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 Ant

1. Have Android SDK "tools" directory in your PATH (http://developer.android.com/sdk/index.html)
2. Change to "OpenPGP-Kechain" directory with cd OpenPGP-Kechain
3. Execute android update project -p . and android update project -p android-libs/ActionBarSherlock
4. Execute ant debug

Build with Eclipse

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

Libraries

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

• ActionBarSherlock to provide an ActionBar for Android < 3.0
• 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.

see http://rtyley.github.com/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

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