  Privacy concerns have long been expressed around smart devices, and the
concerns around Android apps have been studied by many past works. Over the
past 10 years, we have crawled and scraped data for almost 1.9 million apps,
and also stored the APKs for 135,536 of them. In this paper, we examine the
trends in how Android apps have changed over time with respect to privacy and
look at it from two perspectives: (1) how privacy behavior in apps have changed
as they are updated over time, (2) how these changes can be accounted for when
comparing third-party libraries and the app's own internals. To study this, we
examine the adoption of HTTPS, whether apps scan the device for other installed
apps, the use of permissions for privacy-sensitive data, and the use of unique
identifiers. We find that privacy-related behavior has improved with time as
apps continue to receive updates, and that the third-party libraries used by
apps are responsible for more issues with privacy. However, we observe that in
the current state of Android apps, there has not been enough of an improvement
in terms of privacy and many issues still need to be addressed.
