OnionKit for Android


This is an Android Library Project that provides multiple means to improve network security in mobile applications. The “Onion” name refers to not only the Onion Routing concept used by Tor (which provides anonymity and resistance to traffic surveillance), but also the idea of multiple layers of security that any application should utilize.

More specifically this library provides:

  1. StrongTrustManager: a robust implementation of an TLS/SSL certificate verifier, that can be customized with any set of certificate authorities
  2. Proxied Connection Support: HTTP and SOCKS proxy connection support for HTTP and HTTP/S traffic through specific configuration of the Apache HTTPClient library
  3. OrbotHelper: a utility class to support application integration with Orbot: Tor for Android. Check if its installed, running, etc.

IT MUST BE NOTED, that you can use this library without using Orbot/Tor, but obviously we think using strong TLS/SSL connections over Tor is just about the best thing in the world.



We have implemented a TrustManager for SSL Certificate verification that we believe is better than the default one provided by Android. For app developers, it provides for a consistent implementation of TLS/SSL verification and trust across various versions and devices.

It supports full chain verification, limited pinning, and a custom cacerts store based on the Debian set of certs. By providing our own cacert store, we can be assured that certificates are being validated against a known set of trusted Roots, and not compromised, expired or other non-desireable entities.

Developers can create their own CACert store using the information provided by our CACertMan project:https://github.com/guardianproject/cacert

It can be used in combination with the MemorizingTrustManager, to support user prompted override for non-validating certificates.

Proxied Connections (aka Orlib)

Once Orbot connects successfully to the Tor network, it offers two proxy servers running on localhost that applications can route their traffic through.

HTTP Proxy: localhost:8118 SOCKS 45 Proxy: localhost:9050

The sample project shows the basics of how to use this library to open sockets and make HTTP requests via the SOCKS and HTTP proxies available from Orbot The standard Apache HTTPClient libraries provide calls to setup proxying. This sample code demonstrates that. All applications using the SOCKS proxy should not resolve their DNS locally, and instead should pass the hostnames through the SOCKS proxy.

Orbot Helper

Provides simple helper to check if Orbot (Tor for Android) is installed, and whether it is currently running or not. Allows your app to request Orbot to start (user is prompted whether to start or not). Finally, it can show a user prompt to install Orbot, either from Google Play, or via direct APK download from torproject.org or the guardianproject.info site.

For apps with on-device servers, it can also assists in requesting a Tor Hidden Service from Orbot, and discovering the assigned .ONION address.