Subtree merged in openpgp api lib

10 files changed, 1326 insertions, 6 deletions

diff --git a/libs/openpgp-api-lib b/libs/openpgp-api-lib
deleted file mode 160000
-Subproject 0be263d5d3effd2df5f976fa4a127017268749c
diff --git a/libs/openpgp-api-lib/src/org/openintents/openpgp/IOpenPgpService.aidl b/libs/openpgp-api-lib/src/org/openintents/openpgp/IOpenPgpService.aidl
new file mode 100644
index 00000000..7ee79d6a
--- /dev/null
+++ b/libs/openpgp-api-lib/src/org/openintents/openpgp/IOpenPgpService.aidl
@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2014 Dominik Schürmann <dominik@dominikschuermann.de>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+ 
+package org.openintents.openpgp;
+
+interface IOpenPgpService {
+
+    // see OpenPgpApi for documentation
+    Intent execute(in Intent data, in ParcelFileDescriptor input, in ParcelFileDescriptor output);
+
+}
\ No newline at end of file
diff --git a/libs/openpgp-api-lib/src/org/openintents/openpgp/OpenPgpError.java b/libs/openpgp-api-lib/src/org/openintents/openpgp/OpenPgpError.java
new file mode 100644
index 00000000..b894a460
--- /dev/null
+++ b/libs/openpgp-api-lib/src/org/openintents/openpgp/OpenPgpError.java
@@ -0,0 +1,118 @@
+/*
+ * Copyright (C) 2014 Dominik Schürmann <dominik@dominikschuermann.de>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.openintents.openpgp;
+
+import android.os.Parcel;
+import android.os.Parcelable;
+
+/**
+ * Parcelable versioning has been copied from Dashclock Widget
+ * https://code.google.com/p/dashclock/source/browse/api/src/main/java/com/google/android/apps/dashclock/api/ExtensionData.java
+ */
+public class OpenPgpError implements Parcelable {
+    /**
+     * Since there might be a case where new versions of the client using the library getting
+     * old versions of the protocol (and thus old versions of this class), we need a versioning
+     * system for the parcels sent between the clients and the providers.
+     */
+    public static final int PARCELABLE_VERSION = 1;
+
+    // possible values for errorId
+    public static final int CLIENT_SIDE_ERROR = -1;
+    public static final int GENERIC_ERROR = 0;
+    public static final int INCOMPATIBLE_API_VERSIONS = 1;
+    public static final int NO_OR_WRONG_PASSPHRASE = 2;
+    public static final int NO_USER_IDS = 3;
+
+    int errorId;
+    String message;
+
+    public OpenPgpError() {
+    }
+
+    public OpenPgpError(int errorId, String message) {
+        this.errorId = errorId;
+        this.message = message;
+    }
+
+    public OpenPgpError(OpenPgpError b) {
+        this.errorId = b.errorId;
+        this.message = b.message;
+    }
+
+    public int getErrorId() {
+        return errorId;
+    }
+
+    public void setErrorId(int errorId) {
+        this.errorId = errorId;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public void setMessage(String message) {
+        this.message = message;
+    }
+
+    public int describeContents() {
+        return 0;
+    }
+
+    public void writeToParcel(Parcel dest, int flags) {
+        /**
+         * NOTE: When adding fields in the process of updating this API, make sure to bump
+         * {@link #PARCELABLE_VERSION}.
+         */
+        dest.writeInt(PARCELABLE_VERSION);
+        // Inject a placeholder that will store the parcel size from this point on
+        // (not including the size itself).
+        int sizePosition = dest.dataPosition();
+        dest.writeInt(0);
+        int startPosition = dest.dataPosition();
+        // version 1
+        dest.writeInt(errorId);
+        dest.writeString(message);
+        // Go back and write the size
+        int parcelableSize = dest.dataPosition() - startPosition;
+        dest.setDataPosition(sizePosition);
+        dest.writeInt(parcelableSize);
+        dest.setDataPosition(startPosition + parcelableSize);
+    }
+
+    public static final Creator<OpenPgpError> CREATOR = new Creator<OpenPgpError>() {
+        public OpenPgpError createFromParcel(final Parcel source) {
+            int parcelableVersion = source.readInt();
+            int parcelableSize = source.readInt();
+            int startPosition = source.dataPosition();
+
+            OpenPgpError error = new OpenPgpError();
+            error.errorId = source.readInt();
+            error.message = source.readString();
+
+            // skip over all fields added in future versions of this parcel
+            source.setDataPosition(startPosition + parcelableSize);
+
+            return error;
+        }
+
+        public OpenPgpError[] newArray(final int size) {
+            return new OpenPgpError[size];
+        }
+    };
+}
diff --git a/libs/openpgp-api-lib/src/org/openintents/openpgp/OpenPgpMetadata.java b/libs/openpgp-api-lib/src/org/openintents/openpgp/OpenPgpMetadata.java
new file mode 100644
index 00000000..2a99e406
--- /dev/null
+++ b/libs/openpgp-api-lib/src/org/openintents/openpgp/OpenPgpMetadata.java
@@ -0,0 +1,132 @@
+/*
+ * Copyright (C) 2014 Dominik Schürmann <dominik@dominikschuermann.de>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.openintents.openpgp;
+
+import android.os.Parcel;
+import android.os.Parcelable;
+
+/**
+ * Parcelable versioning has been copied from Dashclock Widget
+ * https://code.google.com/p/dashclock/source/browse/api/src/main/java/com/google/android/apps/dashclock/api/ExtensionData.java
+ */
+public class OpenPgpMetadata implements Parcelable {
+    /**
+     * Since there might be a case where new versions of the client using the library getting
+     * old versions of the protocol (and thus old versions of this class), we need a versioning
+     * system for the parcels sent between the clients and the providers.
+     */
+    public static final int PARCELABLE_VERSION = 1;
+
+    String filename;
+    String mimeType;
+    long modificationTime;
+    long originalSize;
+
+    public String getFilename() {
+        return filename;
+    }
+
+    public String getMimeType() {
+        return mimeType;
+    }
+
+    public long getModificationTime() {
+        return modificationTime;
+    }
+
+    public long getOriginalSize() {
+        return originalSize;
+    }
+
+    public OpenPgpMetadata() {
+    }
+
+    public OpenPgpMetadata(String filename, String mimeType, long modificationTime,
+                           long originalSize) {
+        this.filename = filename;
+        this.mimeType = mimeType;
+        this.modificationTime = modificationTime;
+        this.originalSize = originalSize;
+    }
+
+    public OpenPgpMetadata(OpenPgpMetadata b) {
+        this.filename = b.filename;
+        this.mimeType = b.mimeType;
+        this.modificationTime = b.modificationTime;
+        this.originalSize = b.originalSize;
+    }
+
+    public int describeContents() {
+        return 0;
+    }
+
+    public void writeToParcel(Parcel dest, int flags) {
+        /**
+         * NOTE: When adding fields in the process of updating this API, make sure to bump
+         * {@link #PARCELABLE_VERSION}.
+         */
+        dest.writeInt(PARCELABLE_VERSION);
+        // Inject a placeholder that will store the parcel size from this point on
+        // (not including the size itself).
+        int sizePosition = dest.dataPosition();
+        dest.writeInt(0);
+        int startPosition = dest.dataPosition();
+        // version 1
+        dest.writeString(filename);
+        dest.writeString(mimeType);
+        dest.writeLong(modificationTime);
+        dest.writeLong(originalSize);
+        // Go back and write the size
+        int parcelableSize = dest.dataPosition() - startPosition;
+        dest.setDataPosition(sizePosition);
+        dest.writeInt(parcelableSize);
+        dest.setDataPosition(startPosition + parcelableSize);
+    }
+
+    public static final Creator<OpenPgpMetadata> CREATOR = new Creator<OpenPgpMetadata>() {
+        public OpenPgpMetadata createFromParcel(final Parcel source) {
+            int parcelableVersion = source.readInt();
+            int parcelableSize = source.readInt();
+            int startPosition = source.dataPosition();
+
+            OpenPgpMetadata vr = new OpenPgpMetadata();
+            vr.filename = source.readString();
+            vr.mimeType = source.readString();
+            vr.modificationTime = source.readLong();
+            vr.originalSize = source.readLong();
+
+            // skip over all fields added in future versions of this parcel
+            source.setDataPosition(startPosition + parcelableSize);
+
+            return vr;
+        }
+
+        public OpenPgpMetadata[] newArray(final int size) {
+            return new OpenPgpMetadata[size];
+        }
+    };
+
+    @Override
+    public String toString() {
+        String out = "\nfilename: " + filename;
+        out += "\nmimeType: " + mimeType;
+        out += "\nmodificationTime: " + modificationTime;
+        out += "\noriginalSize: " + originalSize;
+        return out;
+    }
+
+}
diff --git a/libs/openpgp-api-lib/src/org/openintents/openpgp/OpenPgpSignatureResult.java b/libs/openpgp-api-lib/src/org/openintents/openpgp/OpenPgpSignatureResult.java
new file mode 100644
index 00000000..dbcd74b6
--- /dev/null
+++ b/libs/openpgp-api-lib/src/org/openintents/openpgp/OpenPgpSignatureResult.java
@@ -0,0 +1,183 @@
+/*
+ * Copyright (C) 2014 Dominik Schürmann <dominik@dominikschuermann.de>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.openintents.openpgp;
+
+import android.os.Parcel;
+import android.os.Parcelable;
+
+import org.openintents.openpgp.util.OpenPgpUtils;
+
+import java.util.ArrayList;
+import java.util.Locale;
+
+/**
+ * Parcelable versioning has been copied from Dashclock Widget
+ * https://code.google.com/p/dashclock/source/browse/api/src/main/java/com/google/android/apps/dashclock/api/ExtensionData.java
+ */
+public class OpenPgpSignatureResult implements Parcelable {
+    /**
+     * Since there might be a case where new versions of the client using the library getting
+     * old versions of the protocol (and thus old versions of this class), we need a versioning
+     * system for the parcels sent between the clients and the providers.
+     */
+    public static final int PARCELABLE_VERSION = 2;
+
+    // generic error on signature verification
+    public static final int SIGNATURE_ERROR = 0;
+    // successfully verified signature, with certified key
+    public static final int SIGNATURE_SUCCESS_CERTIFIED = 1;
+    // no key was found for this signature verification
+    public static final int SIGNATURE_KEY_MISSING = 2;
+    // successfully verified signature, but with uncertified key
+    public static final int SIGNATURE_SUCCESS_UNCERTIFIED = 3;
+    // key has been revoked
+    public static final int SIGNATURE_KEY_REVOKED = 4;
+    // key is expired
+    public static final int SIGNATURE_KEY_EXPIRED = 5;
+
+    int status;
+    boolean signatureOnly;
+    String primaryUserId;
+    ArrayList<String> userIds;
+    long keyId;
+
+    public int getStatus() {
+        return status;
+    }
+
+    public void setStatus(int status) {
+        this.status = status;
+    }
+
+    public boolean isSignatureOnly() {
+        return signatureOnly;
+    }
+
+    public void setSignatureOnly(boolean signatureOnly) {
+        this.signatureOnly = signatureOnly;
+    }
+
+    public String getPrimaryUserId() {
+        return primaryUserId;
+    }
+
+    public void setPrimaryUserId(String primaryUserId) {
+        this.primaryUserId = primaryUserId;
+    }
+
+    public ArrayList<String> getUserIds() {
+        return userIds;
+    }
+
+    public void setUserIds(ArrayList<String> userIds) {
+        this.userIds = userIds;
+    }
+
+    public long getKeyId() {
+        return keyId;
+    }
+
+    public void setKeyId(long keyId) {
+        this.keyId = keyId;
+    }
+
+    public OpenPgpSignatureResult() {
+
+    }
+
+    public OpenPgpSignatureResult(int signatureStatus, String signatureUserId,
+                                  boolean signatureOnly, long keyId, ArrayList<String> userIds) {
+        this.status = signatureStatus;
+        this.signatureOnly = signatureOnly;
+        this.primaryUserId = signatureUserId;
+        this.keyId = keyId;
+        this.userIds = userIds;
+    }
+
+    public OpenPgpSignatureResult(OpenPgpSignatureResult b) {
+        this.status = b.status;
+        this.primaryUserId = b.primaryUserId;
+        this.signatureOnly = b.signatureOnly;
+        this.keyId = b.keyId;
+        this.userIds = b.userIds;
+    }
+
+    public int describeContents() {
+        return 0;
+    }
+
+    public void writeToParcel(Parcel dest, int flags) {
+        /**
+         * NOTE: When adding fields in the process of updating this API, make sure to bump
+         * {@link #PARCELABLE_VERSION}.
+         */
+        dest.writeInt(PARCELABLE_VERSION);
+        // Inject a placeholder that will store the parcel size from this point on
+        // (not including the size itself).
+        int sizePosition = dest.dataPosition();
+        dest.writeInt(0);
+        int startPosition = dest.dataPosition();
+        // version 1
+        dest.writeInt(status);
+        dest.writeByte((byte) (signatureOnly ? 1 : 0));
+        dest.writeString(primaryUserId);
+        dest.writeLong(keyId);
+        // version 2
+        dest.writeStringList(userIds);
+        // Go back and write the size
+        int parcelableSize = dest.dataPosition() - startPosition;
+        dest.setDataPosition(sizePosition);
+        dest.writeInt(parcelableSize);
+        dest.setDataPosition(startPosition + parcelableSize);
+    }
+
+    public static final Creator<OpenPgpSignatureResult> CREATOR = new Creator<OpenPgpSignatureResult>() {
+        public OpenPgpSignatureResult createFromParcel(final Parcel source) {
+            int parcelableVersion = source.readInt();
+            int parcelableSize = source.readInt();
+            int startPosition = source.dataPosition();
+
+            OpenPgpSignatureResult vr = new OpenPgpSignatureResult();
+            vr.status = source.readInt();
+            vr.signatureOnly = source.readByte() == 1;
+            vr.primaryUserId = source.readString();
+            vr.keyId = source.readLong();
+            vr.userIds = new ArrayList<String>();
+            source.readStringList(vr.userIds);
+
+            // skip over all fields added in future versions of this parcel
+            source.setDataPosition(startPosition + parcelableSize);
+
+            return vr;
+        }
+
+        public OpenPgpSignatureResult[] newArray(final int size) {
+            return new OpenPgpSignatureResult[size];
+        }
+    };
+
+    @Override
+    public String toString() {
+        String out = "\nstatus: " + status;
+        out += "\nprimaryUserId: " + primaryUserId;
+        out += "\nuserIds: " + userIds;
+        out += "\nsignatureOnly: " + signatureOnly;
+        out += "\nkeyId: " + OpenPgpUtils.convertKeyIdToHex(keyId);
+        return out;
+    }
+
+}
diff --git a/libs/openpgp-api-lib/src/org/openintents/openpgp/util/OpenPgpApi.java b/libs/openpgp-api-lib/src/org/openintents/openpgp/util/OpenPgpApi.java
new file mode 100644
index 00000000..3e18ab0c
--- /dev/null
+++ b/libs/openpgp-api-lib/src/org/openintents/openpgp/util/OpenPgpApi.java
@@ -0,0 +1,306 @@
+/*
+ * Copyright (C) 2014 Dominik Schürmann <dominik@dominikschuermann.de>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.openintents.openpgp.util;
+
+import android.annotation.TargetApi;
+import android.content.Context;
+import android.content.Intent;
+import android.os.AsyncTask;
+import android.os.Build;
+import android.os.ParcelFileDescriptor;
+import android.util.Log;
+
+import org.openintents.openpgp.IOpenPgpService;
+import org.openintents.openpgp.OpenPgpError;
+
+import java.io.InputStream;
+import java.io.OutputStream;
+
+public class OpenPgpApi {
+
+    public static final String TAG = "OpenPgp API";
+
+    public static final String SERVICE_INTENT = "org.openintents.openpgp.IOpenPgpService";
+
+    /**
+     * Version history
+     * ---------------
+     * <p/>
+     * 3:
+     * - first public stable version
+     * <p/>
+     * 4:
+     * - No changes to existing methods -> backward compatible
+     * - Introduction of ACTION_DECRYPT_METADATA, RESULT_METADATA, EXTRA_ORIGINAL_FILENAME, and OpenPgpMetadata parcel
+     * - Introduction of internal NFC extras: EXTRA_NFC_SIGNED_HASH, EXTRA_NFC_SIG_CREATION_TIMESTAMP
+     * 5:
+     * - OpenPgpSignatureResult: new consts SIGNATURE_KEY_REVOKED and SIGNATURE_KEY_EXPIRED
+     * - OpenPgpSignatureResult: ArrayList<String> userIds
+     */
+    public static final int API_VERSION = 5;
+
+    /**
+     * General extras
+     * --------------
+     *
+     * required extras:
+     * int           EXTRA_API_VERSION           (always required)
+     *
+     * returned extras:
+     * int           RESULT_CODE                 (RESULT_CODE_ERROR, RESULT_CODE_SUCCESS or RESULT_CODE_USER_INTERACTION_REQUIRED)
+     * OpenPgpError  RESULT_ERROR                (if RESULT_CODE == RESULT_CODE_ERROR)
+     * PendingIntent RESULT_INTENT               (if RESULT_CODE == RESULT_CODE_USER_INTERACTION_REQUIRED)
+     */
+
+    /**
+     * Sign only
+     * <p/>
+     * optional extras:
+     * boolean       EXTRA_REQUEST_ASCII_ARMOR   (request ascii armor for output)
+     * String        EXTRA_PASSPHRASE            (key passphrase)
+     */
+    public static final String ACTION_SIGN = "org.openintents.openpgp.action.SIGN";
+
+    /**
+     * Encrypt
+     * <p/>
+     * required extras:
+     * String[]      EXTRA_USER_IDS              (=emails of recipients, if more than one key has a user_id, a PendingIntent is returned via RESULT_INTENT)
+     * or
+     * long[]        EXTRA_KEY_IDS
+     * <p/>
+     * optional extras:
+     * boolean       EXTRA_REQUEST_ASCII_ARMOR   (request ascii armor for output)
+     * String        EXTRA_PASSPHRASE            (key passphrase)
+     * String        EXTRA_ORIGINAL_FILENAME     (original filename to be encrypted as metadata)
+     */
+    public static final String ACTION_ENCRYPT = "org.openintents.openpgp.action.ENCRYPT";
+
+    /**
+     * Sign and encrypt
+     * <p/>
+     * required extras:
+     * String[]      EXTRA_USER_IDS              (=emails of recipients, if more than one key has a user_id, a PendingIntent is returned via RESULT_INTENT)
+     * or
+     * long[]        EXTRA_KEY_IDS
+     * <p/>
+     * optional extras:
+     * boolean       EXTRA_REQUEST_ASCII_ARMOR   (request ascii armor for output)
+     * String        EXTRA_PASSPHRASE            (key passphrase)
+     * String        EXTRA_ORIGINAL_FILENAME     (original filename to be encrypted as metadata)
+     */
+    public static final String ACTION_SIGN_AND_ENCRYPT = "org.openintents.openpgp.action.SIGN_AND_ENCRYPT";
+
+    /**
+     * Decrypts and verifies given input stream. This methods handles encrypted-only, signed-and-encrypted,
+     * and also signed-only input.
+     * <p/>
+     * If OpenPgpSignatureResult.getStatus() == OpenPgpSignatureResult.SIGNATURE_KEY_MISSING
+     * in addition a PendingIntent is returned via RESULT_INTENT to download missing keys.
+     * <p/>
+     * optional extras:
+     * boolean       EXTRA_REQUEST_ASCII_ARMOR   (request ascii armor for output)
+     * <p/>
+     * returned extras:
+     * OpenPgpSignatureResult   RESULT_SIGNATURE
+     * OpenPgpDecryptMetadata   RESULT_METADATA
+     */
+    public static final String ACTION_DECRYPT_VERIFY = "org.openintents.openpgp.action.DECRYPT_VERIFY";
+
+    /**
+     * Decrypts the header of an encrypted file to retrieve metadata such as original filename.
+     * <p/>
+     * This does not decrypt the actual content of the file.
+     * <p/>
+     * returned extras:
+     * OpenPgpDecryptMetadata   RESULT_METADATA
+     */
+    public static final String ACTION_DECRYPT_METADATA = "org.openintents.openpgp.action.DECRYPT_METADATA";
+
+    /**
+     * Get key ids based on given user ids (=emails)
+     * <p/>
+     * required extras:
+     * String[]      EXTRA_USER_IDS
+     * <p/>
+     * returned extras:
+     * long[]        RESULT_KEY_IDS
+     */
+    public static final String ACTION_GET_KEY_IDS = "org.openintents.openpgp.action.GET_KEY_IDS";
+
+    /**
+     * This action returns RESULT_CODE_SUCCESS if the OpenPGP Provider already has the key
+     * corresponding to the given key id in its database.
+     * <p/>
+     * It returns RESULT_CODE_USER_INTERACTION_REQUIRED if the Provider does not have the key.
+     * The PendingIntent from RESULT_INTENT can be used to retrieve those from a keyserver.
+     * <p/>
+     * required extras:
+     * long        EXTRA_KEY_ID
+     */
+    public static final String ACTION_GET_KEY = "org.openintents.openpgp.action.GET_KEY";
+
+    /* Intent extras */
+    public static final String EXTRA_API_VERSION = "api_version";
+
+    public static final String EXTRA_ACCOUNT_NAME = "account_name";
+
+    // SIGN, ENCRYPT, SIGN_AND_ENCRYPT, DECRYPT_VERIFY
+    // request ASCII Armor for output
+    // OpenPGP Radix-64, 33 percent overhead compared to binary, see http://tools.ietf.org/html/rfc4880#page-53)
+    public static final String EXTRA_REQUEST_ASCII_ARMOR = "ascii_armor";
+
+    // ENCRYPT, SIGN_AND_ENCRYPT
+    public static final String EXTRA_USER_IDS = "user_ids";
+    public static final String EXTRA_KEY_IDS = "key_ids";
+    // optional extras:
+    public static final String EXTRA_PASSPHRASE = "passphrase";
+    public static final String EXTRA_ORIGINAL_FILENAME = "original_filename";
+
+    // internal NFC states
+    public static final String EXTRA_NFC_SIGNED_HASH = "nfc_signed_hash";
+    public static final String EXTRA_NFC_SIG_CREATION_TIMESTAMP = "nfc_sig_creation_timestamp";
+    public static final String EXTRA_NFC_DECRYPTED_SESSION_KEY = "nfc_decrypted_session_key";
+
+    // GET_KEY
+    public static final String EXTRA_KEY_ID = "key_id";
+    public static final String RESULT_KEY_IDS = "key_ids";
+
+    /* Service Intent returns */
+    public static final String RESULT_CODE = "result_code";
+
+    // get actual error object from RESULT_ERROR
+    public static final int RESULT_CODE_ERROR = 0;
+    // success!
+    public static final int RESULT_CODE_SUCCESS = 1;
+    // get PendingIntent from RESULT_INTENT, start PendingIntent with startIntentSenderForResult,
+    // and execute service method again in onActivityResult
+    public static final int RESULT_CODE_USER_INTERACTION_REQUIRED = 2;
+
+    public static final String RESULT_ERROR = "error";
+    public static final String RESULT_INTENT = "intent";
+
+    // DECRYPT_VERIFY
+    public static final String RESULT_SIGNATURE = "signature";
+    public static final String RESULT_METADATA = "metadata";
+
+    IOpenPgpService mService;
+    Context mContext;
+
+    public OpenPgpApi(Context context, IOpenPgpService service) {
+        this.mContext = context;
+        this.mService = service;
+    }
+
+    public interface IOpenPgpCallback {
+        void onReturn(final Intent result);
+    }
+
+    private class OpenPgpAsyncTask extends AsyncTask<Void, Integer, Intent> {
+        Intent data;
+        InputStream is;
+        OutputStream os;
+        IOpenPgpCallback callback;
+
+        private OpenPgpAsyncTask(Intent data, InputStream is, OutputStream os, IOpenPgpCallback callback) {
+            this.data = data;
+            this.is = is;
+            this.os = os;
+            this.callback = callback;
+        }
+
+        @Override
+        protected Intent doInBackground(Void... unused) {
+            return executeApi(data, is, os);
+        }
+
+        protected void onPostExecute(Intent result) {
+            callback.onReturn(result);
+        }
+
+    }
+
+    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
+    public void executeApiAsync(Intent data, InputStream is, OutputStream os, IOpenPgpCallback callback) {
+        OpenPgpAsyncTask task = new OpenPgpAsyncTask(data, is, os, callback);
+
+        // don't serialize async tasks!
+        // http://commonsware.com/blog/2012/04/20/asynctask-threading-regression-confirmed.html
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
+            task.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, (Void[]) null);
+        } else {
+            task.execute((Void[]) null);
+        }
+    }
+
+    public Intent executeApi(Intent data, InputStream is, OutputStream os) {
+        try {
+            data.putExtra(EXTRA_API_VERSION, OpenPgpApi.API_VERSION);
+
+            Intent result;
+
+            // pipe the input and output
+            ParcelFileDescriptor input = null;
+            if (is != null) {
+                input = ParcelFileDescriptorUtil.pipeFrom(is,
+                        new ParcelFileDescriptorUtil.IThreadListener() {
+
+                            @Override
+                            public void onThreadFinished(Thread thread) {
+                                //Log.d(OpenPgpApi.TAG, "Copy to service finished");
+                            }
+                        }
+                );
+            }
+            ParcelFileDescriptor output = null;
+            if (os != null) {
+                output = ParcelFileDescriptorUtil.pipeTo(os,
+                        new ParcelFileDescriptorUtil.IThreadListener() {
+
+                            @Override
+                            public void onThreadFinished(Thread thread) {
+                                //Log.d(OpenPgpApi.TAG, "Service finished writing!");
+                            }
+                        }
+                );
+            }
+
+            // blocks until result is ready
+            result = mService.execute(data, input, output);
+            // close() is required to halt the TransferThread
+            if (output != null) {
+                output.close();
+            }
+            // TODO: close input?
+
+            // set class loader to current context to allow unparcelling
+            // of OpenPgpError and OpenPgpSignatureResult
+            // http://stackoverflow.com/a/3806769
+            result.setExtrasClassLoader(mContext.getClassLoader());
+
+            return result;
+        } catch (Exception e) {
+            Log.e(OpenPgpApi.TAG, "Exception in executeApi call", e);
+            Intent result = new Intent();
+            result.putExtra(RESULT_CODE, RESULT_CODE_ERROR);
+            result.putExtra(RESULT_ERROR,
+                    new OpenPgpError(OpenPgpError.CLIENT_SIDE_ERROR, e.getMessage()));
+            return result;
+        }
+    }
+
+}
diff --git a/libs/openpgp-api-lib/src/org/openintents/openpgp/util/OpenPgpListPreference.java b/libs/openpgp-api-lib/src/org/openintents/openpgp/util/OpenPgpListPreference.java
new file mode 100644
index 00000000..cf586462
--- /dev/null
+++ b/libs/openpgp-api-lib/src/org/openintents/openpgp/util/OpenPgpListPreference.java
@@ -0,0 +1,257 @@
+/*
+ * Copyright (C) 2014 Dominik Schürmann <dominik@dominikschuermann.de>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.openintents.openpgp.util;
+
+import android.app.AlertDialog.Builder;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.content.Intent;
+import android.content.pm.ResolveInfo;
+import android.content.res.TypedArray;
+import android.graphics.drawable.Drawable;
+import android.net.Uri;
+import android.preference.DialogPreference;
+import android.util.AttributeSet;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ArrayAdapter;
+import android.widget.ListAdapter;
+import android.widget.TextView;
+import org.openintents.openpgp.R;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Does not extend ListPreference, but is very similar to it!
+ * http://grepcode.com/file_/repository.grepcode.com/java/ext/com.google.android/android/4.4_r1/android/preference/ListPreference.java/?v=source
+ */
+public class OpenPgpListPreference extends DialogPreference {
+    private static final String OPENKEYCHAIN_PACKAGE = "org.sufficientlysecure.keychain";
+    private static final String MARKET_INTENT_URI_BASE = "market://details?id=%s";
+    private static final Intent MARKET_INTENT = new Intent(Intent.ACTION_VIEW, Uri.parse(
+            String.format(MARKET_INTENT_URI_BASE, OPENKEYCHAIN_PACKAGE)));
+
+    private ArrayList<OpenPgpProviderEntry> mLegacyList = new ArrayList<OpenPgpProviderEntry>();
+    private ArrayList<OpenPgpProviderEntry> mList = new ArrayList<OpenPgpProviderEntry>();
+
+    private String mSelectedPackage;
+
+    public OpenPgpListPreference(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    public OpenPgpListPreference(Context context) {
+        this(context, null);
+    }
+
+    /**
+     * Public method to add new entries for legacy applications
+     *
+     * @param packageName
+     * @param simpleName
+     * @param icon
+     */
+    public void addLegacyProvider(int position, String packageName, String simpleName, Drawable icon) {
+        mLegacyList.add(position, new OpenPgpProviderEntry(packageName, simpleName, icon));
+    }
+
+    @Override
+    protected void onPrepareDialogBuilder(Builder builder) {
+        mList.clear();
+        
+        // add "none"-entry
+        mList.add(0, new OpenPgpProviderEntry("",
+                getContext().getString(R.string.openpgp_list_preference_none),
+                getContext().getResources().getDrawable(R.drawable.ic_action_cancel_launchersize)));
+        
+        // add all additional (legacy) providers
+        mList.addAll(mLegacyList);
+        
+        // search for OpenPGP providers...
+        ArrayList<OpenPgpProviderEntry> providerList = new ArrayList<OpenPgpProviderEntry>();
+        Intent intent = new Intent(OpenPgpApi.SERVICE_INTENT);
+        List<ResolveInfo> resInfo = getContext().getPackageManager().queryIntentServices(intent, 0);
+        if (!resInfo.isEmpty()) {
+            for (ResolveInfo resolveInfo : resInfo) {
+                if (resolveInfo.serviceInfo == null)
+                    continue;
+
+                String packageName = resolveInfo.serviceInfo.packageName;
+                String simpleName = String.valueOf(resolveInfo.serviceInfo.loadLabel(getContext()
+                        .getPackageManager()));
+                Drawable icon = resolveInfo.serviceInfo.loadIcon(getContext().getPackageManager());
+
+                providerList.add(new OpenPgpProviderEntry(packageName, simpleName, icon));
+            }
+        }
+
+        if (providerList.isEmpty()) {
+            // add install links if provider list is empty
+            resInfo = getContext().getPackageManager().queryIntentActivities
+                    (MARKET_INTENT, 0);
+            for (ResolveInfo resolveInfo : resInfo) {
+                Intent marketIntent = new Intent(MARKET_INTENT);
+                marketIntent.setPackage(resolveInfo.activityInfo.packageName);
+                Drawable icon = resolveInfo.activityInfo.loadIcon(getContext().getPackageManager());
+                String marketName = String.valueOf(resolveInfo.activityInfo.applicationInfo
+                        .loadLabel(getContext().getPackageManager()));
+                String simpleName = String.format(getContext().getString(R.string
+                        .openpgp_install_openkeychain_via), marketName);
+                mList.add(new OpenPgpProviderEntry(OPENKEYCHAIN_PACKAGE, simpleName,
+                        icon, marketIntent));
+            }
+        } else {
+            // add provider
+            mList.addAll(providerList);
+        }
+
+        // Init ArrayAdapter with OpenPGP Providers
+        ListAdapter adapter = new ArrayAdapter<OpenPgpProviderEntry>(getContext(),
+                android.R.layout.select_dialog_singlechoice, android.R.id.text1, mList) {
+            public View getView(int position, View convertView, ViewGroup parent) {
+                // User super class to create the View
+                View v = super.getView(position, convertView, parent);
+                TextView tv = (TextView) v.findViewById(android.R.id.text1);
+
+                // Put the image on the TextView
+                tv.setCompoundDrawablesWithIntrinsicBounds(mList.get(position).icon, null,
+                        null, null);
+
+                // Add margin between image and text (support various screen densities)
+                int dp10 = (int) (10 * getContext().getResources().getDisplayMetrics().density + 0.5f);
+                tv.setCompoundDrawablePadding(dp10);
+
+                return v;
+            }
+        };
+
+        builder.setSingleChoiceItems(adapter, getIndexOfProviderList(getValue()),
+                new DialogInterface.OnClickListener() {
+
+                    @Override
+                    public void onClick(DialogInterface dialog, int which) {
+                        OpenPgpProviderEntry entry = mList.get(which);
+
+                        if (entry.intent != null) {
+                            /*
+                             * Intents are called as activity
+                             *
+                             * Current approach is to assume the user installed the app.
+                             * If he does not, the selected package is not valid.
+                             *
+                             * However  applications should always consider this could happen,
+                             * as the user might remove the currently used OpenPGP app.
+                             */
+                            getContext().startActivity(entry.intent);
+                        }
+
+                        mSelectedPackage = entry.packageName;
+
+                        /*
+                         * Clicking on an item simulates the positive button click, and dismisses
+                         * the dialog.
+                         */
+                        OpenPgpListPreference.this.onClick(dialog, DialogInterface.BUTTON_POSITIVE);
+                        dialog.dismiss();
+                    }
+                });
+
+        /*
+         * The typical interaction for list-based dialogs is to have click-on-an-item dismiss the
+         * dialog instead of the user having to press 'Ok'.
+         */
+        builder.setPositiveButton(null, null);
+    }
+
+    @Override
+    protected void onDialogClosed(boolean positiveResult) {
+        super.onDialogClosed(positiveResult);
+
+        if (positiveResult && (mSelectedPackage != null)) {
+            if (callChangeListener(mSelectedPackage)) {
+                setValue(mSelectedPackage);
+            }
+        }
+    }
+
+    private int getIndexOfProviderList(String packageName) {
+        for (OpenPgpProviderEntry app : mList) {
+            if (app.packageName.equals(packageName)) {
+                return mList.indexOf(app);
+            }
+        }
+
+        return -1;
+    }
+
+    public void setValue(String packageName) {
+        mSelectedPackage = packageName;
+        persistString(packageName);
+    }
+
+    public String getValue() {
+        return mSelectedPackage;
+    }
+
+    public String getEntry() {
+        return getEntryByValue(mSelectedPackage);
+    }
+
+    @Override
+    protected Object onGetDefaultValue(TypedArray a, int index) {
+        return a.getString(index);
+    }
+
+    @Override
+    protected void onSetInitialValue(boolean restoreValue, Object defaultValue) {
+        setValue(restoreValue ? getPersistedString(mSelectedPackage) : (String) defaultValue);
+    }
+
+    public String getEntryByValue(String packageName) {
+        for (OpenPgpProviderEntry app : mList) {
+            if (app.packageName.equals(packageName)) {
+                return app.simpleName;
+            }
+        }
+
+        return null;
+    }
+
+    private static class OpenPgpProviderEntry {
+        private String packageName;
+        private String simpleName;
+        private Drawable icon;
+        private Intent intent;
+
+        public OpenPgpProviderEntry(String packageName, String simpleName, Drawable icon) {
+            this.packageName = packageName;
+            this.simpleName = simpleName;
+            this.icon = icon;
+        }
+
+        public OpenPgpProviderEntry(String packageName, String simpleName, Drawable icon, Intent intent) {
+            this(packageName, simpleName, icon);
+            this.intent = intent;
+        }
+
+        @Override
+        public String toString() {
+            return simpleName;
+        }
+    }
+}
diff --git a/libs/openpgp-api-lib/src/org/openintents/openpgp/util/OpenPgpServiceConnection.java b/libs/openpgp-api-lib/src/org/openintents/openpgp/util/OpenPgpServiceConnection.java
new file mode 100644
index 00000000..15096d9e
--- /dev/null
+++ b/libs/openpgp-api-lib/src/org/openintents/openpgp/util/OpenPgpServiceConnection.java
@@ -0,0 +1,124 @@
+/*
+ * Copyright (C) 2014 Dominik Schürmann <dominik@dominikschuermann.de>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.openintents.openpgp.util;
+
+import android.content.ComponentName;
+import android.content.Context;
+import android.content.Intent;
+import android.content.ServiceConnection;
+import android.os.IBinder;
+
+import org.openintents.openpgp.IOpenPgpService;
+
+public class OpenPgpServiceConnection {
+
+    // callback interface
+    public interface OnBound {
+        public void onBound(IOpenPgpService service);
+
+        public void onError(Exception e);
+    }
+
+    private Context mApplicationContext;
+
+    private IOpenPgpService mService;
+    private String mProviderPackageName;
+
+    private OnBound mOnBoundListener;
+
+    /**
+     * Create new connection
+     *
+     * @param context
+     * @param providerPackageName specify package name of OpenPGP provider,
+     *                            e.g., "org.sufficientlysecure.keychain"
+     */
+    public OpenPgpServiceConnection(Context context, String providerPackageName) {
+        this.mApplicationContext = context.getApplicationContext();
+        this.mProviderPackageName = providerPackageName;
+    }
+
+    /**
+     * Create new connection with callback
+     *
+     * @param context
+     * @param providerPackageName specify package name of OpenPGP provider,
+     *                            e.g., "org.sufficientlysecure.keychain"
+     * @param onBoundListener     callback, executed when connection to service has been established
+     */
+    public OpenPgpServiceConnection(Context context, String providerPackageName,
+                                    OnBound onBoundListener) {
+        this(context, providerPackageName);
+        this.mOnBoundListener = onBoundListener;
+    }
+
+    public IOpenPgpService getService() {
+        return mService;
+    }
+
+    public boolean isBound() {
+        return (mService != null);
+    }
+
+    private ServiceConnection mServiceConnection = new ServiceConnection() {
+        public void onServiceConnected(ComponentName name, IBinder service) {
+            mService = IOpenPgpService.Stub.asInterface(service);
+            if (mOnBoundListener != null) {
+                mOnBoundListener.onBound(mService);
+            }
+        }
+
+        public void onServiceDisconnected(ComponentName name) {
+            mService = null;
+        }
+    };
+
+    /**
+     * If not already bound, bind to service!
+     *
+     * @return
+     */
+    public void bindToService() {
+        // if not already bound...
+        if (mService == null) {
+            try {
+                Intent serviceIntent = new Intent(OpenPgpApi.SERVICE_INTENT);
+                // NOTE: setPackage is very important to restrict the intent to this provider only!
+                serviceIntent.setPackage(mProviderPackageName);
+                boolean connect = mApplicationContext.bindService(serviceIntent, mServiceConnection,
+                        Context.BIND_AUTO_CREATE);
+                if (!connect) {
+                    throw new Exception("bindService() returned false!");
+                }
+            } catch (Exception e) {
+                if (mOnBoundListener != null) {
+                    mOnBoundListener.onError(e);
+                }
+            }
+        } else {
+            // already bound, but also inform client about it with callback
+            if (mOnBoundListener != null) {
+                mOnBoundListener.onBound(mService);
+            }
+        }
+    }
+
+    public void unbindFromService() {
+        mApplicationContext.unbindService(mServiceConnection);
+    }
+
+}
diff --git a/libs/openpgp-api-lib/src/org/openintents/openpgp/util/OpenPgpUtils.java b/libs/openpgp-api-lib/src/org/openintents/openpgp/util/OpenPgpUtils.java
new file mode 100644
index 00000000..416b2841
--- /dev/null
+++ b/libs/openpgp-api-lib/src/org/openintents/openpgp/util/OpenPgpUtils.java
@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2014 Dominik Schürmann <dominik@dominikschuermann.de>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.openintents.openpgp.util;
+
+import java.util.List;
+import java.util.Locale;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import android.content.Context;
+import android.content.Intent;
+import android.content.pm.ResolveInfo;
+
+public class OpenPgpUtils {
+
+    public static final Pattern PGP_MESSAGE = Pattern.compile(
+            ".*?(-----BEGIN PGP MESSAGE-----.*?-----END PGP MESSAGE-----).*",
+            Pattern.DOTALL);
+
+    public static final Pattern PGP_SIGNED_MESSAGE = Pattern.compile(
+            ".*?(-----BEGIN PGP SIGNED MESSAGE-----.*?-----BEGIN PGP SIGNATURE-----.*?-----END PGP SIGNATURE-----).*",
+            Pattern.DOTALL);
+
+    public static final int PARSE_RESULT_NO_PGP = -1;
+    public static final int PARSE_RESULT_MESSAGE = 0;
+    public static final int PARSE_RESULT_SIGNED_MESSAGE = 1;
+
+    public static int parseMessage(String message) {
+        Matcher matcherSigned = PGP_SIGNED_MESSAGE.matcher(message);
+        Matcher matcherMessage = PGP_MESSAGE.matcher(message);
+
+        if (matcherMessage.matches()) {
+            return PARSE_RESULT_MESSAGE;
+        } else if (matcherSigned.matches()) {
+            return PARSE_RESULT_SIGNED_MESSAGE;
+        } else {
+            return PARSE_RESULT_NO_PGP;
+        }
+    }
+
+    public static boolean isAvailable(Context context) {
+        Intent intent = new Intent(OpenPgpApi.SERVICE_INTENT);
+        List<ResolveInfo> resInfo = context.getPackageManager().queryIntentServices(intent, 0);
+        if (!resInfo.isEmpty()) {
+            return true;
+        } else {
+            return false;
+        }
+    }
+
+    public static String convertKeyIdToHex(long keyId) {
+        return "0x" + convertKeyIdToHex32bit(keyId >> 32) + convertKeyIdToHex32bit(keyId);
+    }
+
+    private static String convertKeyIdToHex32bit(long keyId) {
+        String hexString = Long.toHexString(keyId & 0xffffffffL).toLowerCase(Locale.ENGLISH);
+        while (hexString.length() < 8) {
+            hexString = "0" + hexString;
+        }
+        return hexString;
+    }
+}
diff --git a/libs/openpgp-api-lib/src/org/openintents/openpgp/util/ParcelFileDescriptorUtil.java b/libs/openpgp-api-lib/src/org/openintents/openpgp/util/ParcelFileDescriptorUtil.java
new file mode 100644
index 00000000..4fd4b39a
--- /dev/null
+++ b/libs/openpgp-api-lib/src/org/openintents/openpgp/util/ParcelFileDescriptorUtil.java
@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2014 Dominik Schürmann <dominik@dominikschuermann.de>
+ *               2013 Florian Schmaus <flo@geekplace.eu>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.openintents.openpgp.util;
+
+import android.os.ParcelFileDescriptor;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+/**
+ * Partially based on <a href="http://stackoverflow.com/questions/18212152/">Stackoverflow: Transfer InputStream to another Service (across process boundaries)</a>
+ **/
+public class ParcelFileDescriptorUtil {
+
+    public interface IThreadListener {
+        void onThreadFinished(final Thread thread);
+    }
+
+    public static ParcelFileDescriptor pipeFrom(InputStream inputStream, IThreadListener listener)
+            throws IOException {
+        ParcelFileDescriptor[] pipe = ParcelFileDescriptor.createPipe();
+        ParcelFileDescriptor readSide = pipe[0];
+        ParcelFileDescriptor writeSide = pipe[1];
+
+        // start the transfer thread
+        new TransferThread(inputStream, new ParcelFileDescriptor.AutoCloseOutputStream(writeSide),
+                listener)
+                .start();
+
+        return readSide;
+    }
+
+    public static ParcelFileDescriptor pipeTo(OutputStream outputStream, IThreadListener listener)
+            throws IOException {
+        ParcelFileDescriptor[] pipe = ParcelFileDescriptor.createPipe();
+        ParcelFileDescriptor readSide = pipe[0];
+        ParcelFileDescriptor writeSide = pipe[1];
+
+        // start the transfer thread
+        new TransferThread(new ParcelFileDescriptor.AutoCloseInputStream(readSide), outputStream,
+                listener)
+                .start();
+
+        return writeSide;
+    }
+
+    static class TransferThread extends Thread {
+        final InputStream mIn;
+        final OutputStream mOut;
+        final IThreadListener mListener;
+
+        TransferThread(InputStream in, OutputStream out, IThreadListener listener) {
+            super("ParcelFileDescriptor Transfer Thread");
+            mIn = in;
+            mOut = out;
+            mListener = listener;
+            setDaemon(true);
+        }
+
+        @Override
+        public void run() {
+            byte[] buf = new byte[1024];
+            int len;
+
+            try {
+                while ((len = mIn.read(buf)) > 0) {
+                    mOut.write(buf, 0, len);
+                }
+                mOut.flush(); // just to be safe
+            } catch (IOException e) {
+                //Log.e(OpenPgpApi.TAG, "TransferThread" + getId() + ": writing failed", e);
+            } finally {
+                try {
+                    mIn.close();
+                } catch (IOException e) {
+                    //Log.e(OpenPgpApi.TAG, "TransferThread" + getId(), e);
+                }
+                try {
+                    mOut.close();
+                } catch (IOException e) {
+                    //Log.e(OpenPgpApi.TAG, "TransferThread" + getId(), e);
+                }
+            }
+            if (mListener != null) {
+                //Log.d(OpenPgpApi.TAG, "TransferThread " + getId() + " finished!");
+                mListener.onThreadFinished(this);
+            }
+        }
+    }
+}