I thought this was used by Chromecast, although it exists in the cast private API also, so maybe it is only used there now? I don't see any internal references to it.

We should consider removing the Shill code as well if it is unused:
https://cs.chromium.org/chromium/src/chromeos/dbus/shill_manager_client.cc?q=VerifyAndEncryptCredentials&sq=package:chromium&dr=CSs&l=176

It was intended for Chromecast - I remember that there were plans to use this method to prepopulate network credentials during setup, but afaik that feature never actually got implemented.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1dc289654d394f910954978aeab08eb6d2997f32

commit 1dc289654d394f910954978aeab08eb6d2997f32
Author: Toni Barzic <tbarzic@google.com>
Date: Wed Oct 17 18:53:03 2018

Remove Chromecast verification methods from shill client

These are not used anymore (the verification is separately implemented
in Chrome).

BUG=846971

Change-Id: Id96f59850f2e56aeb766c34433b5c8a86a72cf4a
Reviewed-on: https://chromium-review.googlesource.com/c/1283484
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: Toni Baržić <tbarzic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600500}
[modify] https://crrev.com/1dc289654d394f910954978aeab08eb6d2997f32/chromeos/dbus/fake_shill_manager_client.cc
[modify] https://crrev.com/1dc289654d394f910954978aeab08eb6d2997f32/chromeos/dbus/fake_shill_manager_client.h
[modify] https://crrev.com/1dc289654d394f910954978aeab08eb6d2997f32/chromeos/dbus/shill_manager_client.cc
[modify] https://crrev.com/1dc289654d394f910954978aeab08eb6d2997f32/chromeos/dbus/shill_manager_client.h
[modify] https://crrev.com/1dc289654d394f910954978aeab08eb6d2997f32/chromeos/dbus/shill_manager_client_unittest.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/8b7b238810f3d4a99d633c12dd225a2453fc550c

commit 8b7b238810f3d4a99d633c12dd225a2453fc550c
Author: Toni Barzic <tbarzic@google.com>
Date: Fri Oct 19 19:19:44 2018

Retire network_DestinationVerification

The methods tested by this test are not longer needed, and are being
removed.

BUG=chromium:846971
TEST=None

Change-Id: I1da9af90a2aece141b9e3a1129773532c3dc7eac
Reviewed-on: https://chromium-review.googlesource.com/1289771
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Toni Baržić <tbarzic@chromium.org>
Reviewed-by: Ben Chan <benchan@chromium.org>

[modify] https://crrev.com/8b7b238810f3d4a99d633c12dd225a2453fc550c/chromeos-base/autotest-tests-shill/autotest-tests-shill-9999.ebuild

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/third_party/autotest/+/f4907ccb3f8177acda7c1f8e4438bcd9473de246

commit f4907ccb3f8177acda7c1f8e4438bcd9473de246
Author: Toni Barzic <tbarzic@google.com>
Date: Fri Oct 19 22:07:55 2018

Remove autotests for chromecast verification methods

These methods are no longer used by Chrome (the cert verification is
being done by chrome code).

BUG=chromium:846971
TEST=NONE
CQ-DEPEND=CL:1289771

Change-Id: I37d3bb218b28d6176eebcd649988b160bd026613
Reviewed-on: https://chromium-review.googlesource.com/1289630
Commit-Ready: Toni Baržić <tbarzic@chromium.org>
Tested-by: Toni Baržić <tbarzic@chromium.org>
Reviewed-by: Ben Chan <benchan@chromium.org>

[delete] https://crrev.com/ad33892a27405ebbe755e6c84deadb4f3d178271/client/site_tests/network_DestinationVerification/control
[delete] https://crrev.com/ad33892a27405ebbe755e6c84deadb4f3d178271/client/site_tests/network_DestinationVerification/network_DestinationVerification.py
[delete] https://crrev.com/ad33892a27405ebbe755e6c84deadb4f3d178271/client/cros/scripts/destination

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/ea5895c101dccc43bc3341a87a32d856610e4bd8

commit ea5895c101dccc43bc3341a87a32d856610e4bd8
Author: Toni Barzic <tbarzic@google.com>
Date: Mon Oct 22 01:31:11 2018

shill: Update ebuild not to install crypto-util

The crypto-util shim is not used anymore, and can be removed.

BUG=chromium:846971
TEST=build_packagesa
CQ-DEPEND=CL:1289771

Change-Id: I5626d6851ee9862c3b0e81f2f14623bd5dd6d3d6
Reviewed-on: https://chromium-review.googlesource.com/1286355
Commit-Ready: Kirtika Ruchandani <kirtika@chromium.org>
Tested-by: Toni Baržić <tbarzic@chromium.org>
Reviewed-by: Ben Chan <benchan@chromium.org>

[modify] https://crrev.com/ea5895c101dccc43bc3341a87a32d856610e4bd8/chromeos-base/shill/shill-9999.ebuild

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/platform2/+/48d51b612308d0ffe660571303cc5085e022617a

commit 48d51b612308d0ffe660571303cc5085e022617a
Author: Toni Barzic <tbarzic@google.com>
Date: Mon Oct 22 01:31:11 2018

shill: Removes logic for Chromecast device cert verification

This is not used anymore - the device verification is currently done
fully in Chrome (and has been for some time).

CQ-DEPEND=CL:1286355
TEST=FEATURES=test emerge shill
BUG=chromium:846971

Change-Id: Ic5da34225fb1f1fe0d9bb0738729279790acd275
Reviewed-on: https://chromium-review.googlesource.com/1285534
Commit-Ready: Kirtika Ruchandani <kirtika@chromium.org>
Tested-by: Toni Baržić <tbarzic@chromium.org>
Reviewed-by: Ben Chan <benchan@chromium.org>

[delete] https://crrev.com/ad2825c181fcee5e943115a8ac74a90ba622c329/shill/shims/protos/crypto_util.proto
[delete] https://crrev.com/ad2825c181fcee5e943115a8ac74a90ba622c329/shill/test-scripts/crypto_util_pb2.py
[modify] https://crrev.com/48d51b612308d0ffe660571303cc5085e022617a/shill/BUILD.gn
[delete] https://crrev.com/ad2825c181fcee5e943115a8ac74a90ba622c329/shill/shims/crypto_util.cc
[delete] https://crrev.com/ad2825c181fcee5e943115a8ac74a90ba622c329/shill/mock_crypto_util_proxy.cc
[delete] https://crrev.com/ad2825c181fcee5e943115a8ac74a90ba622c329/shill/mock_crypto_util_proxy.h
[modify] https://crrev.com/48d51b612308d0ffe660571303cc5085e022617a/shill/doc/manager-api.txt
[modify] https://crrev.com/48d51b612308d0ffe660571303cc5085e022617a/shill/dbus_bindings/org.chromium.flimflam.Manager.dbus-xml
[modify] https://crrev.com/48d51b612308d0ffe660571303cc5085e022617a/shill/manager.h
[delete] https://crrev.com/ad2825c181fcee5e943115a8ac74a90ba622c329/shill/crypto_util_proxy.cc
[modify] https://crrev.com/48d51b612308d0ffe660571303cc5085e022617a/shill/manager.cc
[modify] https://crrev.com/48d51b612308d0ffe660571303cc5085e022617a/shill/manager_test.cc
[modify] https://crrev.com/48d51b612308d0ffe660571303cc5085e022617a/shill/dbus/chromeos_manager_dbus_adaptor.cc
[modify] https://crrev.com/48d51b612308d0ffe660571303cc5085e022617a/shill/dbus/chromeos_manager_dbus_adaptor.h
[delete] https://crrev.com/ad2825c181fcee5e943115a8ac74a90ba622c329/shill/crypto_util_proxy_test.cc
[delete] https://crrev.com/ad2825c181fcee5e943115a8ac74a90ba622c329/shill/crypto_util_proxy.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c6bc7f4bef0b76e0f6347f590536ed6601047def

commit c6bc7f4bef0b76e0f6347f590536ed6601047def
Author: Toni Barzic <tbarzic@google.com>
Date: Tue Oct 30 03:25:55 2018

Remove networkingPrivate.verifyAndEncryptCredentials

This was intended to enable auto-filling network credentials during
Chromecast setup, but never actually caught on (i.e. it has not been
actually used).

BUG=846971

Change-Id: I66e5e316ec91eac0c286f82aa4aad1573ed931f8
Reviewed-on: https://chromium-review.googlesource.com/c/1297407
Commit-Queue: Toni Baržić <tbarzic@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#603770}
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/chrome/browser/extensions/BUILD.gn
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/chrome/browser/extensions/api/networking_cast_private/chrome_networking_cast_private_delegate.cc
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/chrome/browser/extensions/api/networking_cast_private/chrome_networking_cast_private_delegate.h
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/chrome/browser/extensions/api/networking_cast_private/networking_cast_private_api.cc
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/chrome/browser/extensions/api/networking_cast_private/networking_cast_private_api.h
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/chrome/browser/extensions/api/networking_cast_private/networking_cast_private_apitest.cc
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/chrome/browser/extensions/api/networking_private/networking_private_apitest.cc
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/chrome/browser/extensions/api/networking_private/networking_private_chromeos_apitest.cc
[delete] https://crrev.com/da315bc8c3b31c17eb6500465951cb84b776292a/chrome/browser/extensions/api/networking_private/networking_private_credentials_getter.h
[delete] https://crrev.com/da315bc8c3b31c17eb6500465951cb84b776292a/chrome/browser/extensions/api/networking_private/networking_private_credentials_getter_browsertest.cc
[delete] https://crrev.com/da315bc8c3b31c17eb6500465951cb84b776292a/chrome/browser/extensions/api/networking_private/networking_private_credentials_getter_chromeos.cc
[delete] https://crrev.com/da315bc8c3b31c17eb6500465951cb84b776292a/chrome/browser/extensions/api/networking_private/networking_private_credentials_getter_mac.cc
[delete] https://crrev.com/da315bc8c3b31c17eb6500465951cb84b776292a/chrome/browser/extensions/api/networking_private/networking_private_credentials_getter_win.cc
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/chrome/browser/extensions/api/networking_private/networking_private_service_client_apitest.cc
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/chrome/common/extensions/api/networking_cast_private.idl
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/chrome/test/BUILD.gn
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/chrome/test/data/extensions/api_test/networking_cast_private/test.js
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/chrome/test/data/extensions/api_test/networking_private/alias/test.js
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/chrome/test/data/extensions/api_test/networking_private/chromeos/test.js
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/chrome/test/data/extensions/api_test/networking_private/service_client/test.js
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/chrome/test/data/extensions/api_test/networking_private/test.js
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/extensions/browser/api/networking_private/networking_cast_private_delegate.h
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/extensions/browser/api/networking_private/networking_private_api.cc
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/extensions/browser/api/networking_private/networking_private_api.h
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/extensions/browser/api/networking_private/networking_private_stubs.cc
[modify] https://crrev.com/c6bc7f4bef0b76e0f6347f590536ed6601047def/extensions/common/api/networking_private.idl