Android Protected Confirmation is deprecated due to the high
support/maintenance cost for Android device makers and low adoption rate
among app developers. APC requires Android device makers to have a
substantial amount of device-specific UI code running in the trusted
execution environment. That has proven to be expensive to maintain and
non-scalable, as there cannot be a single implementations device makers
can share or use as a reference. Additionally, app developers have not
adopted this feature, as the Android platform offers other mechanisms
for authentication a user's intent. These mechanisms, such as
authentication-bound Keystore keys, are less secure than Trusted UI, but
are more wide-spread. While we explore alternatives to APC that are
viable to the device makers ecosystem, we sunset the APC API.
Bug: 313856313
Test: atest keystore2_test && atest CtsKeystoreTestCases
Change-Id: If065697ed13e3de706b8dde5cc5e2b6018592018
07fec0ff0c