OpenPGP Keychain (for Android)

OpenPGP Keychain is an OpenPGP implementation for Android. The development began as a fork of Android Privacy Guard (APG).

see http://sufficientlysecure.org/keychain

Build

Build with Gradle

1. Have Android SDK "tools", "platform-tools", and "build-tools" directories in your PATH (http://developer.android.com/sdk/index.html)
2. Export ANDROID_HOME pointing to your Android SDK
3. Install gradle
4. Execute gradle wrapper (http://www.gradle.org/docs/current/userguide/gradle_wrapper.html)
5. Execute ./gradlew build

Build with Ant

1. Have Android SDK "tools" directory in your PATH (http://developer.android.com/sdk/index.html)
2. Execute android update project -p OpenPGP-Keychain
3. Execute android update project -p libraries/ActionBarSherlock
4. Execute android update project -p libraries/HtmlTextView
5. Execute cd OpenPGP-Kechain, ant debug

Contribute

Fork OpenPGP Keychain and do a merge request. I will merge your changes back into the main project.

Development with Eclipse

Android Studio is currently not supported or recommended!

1. File -> Import -> Android -> Existing Android Code Into Workspace, choose "libraries/ActionBarSherlock"
2. File -> Import -> Android -> Existing Android Code Into Workspace, choose "libraries/HtmlTextView"
3. File -> Import -> Android -> Existing Android Code Into Workspace, choose "OpenPGP-Keychain"
4. OpenPGP-Kechain can now be build

Keychain API

API without registering the app

Intent Actions

All Intents require user interaction, e.g. encryption is not done automatically (e.g. click a button in a dialog to actually encrypt!). To do automatic encryption/decryption/sign/verify use the Remote Serive API.

Android Intent actions provided by OpenPGP Keychain:

• android.intent.action.VIEW connected to .gpg and .asc files: Import Key and Decrypt
• android.intent.action.SEND connected to all mime types (text/plain and every binary data like files and images): Encrypt and Decrypt

OpenPGP Keychain specific Intent actions:

• org.sufficientlysecure.keychain.action.ENCRYPT
  • To encrypt text use extra text (type: String)
  • To encrypt bytes use extra data (type: byte[])
  • Enable ASCII Armor (encoding to Radix-64, 33% overhead) by adding the extra ascii_armor with value true
• org.sufficientlysecure.keychain.action.ENCRYPT_FILE
  • Include data Uri (intent.setData()) pointing to a file or content provider
• org.sufficientlysecure.keychain.action.DECRYPT
  • To decrypt text use extra text (type: String)
  • To decrypt bytes use extra data (type: byte[])
• org.sufficientlysecure.keychain.action.DECRYPT_FILE
  • Include data Uri (intent.setData()) pointing to a file or content provider
• org.sufficientlysecure.keychain.action.IMPORT_KEY
  • Extras: key_bytes (type: byte[])
  • or Uri in data with file schema
• org.sufficientlysecure.keychain.action.IMPORT_KEY_FROM_QR_CODE
  • without extras starts Barcode Scanner to get QR Code

Remote Service API

To do asyncronous fast encryption/decryption/sign/verify operations bind to the remote service. The API Demo contains all required AIDL files and a demo activity.

Test API

Try out the new OpenPGP Keychain API:

Keychain: https://play.google.com/stor/apps/details?id=org.sufficientlysecure.keychain

API Demo: https://play.google.com/stor/apps/details?id=org.sufficientlysecure.keychain.demo

Design

As discussed previously I now present my new Crypto API that I propose for integration into k9mail. All apps wanting to use this generic API just need to include the AIDL files and connect to the service. Other crypto apps can implement a service based on this AIDL definition.

The API is designed to be as easy as possible to use by apps like k9mail. The service definition defines sign/encrypt/signAndEncrypt/decryptAndVerify [1].

As can be seen the apps themselves never need handle key ids directly. Only user ids (emails) are used to define recipients. If more than one pub key exists for an email, OpenPGP Keychain will handle the problem by showing a selection screen.

Also app devs never need to fiddle with private keys. On first operation, OpenPGP Keychain shows an activity to allow or disallow access, while also allowing to choose the private key used for this app. Please try the Demo app out to see how it works [4].

Integration

The API is defined as AIDL interfaces in org.openintents.crypto packge [2]. All files from [2] needs to be included in the project.

Using the CryptoServiceConnection.java [3] you can choose to which crypto provider you want to connect (other pgp apps can implement the interfaces). They can be queried as shown in the demo app (see [3] how to query). If other crypto apps implement the service, no additional code is required in k9mail per provider. See [3] for a complete example for integration.

ToDos

• error handling needs improvements
• signature results needs improvements (should also contain email address)
• Integration in k9mail

[1] https://github.com/dschuermann/openpgp-keychain/blob/master/OpenPGP-Keychain-API-Demo/src/org/openintents/crypto/ICryptoService.aidl

[2] https://github.com/dschuermann/openpgp-keychain/tree/master/OpenPGP-Keychain-API-Demo/src/org/openintents/crypto

[3] https://github.com/dschuermann/openpgp-keychain/blob/master/OpenPGP-Keychain-API-Demo/src/org/openintents/crypto/CryptoServiceConnection.java

[3] https://github.com/dschuermann/openpgp-keychain/blob/master/OpenPGP-Keychain-API-Demo/src/org/sufficientlysecure/keychain/demo/CryptoProviderDemoActivity.java

[4] https://play.google.com/stor/apps/details?id=org.sufficientlysecure.keychain.demo

Libraries

All JAR-Libraries are provided in this repository under "libs", all Android Library projects are under "libraries".

• ActionBarSherlock to provide an ActionBar for Android < 3.0
• HtmlTextView for non-crashing TextViews with HTML content
• forked Spongy Castle Crypto Lib (Android version of Bouncy Castle)
• barcodescanner-android-integration-supportv4.jar: Barcode Scanner Integration

Build Barcode Scanner Integration

1. Checkout their SVN (see http://code.google.com/p/zxing/source/checkout)
2. Change android-home variable in "build.properties" in the main directory to point to your Android SDK
3. Change directory to android-integration
4. Build using ant build
5. We use "android-integration-supportv4.jar"

On error see: http://code.google.com/p/zxing/issues/detail?id=1207

Build Spongy Castle

Spongy Castle is the stock Bouncy Castle libraries with a couple of small changes to make it work on Android. OpenPGP-Keychain uses a forked version with some small changes to improve key import speed. These changes have been sent to Bouncy Castle, and Spongy Castle will be used again when they have filtered down.

see

• http://rtyley.github.com/spongycastle/
• https://github.com/ashh87/spongycastle

Notes

Eclipse: "GC overhead limit exceeded"

If you have problems starting OpenPGP Kechain from Eclipse, consider increasing the memory limits in eclipse.ini. See http://docs.oseems.com/general/application/eclipse/fix-gc-overhead-limit-exceeded for more information.

Generate pressed dashboard icons

1. Open svg file in Inkscape
2. Extensions -> Color -> darker (2 times!)

Coding Style

Code

• Indentation: 4 spaces, no tabs
• Maximum line width for code and comments: 100
• Opening braces don't go on their own line
• Field names: Non-public, non-static fields start with m.
• Acronyms are words: Treat acronyms as words in names, yielding !XmlHttpRequest, getUrl(), etc.

See http://source.android.com/source/code-style.html

XML Eclipse Settings

• XML Maximum line width 999
• XML: Split multiple attributes each on a new line (Eclipse: Properties -> XML -> XML Files -> Editor)
• XML: Indent using spaces with Indention size 4 (Eclipse: Properties -> XML -> XML Files -> Editor)

See http://www.androidpolice.com/2009/11/04/auto-formatting-android-xml-files-with-eclipse/

Licenses

OpenPGP Kechain is licensed under GPLv3+. Some parts (older parts and some libraries are Apache License v2, MIT X11 License)

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.

Libraries

• SpongyCastle
  https://github.com/rtyley/spongycastle
  MIT X11 License

• ActionBarSherlock
  http://actionbarsherlock.com/
  Apache License v2

• HtmlTextView
  https://github.com/dschuermann/html-textview
  Apache License v2

• ZXing QRCode Integration
  http://code.google.com/p/zxing/
  Apache License v2

Images

• icon.svg
  modified version of kgpg_key2_kopete.svgz

• dashboard_manage_keys.svg, dashboard_my_keys.svg, key.svg
  http://rrze-icon-set.berlios.de/
  Creative Commons Attribution Share-Alike licence 3.0

• dashboard_decrypt.svg, dashboard_encrypt.svg, dashboard_help.svg
  http://tango.freedesktop.org/
  Public Domain

• dashboard_scan_qrcode.svg
  New creation for OpenPGP Kechain
  Apache License v2