title: Secure/protected content distribution for Android app
body: <p>Here is my scenario: I need to distribute optional content packages for an Android application in a secure/protected way, i.e. prevent download of the content from outside the application. The content consists of zipped SQLite database creation files with sizes up to 4 Megabytes. The packages will be updated 4 times a year. I have currently about 1000 active installations. This means at peak times traffic for downloading the content package updates could yield in about 4 GB per day. The installation base of the app grows  by roughly 100 users per day.</p>
  
  <p>Based on the scenario I wonder how to solve the following issues:</p>
  
  <ol>
  <li><p>What would be the best way to distribute the content? HTTPS transport? What would be a recommended way to do authentication (e.g. passwords, certificates)? Should I use password protected Zip files instead?</p></li>
  <li><p>Which infrastructure should be used for content delivery that fits the following criteria: </p>
  
  <ul>
  <li>support of the protection mechanism from 1) out of the box</li>
  <li>easy to setup and maintain</li>
  <li>scalable and download nodes in Europe and the US</li>
  <li>relatively inexpensive (not more than 30$ per month). Ideally pay-as-you-go bandwidth.</li>
  </ul></li>
  </ol>
  
  <p>I was considering CDNs like SoftLayer, Amazon CloudFront, etc. Any recommendations?</p>