Spongy Castle aims to be a full replacement for the crippled versions of the Bouncy Castle cryptographic libraries which ship with Android. You can read more about the project here:
https://github.com/rtyley/spongycastle#readme
This demo, spongycastle-eclipse, is just the simplest possible example of how to use Spongy Castle within an Eclipse project - it's not meant to be an interesting app!
I find setting up Spongy Castle in Eclipse pretty simple, but I might be making some assumptions that are worth documenting... the spongycastle-eclipse demo app was prompted by a question on StackOverflow:
http://stackoverflow.com/questions/6898801/how-to-include-the-spongy-castle-jar-in-android/7112272
