I’m posting this little snippet up because I spent ages trying to work out how to do this, and thought that other googlers might benefit from this. I’ve got an Android application that stores some of its information on the SDCard which has some commercial value, and we don’t want our competitors simply walking away with the information. The security doesn’t need to be too tight, so I’m happy to have a password based encryption scheme which has the password in the code of the application.