In some countries where internet connectivity isn't that good, it makes the installation of apps straight from the Google Play Store "iffy." As a result, Android owners share APKs offline as a way to install apps on their devices. The problem doing this is that these apps could be contagious since they are not equipped with Google Play security, even if the original came from the Google Play Store. They also can't receive updates. But soon, Google will add a small amount of security metadata on top of APKs that will allow shared apps to have the same security features and update capabilities as those installed straight from the Google Play Store.
Google will be able to verify these apps even when the device they are installed on is offline. Once the device is back online, these shared apps can be added to a user's Google Play library and receive regular updates. Google says that this will not only give users more confidence about using these shared apps, it will result in an off-line distribution network that is authorized by Google Play.
To get this done, the maximum size of APKs will be increased slightly to cover the small addition of security metadata. Users will benefit from the increased security for shared apps, and more will be able to keep their apps up-to-date. Google says that developers will get new distribution opportunities and won't even have to make any changes to their apps to implement this program.