90c9158 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/BaseReadWriteOperation.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/BaseReadWriteOperation.java
@@ -18,12 +18,13 @@
 package org.sufficientlysecure.keychain.operations;
 
 
+import java.util.concurrent.atomic.AtomicBoolean;
+
 import android.content.Context;
 import android.os.Parcelable;
-import android.support.v4.os.CancellationSignal;
 
-import org.sufficientlysecure.keychain.pgp.Progressable;
 import org.sufficientlysecure.keychain.daos.KeyWritableRepository;
+import org.sufficientlysecure.keychain.pgp.Progressable;
 
 public abstract class BaseReadWriteOperation<T extends Parcelable> extends BaseOperation<T> {
     protected final KeyWritableRepository mKeyWritableRepository;
@@ -37,7 +38,7 @@ public abstract class BaseReadWriteOperation<T extends Parcelable> extends BaseO
     }
 
     protected BaseReadWriteOperation(Context context, KeyWritableRepository databaseInteractor,
-            Progressable progressable, CancellationSignal cancelled) {
+            Progressable progressable, AtomicBoolean cancelled) {
         super(context, databaseInteractor, progressable, cancelled);
 
         mKeyWritableRepository = databaseInteractor;
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/CertifyOperation.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/CertifyOperation.java
index b9a657cd8..87eaccd8f 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/CertifyOperation.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/CertifyOperation.java
@@ -19,11 +19,14 @@ package org.sufficientlysecure.keychain.operations;
 
 
 import java.util.ArrayList;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import android.content.Context;
 import android.support.annotation.NonNull;
-import android.support.v4.os.CancellationSignal;
 
+import org.sufficientlysecure.keychain.daos.KeyMetadataDao;
+import org.sufficientlysecure.keychain.daos.KeyRepository.NotFoundException;
+import org.sufficientlysecure.keychain.daos.KeyWritableRepository;
 import org.sufficientlysecure.keychain.operations.results.CertifyResult;
 import org.sufficientlysecure.keychain.operations.results.OperationResult.LogType;
 import org.sufficientlysecure.keychain.operations.results.OperationResult.OperationLog;
@@ -38,9 +41,6 @@ import org.sufficientlysecure.keychain.pgp.PgpCertifyOperation.PgpCertifyResult;
 import org.sufficientlysecure.keychain.pgp.Progressable;
 import org.sufficientlysecure.keychain.pgp.UncachedKeyRing;
 import org.sufficientlysecure.keychain.pgp.exception.PgpGeneralException;
-import org.sufficientlysecure.keychain.daos.KeyMetadataDao;
-import org.sufficientlysecure.keychain.daos.KeyRepository.NotFoundException;
-import org.sufficientlysecure.keychain.daos.KeyWritableRepository;
 import org.sufficientlysecure.keychain.service.CertifyActionsParcel;
 import org.sufficientlysecure.keychain.service.CertifyActionsParcel.CertifyAction;
 import org.sufficientlysecure.keychain.service.ContactSyncAdapterService;
@@ -63,8 +63,8 @@ import org.sufficientlysecure.keychain.util.Passphrase;
 public class CertifyOperation extends BaseReadWriteOperation<CertifyActionsParcel> {
     private final KeyMetadataDao keyMetadataDao;
 
-    public CertifyOperation(Context context, KeyWritableRepository keyWritableRepository, Progressable progressable, CancellationSignal
-            cancelled) {
+    public CertifyOperation(Context context, KeyWritableRepository keyWritableRepository, Progressable progressable,
+            AtomicBoolean cancelled) {
         super(context, keyWritableRepository, progressable, cancelled);
 
         this.keyMetadataDao = KeyMetadataDao.create(context);
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/EditKeyOperation.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/EditKeyOperation.java
index f0d10c7b5..053ca87b0 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/EditKeyOperation.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/EditKeyOperation.java
@@ -19,12 +19,15 @@ package org.sufficientlysecure.keychain.operations;
 
 
 import java.io.IOException;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import android.content.Context;
 import android.support.annotation.NonNull;
-import android.support.v4.os.CancellationSignal;
 
 import org.sufficientlysecure.keychain.R;
+import org.sufficientlysecure.keychain.daos.KeyMetadataDao;
+import org.sufficientlysecure.keychain.daos.KeyRepository.NotFoundException;
+import org.sufficientlysecure.keychain.daos.KeyWritableRepository;
 import org.sufficientlysecure.keychain.operations.results.EditKeyResult;
 import org.sufficientlysecure.keychain.operations.results.OperationResult.LogType;
 import org.sufficientlysecure.keychain.operations.results.OperationResult.OperationLog;
@@ -35,9 +38,6 @@ import org.sufficientlysecure.keychain.pgp.CanonicalizedSecretKeyRing;
 import org.sufficientlysecure.keychain.pgp.PgpKeyOperation;
 import org.sufficientlysecure.keychain.pgp.Progressable;
 import org.sufficientlysecure.keychain.pgp.UncachedKeyRing;
-import org.sufficientlysecure.keychain.daos.KeyMetadataDao;
-import org.sufficientlysecure.keychain.daos.KeyRepository.NotFoundException;
-import org.sufficientlysecure.keychain.daos.KeyWritableRepository;
 import org.sufficientlysecure.keychain.service.ContactSyncAdapterService;
 import org.sufficientlysecure.keychain.service.SaveKeyringParcel;
 import org.sufficientlysecure.keychain.service.UploadKeyringParcel;
@@ -61,7 +61,7 @@ public class EditKeyOperation extends BaseReadWriteOperation<SaveKeyringParcel>
 
 
     public EditKeyOperation(Context context, KeyWritableRepository databaseInteractor,
-                            Progressable progressable, CancellationSignal cancelled) {
+                            Progressable progressable, AtomicBoolean cancelled) {
         super(context, databaseInteractor, progressable, cancelled);
 
         this.keyMetadataDao = KeyMetadataDao.create(context);
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/ImportOperation.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/ImportOperation.java
index 189d596fd..452990673 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/ImportOperation.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/ImportOperation.java
@@ -29,13 +29,15 @@ import java.util.concurrent.ExecutorService;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import android.content.Context;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
-import android.support.v4.os.CancellationSignal;
 
 import org.sufficientlysecure.keychain.R;
+import org.sufficientlysecure.keychain.daos.KeyMetadataDao;
+import org.sufficientlysecure.keychain.daos.KeyWritableRepository;
 import org.sufficientlysecure.keychain.keyimport.FacebookKeyserverClient;
 import org.sufficientlysecure.keychain.keyimport.HkpKeyserverAddress;
 import org.sufficientlysecure.keychain.keyimport.HkpKeyserverClient;
@@ -54,8 +56,6 @@ import org.sufficientlysecure.keychain.pgp.CanonicalizedKeyRing;
 import org.sufficientlysecure.keychain.pgp.Progressable;
 import org.sufficientlysecure.keychain.pgp.UncachedKeyRing;
 import org.sufficientlysecure.keychain.pgp.exception.PgpGeneralException;
-import org.sufficientlysecure.keychain.daos.KeyMetadataDao;
-import org.sufficientlysecure.keychain.daos.KeyWritableRepository;
 import org.sufficientlysecure.keychain.service.ContactSyncAdapterService;
 import org.sufficientlysecure.keychain.service.ImportKeyringParcel;
 import org.sufficientlysecure.keychain.service.input.CryptoInputParcel;
@@ -102,7 +102,7 @@ public class ImportOperation extends BaseReadWriteOperation<ImportKeyringParcel>
     }
 
     public ImportOperation(Context context, KeyWritableRepository databaseInteractor,
-                           Progressable progressable, CancellationSignal cancelled) {
+                           Progressable progressable, AtomicBoolean cancelled) {
         super(context, databaseInteractor, progressable, cancelled);
 
         this.keyMetadataDao = KeyMetadataDao.create(context);
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/KeySyncOperation.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/KeySyncOperation.java
index ba4f5d79e..e97a31bf4 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/KeySyncOperation.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/KeySyncOperation.java
@@ -5,18 +5,18 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Random;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import android.content.Context;
 import android.support.annotation.NonNull;
-import android.support.v4.os.CancellationSignal;
 
 import org.sufficientlysecure.keychain.Constants;
+import org.sufficientlysecure.keychain.daos.KeyMetadataDao;
+import org.sufficientlysecure.keychain.daos.KeyWritableRepository;
 import org.sufficientlysecure.keychain.keyimport.ParcelableKeyRing;
 import org.sufficientlysecure.keychain.operations.results.ImportKeyResult;
 import org.sufficientlysecure.keychain.operations.results.OperationResult;
 import org.sufficientlysecure.keychain.pgp.Progressable;
-import org.sufficientlysecure.keychain.daos.KeyMetadataDao;
-import org.sufficientlysecure.keychain.daos.KeyWritableRepository;
 import org.sufficientlysecure.keychain.service.ImportKeyringParcel;
 import org.sufficientlysecure.keychain.service.input.CryptoInputParcel;
 import org.sufficientlysecure.keychain.ui.util.KeyFormattingUtils;
@@ -36,7 +36,7 @@ public class KeySyncOperation extends BaseReadWriteOperation<KeySyncParcel> {
     private final Preferences preferences;
 
     public KeySyncOperation(Context context, KeyWritableRepository databaseInteractor,
-            Progressable progressable, CancellationSignal cancellationSignal) {
+            Progressable progressable, AtomicBoolean cancellationSignal) {
         super(context, databaseInteractor, progressable, cancellationSignal);
 
         keyMetadataDao = KeyMetadataDao.create(context);
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/PromoteKeyOperation.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/PromoteKeyOperation.java
index fb4f350b2..b1126cf2f 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/PromoteKeyOperation.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/PromoteKeyOperation.java
@@ -20,12 +20,14 @@ package org.sufficientlysecure.keychain.operations;
 
 import java.util.Arrays;
 import java.util.List;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import android.content.Context;
 import android.support.annotation.NonNull;
-import android.support.v4.os.CancellationSignal;
 
 import org.sufficientlysecure.keychain.R;
+import org.sufficientlysecure.keychain.daos.KeyRepository.NotFoundException;
+import org.sufficientlysecure.keychain.daos.KeyWritableRepository;
 import org.sufficientlysecure.keychain.operations.results.OperationResult.LogType;
 import org.sufficientlysecure.keychain.operations.results.OperationResult.OperationLog;
 import org.sufficientlysecure.keychain.operations.results.PgpEditKeyResult;
@@ -35,8 +37,6 @@ import org.sufficientlysecure.keychain.pgp.CanonicalizedPublicKey;
 import org.sufficientlysecure.keychain.pgp.CanonicalizedPublicKeyRing;
 import org.sufficientlysecure.keychain.pgp.Progressable;
 import org.sufficientlysecure.keychain.pgp.UncachedKeyRing;
-import org.sufficientlysecure.keychain.daos.KeyRepository.NotFoundException;
-import org.sufficientlysecure.keychain.daos.KeyWritableRepository;
 import org.sufficientlysecure.keychain.service.PromoteKeyringParcel;
 import org.sufficientlysecure.keychain.service.input.CryptoInputParcel;
 import org.sufficientlysecure.keychain.ui.util.KeyFormattingUtils;
@@ -50,7 +50,7 @@ import org.sufficientlysecure.keychain.ui.util.KeyFormattingUtils;
  */
 public class PromoteKeyOperation extends BaseReadWriteOperation<PromoteKeyringParcel> {
     public PromoteKeyOperation(Context context, KeyWritableRepository databaseInteractor,
-                               Progressable progressable, CancellationSignal cancelled) {
+                               Progressable progressable, AtomicBoolean cancelled) {
         super(context, databaseInteractor, progressable, cancelled);
     }
 
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/SignEncryptOperation.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/SignEncryptOperation.java
index 306003b6e..20bcd19e8 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/SignEncryptOperation.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/SignEncryptOperation.java
@@ -20,12 +20,13 @@ package org.sufficientlysecure.keychain.operations;
 
 import java.util.ArrayDeque;
 import java.util.ArrayList;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import android.content.Context;
 import android.net.Uri;
 import android.support.annotation.NonNull;
-import android.support.v4.os.CancellationSignal;
 
+import org.sufficientlysecure.keychain.daos.KeyRepository;
 import org.sufficientlysecure.keychain.operations.results.OperationResult.LogType;
 import org.sufficientlysecure.keychain.operations.results.OperationResult.OperationLog;
 import org.sufficientlysecure.keychain.operations.results.PgpSignEncryptResult;
@@ -34,7 +35,6 @@ import org.sufficientlysecure.keychain.pgp.PgpSignEncryptInputParcel;
 import org.sufficientlysecure.keychain.pgp.PgpSignEncryptOperation;
 import org.sufficientlysecure.keychain.pgp.Progressable;
 import org.sufficientlysecure.keychain.pgp.SignEncryptParcel;
-import org.sufficientlysecure.keychain.daos.KeyRepository;
 import org.sufficientlysecure.keychain.service.input.CryptoInputParcel;
 import org.sufficientlysecure.keychain.service.input.RequiredInputParcel;
 import org.sufficientlysecure.keychain.service.input.RequiredInputParcel.RequiredInputType;
@@ -52,7 +52,7 @@ import org.sufficientlysecure.keychain.util.ProgressScaler;
 public class SignEncryptOperation extends BaseOperation<SignEncryptParcel> {
 
     public SignEncryptOperation(Context context, KeyRepository keyRepository,
-                                Progressable progressable, CancellationSignal cancelled) {
+                                Progressable progressable, AtomicBoolean cancelled) {
         super(context, keyRepository, progressable, cancelled);
     }
 
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/UploadOperation.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/UploadOperation.java
index 221d7af64..f7c70e671 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/UploadOperation.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/UploadOperation.java
@@ -21,11 +21,11 @@ package org.sufficientlysecure.keychain.operations;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.net.Proxy;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import android.content.Context;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
-import android.support.v4.os.CancellationSignal;
 
 import org.bouncycastle.bcpg.ArmoredOutputStream;
 import org.sufficientlysecure.keychain.R;
@@ -60,7 +60,7 @@ public class UploadOperation extends BaseOperation<UploadKeyringParcel> {
     private KeyMetadataDao keyMetadataDao;
 
     public UploadOperation(Context context, KeyRepository keyRepository,
-            Progressable progressable, CancellationSignal cancelled) {
+            Progressable progressable, AtomicBoolean cancelled) {
         super(context, keyRepository, progressable, cancelled);
 
         keyMetadataDao = KeyMetadataDao.create(mContext);
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpKeyOperation.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpKeyOperation.java
index 8fd9867cf..47fdd57fa 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpKeyOperation.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpKeyOperation.java
@@ -33,8 +33,7 @@ import java.util.Date;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Stack;
-
-import android.support.v4.os.CancellationSignal;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import org.bouncycastle.asn1.ASN1ObjectIdentifier;
 import org.bouncycastle.asn1.nist.NISTNamedCurves;
@@ -109,7 +108,7 @@ import timber.log.Timber;
 public class PgpKeyOperation {
 
     private Stack<Progressable> mProgress;
-    private CancellationSignal mCancelled;
+    private AtomicBoolean mCancelled;
 
     public PgpKeyOperation(Progressable progress) {
         super();
@@ -119,13 +118,13 @@ public class PgpKeyOperation {
         }
     }
 
-    public PgpKeyOperation(Progressable progress, CancellationSignal cancelled) {
+    public PgpKeyOperation(Progressable progress, AtomicBoolean cancelled) {
         this(progress);
         mCancelled = cancelled;
     }
 
     private boolean checkCancelled() {
-        return mCancelled != null && mCancelled.isCanceled();
+        return mCancelled != null && mCancelled.get();
     }
 
     private void subProgressPush(int from, int to) {
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpSignEncryptOperation.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpSignEncryptOperation.java
index 9d071fc4b..038cbf01a 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpSignEncryptOperation.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpSignEncryptOperation.java
@@ -33,11 +33,11 @@ import java.security.SignatureException;
 import java.util.Collection;
 import java.util.Date;
 import java.util.Set;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import android.content.Context;
 import android.net.Uri;
 import android.support.annotation.NonNull;
-import android.support.v4.os.CancellationSignal;
 
 import org.bouncycastle.bcpg.ArmoredOutputStream;
 import org.bouncycastle.bcpg.BCPGOutputStream;
@@ -54,6 +54,9 @@ import org.bouncycastle.openpgp.operator.jcajce.NfcSyncPGPContentSignerBuilder;
 import org.bouncycastle.openpgp.operator.jcajce.PGPUtil;
 import org.sufficientlysecure.keychain.Constants;
 import org.sufficientlysecure.keychain.R;
+import org.sufficientlysecure.keychain.daos.KeyRepository;
+import org.sufficientlysecure.keychain.daos.KeyRepository.NotFoundException;
+import org.sufficientlysecure.keychain.daos.KeyWritableRepository;
 import org.sufficientlysecure.keychain.operations.BaseOperation;
 import org.sufficientlysecure.keychain.operations.results.OperationResult.LogType;
 import org.sufficientlysecure.keychain.operations.results.OperationResult.OperationLog;
@@ -63,9 +66,6 @@ import org.sufficientlysecure.keychain.pgp.PgpSecurityConstants.OpenKeychainComp
 import org.sufficientlysecure.keychain.pgp.PgpSecurityConstants.OpenKeychainHashAlgorithmTags;
 import org.sufficientlysecure.keychain.pgp.PgpSecurityConstants.OpenKeychainSymmetricKeyAlgorithmTags;
 import org.sufficientlysecure.keychain.pgp.exception.PgpGeneralException;
-import org.sufficientlysecure.keychain.daos.KeyRepository;
-import org.sufficientlysecure.keychain.daos.KeyRepository.NotFoundException;
-import org.sufficientlysecure.keychain.daos.KeyWritableRepository;
 import org.sufficientlysecure.keychain.service.input.CryptoInputParcel;
 import org.sufficientlysecure.keychain.service.input.RequiredInputParcel;
 import org.sufficientlysecure.keychain.ui.util.KeyFormattingUtils;
@@ -104,7 +104,7 @@ public class PgpSignEncryptOperation extends BaseOperation<PgpSignEncryptInputPa
         }
     }
 
-    public PgpSignEncryptOperation(Context context, KeyRepository keyRepository, Progressable progressable, CancellationSignal cancelled) {
+    public PgpSignEncryptOperation(Context context, KeyRepository keyRepository, Progressable progressable, AtomicBoolean cancelled) {
         super(context, keyRepository, progressable, cancelled);
     }
 
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/service/KeychainService.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/service/KeychainService.java
index bdaee7166..08416abb9 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/service/KeychainService.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/service/KeychainService.java
@@ -18,18 +18,15 @@
 package org.sufficientlysecure.keychain.service;
 
 
-import android.app.Service;
-import android.content.Intent;
-import android.os.Bundle;
-import android.os.IBinder;
-import android.os.Message;
-import android.os.Messenger;
-import android.os.Parcelable;
-import android.os.RemoteException;
-import android.support.v4.os.CancellationSignal;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
 
-import org.sufficientlysecure.keychain.operations.KeySyncOperation;
-import org.sufficientlysecure.keychain.operations.KeySyncParcel;
+import android.content.Context;
+import android.os.Parcelable;
+
+import org.sufficientlysecure.keychain.daos.KeyWritableRepository;
 import org.sufficientlysecure.keychain.operations.BackupOperation;
 import org.sufficientlysecure.keychain.operations.BaseOperation;
 import org.sufficientlysecure.keychain.operations.BenchmarkOperation;
@@ -39,6 +36,8 @@ import org.sufficientlysecure.keychain.operations.DeleteOperation;
 import org.sufficientlysecure.keychain.operations.EditKeyOperation;
 import org.sufficientlysecure.keychain.operations.ImportOperation;
 import org.sufficientlysecure.keychain.operations.InputDataOperation;
+import org.sufficientlysecure.keychain.operations.KeySyncOperation;
+import org.sufficientlysecure.keychain.operations.KeySyncParcel;
 import org.sufficientlysecure.keychain.operations.KeybaseVerificationOperation;
 import org.sufficientlysecure.keychain.operations.PromoteKeyOperation;
 import org.sufficientlysecure.keychain.operations.RevokeOperation;
@@ -49,180 +48,88 @@ import org.sufficientlysecure.keychain.pgp.PgpDecryptVerifyInputParcel;
 import org.sufficientlysecure.keychain.pgp.PgpDecryptVerifyOperation;
 import org.sufficientlysecure.keychain.pgp.Progressable;
 import org.sufficientlysecure.keychain.pgp.SignEncryptParcel;
-import org.sufficientlysecure.keychain.daos.KeyWritableRepository;
-import org.sufficientlysecure.keychain.service.ServiceProgressHandler.MessageStatus;
 import org.sufficientlysecure.keychain.service.input.CryptoInputParcel;
-import timber.log.Timber;
 
 
-/**
- * This Service contains all important long lasting operations for OpenKeychain. It receives Intents with
- * data from the activities or other apps, executes them, and stops itself after doing them.
- */
-public class KeychainService extends Service implements Progressable {
+public class KeychainService {
+    private static KeychainService keychainService;
 
-    // messenger for communication (hack)
-    public static final String EXTRA_MESSENGER = "messenger";
+    public static KeychainService getInstance(Context context) {
+        if (keychainService == null) {
+            keychainService = new KeychainService(context.getApplicationContext());
+        }
+        return keychainService;
+    }
 
-    // extras for operation
-    public static final String EXTRA_OPERATION_INPUT = "op_input";
-    public static final String EXTRA_CRYPTO_INPUT = "crypto_input";
+    private KeychainService(Context context) {
+        this.context = context;
+        this.threadPoolExecutor = new ThreadPoolExecutor(0, 4, 1000, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<>());
+        this.keyRepository = KeyWritableRepository.create(context);
+    }
 
-    public static final String ACTION_CANCEL = "action_cancel";
+    private final Context context;
+    private final ThreadPoolExecutor threadPoolExecutor;
+    private final KeyWritableRepository keyRepository;
 
     // this attribute can possibly merged with the one above? not sure...
-    private CancellationSignal mActionCanceled;
+    private AtomicBoolean operationCancelledBoolean = new AtomicBoolean(false);
 
-    ThreadLocal<Messenger> mMessenger = new ThreadLocal<>();
+    public void startOperationInBackground(Parcelable inputParcel, CryptoInputParcel cryptoInput,
+            Progressable progressable, OperationCallback operationCallback) {
+        operationCancelledBoolean.set(false);
 
-    @Override
-    public IBinder onBind(Intent intent) {
-        return null;
-    }
+        Runnable actionRunnable = () -> {
+            BaseOperation op;
 
-    /**
-     * This is run on the main thread, we need to spawn a runnable which runs on another thread for the actual operation
-     */
-    @Override
-    public int onStartCommand(final Intent intent, int flags, int startId) {
-
-        if (intent.getAction() != null && intent.getAction().equals(ACTION_CANCEL)) {
-            if (mActionCanceled != null) {
-                mActionCanceled.cancel();
+            if (inputParcel instanceof SignEncryptParcel) {
+                op = new SignEncryptOperation(context, keyRepository, progressable, operationCancelledBoolean);
+            } else if (inputParcel instanceof PgpDecryptVerifyInputParcel) {
+                op = new PgpDecryptVerifyOperation(context, keyRepository, progressable);
+            } else if (inputParcel instanceof SaveKeyringParcel) {
+                op = new EditKeyOperation(context, keyRepository, progressable, operationCancelledBoolean);
+            } else if (inputParcel instanceof  ChangeUnlockParcel) {
+                op = new ChangeUnlockOperation(context, keyRepository, progressable);
+            } else if (inputParcel instanceof RevokeKeyringParcel) {
+                op = new RevokeOperation(context, keyRepository, progressable);
+            } else if (inputParcel instanceof CertifyActionsParcel) {
+                op = new CertifyOperation(context, keyRepository, progressable, operationCancelledBoolean);
+            } else if (inputParcel instanceof DeleteKeyringParcel) {
+                op = new DeleteOperation(context, keyRepository, progressable);
+            } else if (inputParcel instanceof PromoteKeyringParcel) {
+                op = new PromoteKeyOperation(context, keyRepository, progressable, operationCancelledBoolean);
+            } else if (inputParcel instanceof ImportKeyringParcel) {
+                op = new ImportOperation(context, keyRepository, progressable, operationCancelledBoolean);
+            } else if (inputParcel instanceof BackupKeyringParcel) {
+                op = new BackupOperation(context, keyRepository, progressable, operationCancelledBoolean);
+            } else if (inputParcel instanceof UploadKeyringParcel) {
+                op = new UploadOperation(context, keyRepository, progressable, operationCancelledBoolean);
+            } else if (inputParcel instanceof KeybaseVerificationParcel) {
+                op = new KeybaseVerificationOperation(context, keyRepository, progressable);
+            } else if (inputParcel instanceof InputDataParcel) {
+                op = new InputDataOperation(context, keyRepository, progressable);
+            } else if (inputParcel instanceof BenchmarkInputParcel) {
+                op = new BenchmarkOperation(context, keyRepository, progressable);
+            } else if (inputParcel instanceof KeySyncParcel) {
+                op = new KeySyncOperation(context, keyRepository, progressable, operationCancelledBoolean);
+            } else {
+                throw new AssertionError("Unrecognized input parcel in KeychainService!");
             }
-            return START_NOT_STICKY;
-        }
 
-        mActionCanceled = new CancellationSignal();
-
-        Runnable actionRunnable = new Runnable() {
-            @Override
-            public void run() {
-                Bundle extras = intent.getExtras();
-
-                // Set messenger for communication (for this particular thread)
-                mMessenger.set(extras.getParcelable(EXTRA_MESSENGER));
-
-                // Input
-                Parcelable inputParcel = extras.getParcelable(EXTRA_OPERATION_INPUT);
-                CryptoInputParcel cryptoInput = extras.getParcelable(EXTRA_CRYPTO_INPUT);
-
-                // Operation
-                BaseOperation op;
-
-                // just for brevity
-                KeychainService outerThis = KeychainService.this;
-                KeyWritableRepository databaseInteractor =
-                        KeyWritableRepository.create(outerThis);
-                if (inputParcel instanceof SignEncryptParcel) {
-                    op = new SignEncryptOperation(outerThis, databaseInteractor, outerThis, mActionCanceled);
-                } else if (inputParcel instanceof PgpDecryptVerifyInputParcel) {
-                    op = new PgpDecryptVerifyOperation(outerThis, databaseInteractor, outerThis);
-                } else if (inputParcel instanceof SaveKeyringParcel) {
-                    op = new EditKeyOperation(outerThis, databaseInteractor, outerThis, mActionCanceled);
-                } else if (inputParcel instanceof  ChangeUnlockParcel) {
-                    op = new ChangeUnlockOperation(outerThis, databaseInteractor, outerThis);
-                } else if (inputParcel instanceof RevokeKeyringParcel) {
-                    op = new RevokeOperation(outerThis, databaseInteractor, outerThis);
-                } else if (inputParcel instanceof CertifyActionsParcel) {
-                    op = new CertifyOperation(outerThis, databaseInteractor, outerThis, mActionCanceled);
-                } else if (inputParcel instanceof DeleteKeyringParcel) {
-                    op = new DeleteOperation(outerThis, databaseInteractor, outerThis);
-                } else if (inputParcel instanceof PromoteKeyringParcel) {
-                    op = new PromoteKeyOperation(outerThis, databaseInteractor, outerThis, mActionCanceled);
-                } else if (inputParcel instanceof ImportKeyringParcel) {
-                    op = new ImportOperation(outerThis, databaseInteractor, outerThis, mActionCanceled);
-                } else if (inputParcel instanceof BackupKeyringParcel) {
-                    op = new BackupOperation(outerThis, databaseInteractor, outerThis, mActionCanceled);
-                } else if (inputParcel instanceof UploadKeyringParcel) {
-                    op = new UploadOperation(outerThis, databaseInteractor, outerThis, mActionCanceled);
-                } else if (inputParcel instanceof KeybaseVerificationParcel) {
-                    op = new KeybaseVerificationOperation(outerThis, databaseInteractor, outerThis);
-                } else if (inputParcel instanceof InputDataParcel) {
-                    op = new InputDataOperation(outerThis, databaseInteractor, outerThis);
-                } else if (inputParcel instanceof BenchmarkInputParcel) {
-                    op = new BenchmarkOperation(outerThis, databaseInteractor, outerThis);
-                } else if (inputParcel instanceof KeySyncParcel) {
-                    op = new KeySyncOperation(outerThis, databaseInteractor, outerThis, mActionCanceled);
-                } else {
-                    throw new AssertionError("Unrecognized input parcel in KeychainService!");
-                }
-
-                @SuppressWarnings("unchecked") // this is unchecked, we make sure it's the correct op above!
-                OperationResult result = op.execute(inputParcel, cryptoInput);
-                sendMessageToHandler(MessageStatus.OKAY, result);
-
-            }
+            @SuppressWarnings("unchecked") // this is unchecked, we make sure it's the correct op above!
+            OperationResult result = op.execute(inputParcel, cryptoInput);
+            operationCallback.operationFinished(result);
         };
 
-        Thread actionThread = new Thread(actionRunnable);
-        actionThread.start();
-
-        return START_NOT_STICKY;
+        threadPoolExecutor.execute(actionRunnable);
     }
 
-    private void sendMessageToHandler(MessageStatus status, Integer arg2, Bundle data) {
-
-        Message msg = Message.obtain();
-        assert msg != null;
-        msg.arg1 = status.ordinal();
-        if (arg2 != null) {
-            msg.arg2 = arg2;
-        }
-        if (data != null) {
-            msg.setData(data);
-        }
-
-        try {
-            mMessenger.get().send(msg);
-        } catch (RemoteException e) {
-            Timber.w(e, "Exception sending message, Is handler present?");
-        } catch (NullPointerException e) {
-            Timber.w(e, "Messenger is null!");
+    public void cancelRunningTask() {
+        if (operationCancelledBoolean != null) {
+            operationCancelledBoolean.set(true);
         }
     }
 
-    private void sendMessageToHandler(MessageStatus status, OperationResult data) {
-        Bundle bundle = new Bundle();
-        bundle.putParcelable(OperationResult.EXTRA_RESULT, data);
-        sendMessageToHandler(status, null, bundle);
+    public interface OperationCallback {
+        void operationFinished(OperationResult data);
     }
-
-    private void sendMessageToHandler(MessageStatus status) {
-        sendMessageToHandler(status, null, null);
-    }
-
-    /**
-     * Set progress of ProgressDialog by sending message to handler on UI thread
-     */
-    @Override
-    public void setProgress(String message, int progress, int max) {
-        Timber.d("Send message by setProgress with progress=" + progress + ", max="
-                + max);
-
-        Bundle data = new Bundle();
-        if (message != null) {
-            data.putString(ServiceProgressHandler.DATA_MESSAGE, message);
-        }
-        data.putInt(ServiceProgressHandler.DATA_PROGRESS, progress);
-        data.putInt(ServiceProgressHandler.DATA_PROGRESS_MAX, max);
-
-        sendMessageToHandler(MessageStatus.UPDATE_PROGRESS, null, data);
-    }
-
-    @Override
-    public void setProgress(int resourceId, int progress, int max) {
-        setProgress(getString(resourceId), progress, max);
-    }
-
-    @Override
-    public void setProgress(int progress, int max) {
-        setProgress(null, progress, max);
-    }
-
-    @Override
-    public void setPreventCancel() {
-        sendMessageToHandler(MessageStatus.PREVENT_CANCEL);
-    }
-
 }
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/base/CryptoOperationFragment.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/base/CryptoOperationFragment.java
index 13b62752e..92aaeda39 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/base/CryptoOperationFragment.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/base/CryptoOperationFragment.java
@@ -29,7 +29,6 @@ import android.view.inputmethod.InputMethodManager;
 
 import org.sufficientlysecure.keychain.R;
 import org.sufficientlysecure.keychain.operations.results.OperationResult;
-import org.sufficientlysecure.keychain.service.KeychainService;
 import org.sufficientlysecure.keychain.service.input.CryptoInputParcel;
 
 /** This is a base class for fragments which implement a cryptoOperation.
@@ -47,8 +46,6 @@ import org.sufficientlysecure.keychain.service.input.CryptoInputParcel;
  * must override at least onCryptoOperationSuccess to proceed after a
  * successful operation.
  *
- * @see KeychainService
- *
  */
 public abstract class CryptoOperationFragment<T extends Parcelable, S extends OperationResult>
         extends Fragment implements CryptoOperationHelper.Callback<T, S> {
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/base/CryptoOperationHelper.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/base/CryptoOperationHelper.java
index 06dc54345..374dda3aa 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/base/CryptoOperationHelper.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/base/CryptoOperationHelper.java
@@ -17,6 +17,7 @@
 
 package org.sufficientlysecure.keychain.ui.base;
 
+
 import java.util.Date;
 
 import android.app.Activity;
@@ -27,6 +28,7 @@ import android.os.Handler;
 import android.os.Message;
 import android.os.Messenger;
 import android.os.Parcelable;
+import android.os.RemoteException;
 import android.os.SystemClock;
 import android.support.v4.app.Fragment;
 import android.support.v4.app.FragmentActivity;
@@ -34,14 +36,17 @@ import android.support.v4.app.FragmentManager;
 
 import org.sufficientlysecure.keychain.operations.results.InputPendingResult;
 import org.sufficientlysecure.keychain.operations.results.OperationResult;
+import org.sufficientlysecure.keychain.pgp.Progressable;
 import org.sufficientlysecure.keychain.service.KeychainService;
+import org.sufficientlysecure.keychain.service.KeychainService.OperationCallback;
 import org.sufficientlysecure.keychain.service.ServiceProgressHandler;
+import org.sufficientlysecure.keychain.service.ServiceProgressHandler.MessageStatus;
 import org.sufficientlysecure.keychain.service.input.CryptoInputParcel;
 import org.sufficientlysecure.keychain.service.input.RequiredInputParcel;
-import org.sufficientlysecure.keychain.ui.SecurityTokenOperationActivity;
 import org.sufficientlysecure.keychain.ui.OrbotRequiredDialogActivity;
 import org.sufficientlysecure.keychain.ui.PassphraseDialogActivity;
 import org.sufficientlysecure.keychain.ui.RetryUploadDialogActivity;
+import org.sufficientlysecure.keychain.ui.SecurityTokenOperationActivity;
 import org.sufficientlysecure.keychain.ui.dialog.ProgressDialogFragment;
 import timber.log.Timber;
 
@@ -295,12 +300,6 @@ public class CryptoOperationHelper<T extends Parcelable, S extends OperationResu
             return;
         }
 
-        // Send all information needed to service to edit key in other thread
-        Intent intent = new Intent(activity, KeychainService.class);
-
-        intent.putExtra(KeychainService.EXTRA_OPERATION_INPUT, operationInput);
-        intent.putExtra(KeychainService.EXTRA_CRYPTO_INPUT, cryptoInput);
-
         ServiceProgressHandler saveHandler = new ServiceProgressHandler(activity) {
             @Override
             public void handleMessage(Message message) {
@@ -331,9 +330,39 @@ public class CryptoOperationHelper<T extends Parcelable, S extends OperationResu
             }
         };
 
-        // Create a new Messenger for the communication back
         Messenger messenger = new Messenger(saveHandler);
-        intent.putExtra(KeychainService.EXTRA_MESSENGER, messenger);
+        Communicator communicator = new Communicator(messenger);
+
+        Progressable progressable = new Progressable() {
+            @Override
+            public void setProgress(String message, int progress, int max) {
+                Timber.d("Send message by setProgress with progress=" + progress + ", max=" + max);
+
+                Bundle data = new Bundle();
+                if (message != null) {
+                    data.putString(ServiceProgressHandler.DATA_MESSAGE, message);
+                }
+                data.putInt(ServiceProgressHandler.DATA_PROGRESS, progress);
+                data.putInt(ServiceProgressHandler.DATA_PROGRESS_MAX, max);
+
+                communicator.sendMessageToHandler(MessageStatus.UPDATE_PROGRESS, data);
+            }
+
+            @Override
+            public void setProgress(int resourceId, int progress, int max) {
+                setProgress(activity.getString(resourceId), progress, max);
+            }
+
+            @Override
+            public void setProgress(int progress, int max) {
+                setProgress(null, progress, max);
+            }
+
+            @Override
+            public void setPreventCancel() {
+                communicator.sendMessageToHandler(MessageStatus.PREVENT_CANCEL, (Bundle) null);
+            }
+        };
 
         if (mProgressMessageResource != null) {
             saveHandler.showProgressDialog(
@@ -341,7 +370,8 @@ public class CryptoOperationHelper<T extends Parcelable, S extends OperationResu
                     ProgressDialog.STYLE_HORIZONTAL, mCancellable);
         }
 
-        activity.startService(intent);
+        KeychainService keychainService = KeychainService.getInstance(activity);
+        keychainService.startOperationInBackground(operationInput, cryptoInput, progressable, communicator);
     }
 
     public void cryptoOperation() {
@@ -391,4 +421,37 @@ public class CryptoOperationHelper<T extends Parcelable, S extends OperationResu
                     + result.getClass().getSimpleName() + "), this is a programming error!");
         }
     }
+
+    public static class Communicator implements OperationCallback {
+        final Messenger messenger;
+
+        Communicator(Messenger messenger) {
+            this.messenger = messenger;
+        }
+
+        public void sendMessageToHandler(MessageStatus status, Bundle data) {
+            Message msg = Message.obtain();
+            assert msg != null;
+            msg.arg1 = status.ordinal();
+            if (data != null) {
+                msg.setData(data);
+            }
+
+            try {
+                messenger.send(msg);
+            } catch (RemoteException e) {
+                Timber.w(e, "Exception sending message, Is handler present?");
+            } catch (NullPointerException e) {
+                Timber.w(e, "Messenger is null!");
+            }
+        }
+
+        @Override
+        public void operationFinished(OperationResult data) {
+            Bundle bundle = new Bundle();
+            bundle.putParcelable(OperationResult.EXTRA_RESULT, data);
+            sendMessageToHandler(MessageStatus.OKAY, bundle);
+        }
+    }
+
 }
\ No newline at end of file
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/dialog/ProgressDialogFragment.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/dialog/ProgressDialogFragment.java
index 5d48b7b09..414c8b144 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/dialog/ProgressDialogFragment.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/dialog/ProgressDialogFragment.java
@@ -176,13 +176,8 @@ public class ProgressDialogFragment extends DialogFragment {
                 negative.setClickable(false);
                 negative.setTextColor(Color.GRAY);
 
-                // send a cancel message. note that this message will be handled by
-                // KeychainService.onStartCommand, which runs in this thread,
-                // not the service one, and will not queue up a command.
-                Intent serviceIntent = new Intent(getActivity(), KeychainService.class);
-
-                serviceIntent.setAction(KeychainService.ACTION_CANCEL);
-                getActivity().startService(serviceIntent);
+                KeychainService keychainService = KeychainService.getInstance(requireContext());
+                keychainService.cancelRunningTask();
 
                 // Set the progress bar accordingly
                 ProgressDialog dialog = (ProgressDialog) getDialog();