  In the realm of mobile security, where OS-based protections have proven
insufficient against robust attackers, Trusted Execution Environments (TEEs)
have emerged as a hardware-based security technology. Despite the industry's
persistence in advancing TEE technology, the impact on end users and developers
remains largely unexplored. This study addresses this gap by conducting a
large-scale analysis of TEE utilization in Android applications, focusing on
the key areas of cryptography, digital rights management, biometric
authentication, and secure dialogs.
  To facilitate our extensive analysis, we introduce Mobsec Analytika, a
framework tailored for large-scale app examinations, which we make available to
the research community. Through the analysis of 170,550 popular Android apps,
our analysis illuminates the implementation of TEE-related features and their
contextual usage.
  Our findings reveal that TEE features are predominantly utilized indirectly
through third-party libraries, with only 6.7% of apps directly invoking the
APIs. Moreover, the study reveals the underutilization of the recent TEE-based
UI feature Protected Confirmation.
