Workaround for lack of NPAPI support in Google Chrome

[kylehuff]

In order to continue to supporting Google Chrome after their discontinuation of NPAPI, WebPG will need to use "Native Messaging".

Native Messaging is a mechanism whereby request/response messsages are sent/collected using chrome.runtime.sendNativeMessage or via a native messaging port.

The underlying WebPG binary component has been designed to support Native Messaging, however, it requires that a manifest file (and registry key in Windows) be installed on the host system along with a binary. An installer will be necessary in order to accomplish this.

The contents of said file are as follows -

{
   "name": "org.webpg.nativeHost",
   "description": "WebPG Native Messaging Host",
   "path": "C:\\Users\\{USER}\\AppData\\WebPG\\webpg_message_host.exe",
   "type": "stdio",
   "allowed_origins": [
     "chrome-extension://<EXTENSION_ID>" // Production extension ID
     "chrome-extension://<EXTENSION_ID>" // Development extension ID
     "chrome-extension://<EXTENSION_ID>" // Offline extension ID
  ]
}

File Location (Proposed):

• Linux: ~/.config/google-chrome/NativeMessagingHosts/org.webpg.nativeHost.json
• OSX: ~/Library/Application Support/Google/Chrome/NativeMessagingHosts/org.webpg.nativeHost.json
• Windows: C:\Users\{USER}\AppData\WebPG\nativeHost.json

Additional install items

• Linux: ~/bin/webpg/webpg_message_host
• OSX: ~/bin/webpg/webpg_message_host (?? better location in OSX)
• Windows
  • C:\Users{USER}\AppData\WebPG\webpg_message_host.exe
  • C:\Users{USER}\AppData\WebPG\libassuan-0.dll
  • C:\Users{USER}\AppData\WebPG\libgpg-error-0.dll
  • C:\Users{USER}\AppData\WebPG\libgpgme-11.dll
  • Registry key: HKEY_CURRENT_USER\SOFTWARE\Google\Chrome\NativeMessagingHosts\org.webpg.nativeHost
    • Value: C:\Users\{USER}\AppData\WebPG\nativeHost.json

Points of discussion -

• File locations
• binary naming convention
• Should the release version be included in the path or binary naming scheme?
• More?

Objectives -

• Easy to install
• Should be easy to uninstall
• Aware of system vs. user installation
• As least "hokey" as possible.

Ancillary items -

• Extension needs to be modified to in order to communicate with the host (assigned: kylehuff)
• Need to hook into installation events of extension to catch uninstall
• PGPMime methods need to be moved from webpg-npapi to libwebpg (completed with kylehuff/libwebpg@e31f59c)
• Others?

References -

• https://developer.chrome.com/extensions/messaging#native-messaging-host

Persons tagged in this issue -

• @kylehuff
• @darkpixel

[dhyannataraj]

Hi!
I have a dumb question:
What should I build to get webpg_message_host executable?
I did not find any unswer.
Or it is just a concept with no real executable available?

[dhyannataraj]

Oh, I found https://webpg.org/download/webpg-native-host/archive/ installers, but not source code... I do not like to download binaries... Is code avalable?

[dhyannataraj]

I found an answer. It took me a while (I was ready to write native host of my own)
webpg-native-host is a part of libwebpg project (surprise!)
once you build it, you get webpg executable that can work in native host mode.

[deed02392]

Should the release version be included in the path or binary naming scheme?

I think not. Installers can determine installed version and deal with accordingly. Users can inspect binary attributes/properties to determine version numbers (which will probably be more precise anyway). Besides, cannot think of a good use case for exposing the version number in path or filename, and doing so increases risk of mistakes being made when installing, updating or removing files.