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/*
* Copyright (C) 2019 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.hardware.keymaster@4.1;
import @4.0::ErrorCode;
import @4.0::HardwareAuthToken;
import @4.0::IKeymasterDevice;
import @4.0::KeyParameter;
import @4.0::KeyPurpose;
import @4.0::OperationHandle;
import @4.0::VerificationToken;
/**
* @4.1::IKeymasterDevice is a minor extension to @4.0::IKeymasterDevice. It adds support for
*
* - Partial hardware enforcment of UNLOCKED_DEVICE_REQUIRED keys;
* - Device-unique attestaion;
* - Early boot only keys;
* - Better cleanup of operations when clients die without completing or aborting them.
*
* @4.1::IKeymasterDevice::attestKey() must produce attestations with keymasterVersion 41. An
* oversight in the original numbering left no room for minor versions, so starting with 4.1 the
* versions will be numbered as major_version * 10 + minor version. The addition of new attestable
* tags changes the attestation format again, slightly, so the attestationVersion must be 4.
*/
@SensitiveData
interface IKeymasterDevice extends @4.0::IKeymasterDevice {
/**
* Called by client to notify the IKeymasterDevice that the device is now locked, and keys with
* the UNLOCKED_DEVICE_REQUIRED tag should no longer be usable. When this function is called,
* the IKeymasterDevice should note the current timestamp, and attempts to use
* UNLOCKED_DEVICE_REQUIRED keys must be rejected with Error::DEVICE_LOCKED until an
* authentication token with a later timestamp is presented. If the `passwordOnly' argument is
* set to true the sufficiently-recent authentication token must indicate that the user
* authenticated with a password, not a biometric.
*
* Note that the IKeymasterDevice UNLOCKED_DEVICE_REQUIRED semantics are slightly different from
* the UNLOCKED_DEVICE_REQUIRED semantics enforced by keystore. Keystore handles device locking
* on a per-user basis. Because auth tokens do not contain an Android user ID, it's not
* possible to replicate the keystore enformcement logic in IKeymasterDevice. So from the
* IKeymasterDevice perspective, any user unlock unlocks all UNLOCKED_DEVICE_REQUIRED keys.
* Keystore will continue enforcing the per-user device locking.
*
* @param passwordOnly specifies whether the device must be unlocked with a password, rather
* than a biometric, before UNLOCKED_DEVICE_REQUIRED keys can be used.
*
* @param verificationToken is used by StrongBox implementations of IKeymasterDevice. It
* provides the StrongBox IKeymasterDevice with a fresh, MACed timestamp which it can use as the
* device-lock time, for future comparison against auth tokens when operations using
* UNLOCKED_DEVICE_REQUIRED keys are attempted. Unless the auth token timestamp is newer than
* the timestamp in the verificationToken, the device is still considered to be locked.
* Crucially, if a StrongBox IKeymasterDevice receives a deviceLocked() call with a verification
* token timestamp that is less than the timestamp in the last deviceLocked() call, it must
* ignore the new timestamp. TEE IKeymasterDevice implementations will receive an empty
* verificationToken (zero values and empty vectors) and should use their own clock as the
* device-lock time.
*/
deviceLocked(bool passwordOnly, VerificationToken verificationToken) generates (ErrorCode error);
/**
* Called by client to notify the IKeymasterDevice that the device has left the early boot
* state, and that keys with the EARLY_BOOT_ONLY tag may no longer be used. All attempts to use
* an EARLY_BOOT_ONLY key after this method is called must fail with Error::INVALID_KEY_BLOB.
*/
earlyBootEnded() generates (ErrorCode error);
};