OpenPGP Keychain (for Android)

OpenPGP Keychain is a EXPERIMENTAL fork of Android Privacy Guard (APG)

Contribute

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

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 assemble

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 and android update project -p libraries/ActionBarSherlock
3. Execute cd OpenPGP-Kechain, ant debug

Build with Eclipse

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

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
• forked Spongy Castle Crypto Lib (Android version of Bouncy Castle)
• android-support-v4.jar: Compatibility Lib
• 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!)

Security Model

Basic goals

• Intents without permissions should only work based on user interaction (e.g. click a button in a dialog)

Android primitives to exchange data: Intent, Intent with return values, Send (also an Intent), Content Provider, AIDL

Possible Permissions

• ACCESS_API: Encrypt/Sign/Decrypt/Create keys without user interaction (intents, remote service), Read key information (not the actual keys)(content provider)
• ACCESS_KEYS: get and import actual public and secret keys (remote service)

Without Permissions

Intents

All Intents start with org.sufficientlysecure.keychain.action.

• 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
• IMPORT
• IMPORT_FROM_FILE
• IMPORT_FROM_QR_CODE
• IMPORT_FROM_NFC
• SHARE_KEYRING
• SHARE_KEYRING_WITH_QR_CODE
• SHARE_KEYRING_WITH_NFC
• EDIT_KEYRING
• SELECT_PUBLIC_KEYRINGS
• SELECT_SECRET_KEYRING
• ENCRYPT
• ENCRYPT_FILE
• DECRYPT
• DECRYPT_FILE

With permission ACCESS_API

Intents

• CREATE_KEYRING
• ENCRYPT_AND_RETURN
• ENCRYPT_STREAM_AND_RETURN
• GENERATE_SIGNATURE_AND_RETURN
• DECRYPT_AND_RETURN
• DECRYPT_STREAM_AND_RETURN

Broadcast Receiver

On change of database the following broadcast is send.

• DATABASE_CHANGE

Content Provider

• The whole content provider requires a permission (only read)
• Don't give out blobs (keys can be accessed by ACCESS_KEYS via remote service)
• Make an internal and external content provider (or pathes with )
• Look at android:grantUriPermissions especially for ApgServiceBlobProvider
• Only give out android:readPermission

ApgApiService (Remote Service)

AIDL service

With permission ACCESS_KEYS

ApgKeyService (Remote Service)

AIDL service to access actual private keyring objects

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 Apache License v2.

Libraries

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

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

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

• HTMLCleaner
  http://htmlcleaner.sourceforge.net/
  BSD License

• HtmlSpanner
  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