/*
 * Copyright (C) 2016 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.gatekeeper@1.0;

@SensitiveData
interface IGatekeeper {

/**
 * Enrolls desiredPassword, which may be derived from a user selected pin
 * or password, with the private key used only for enrolling authentication
 * factor data.
 *
 * If there was already a password enrolled, current password handle must be
 * passed in currentPasswordHandle, and current password must be passed in
 * currentPassword. Valid currentPassword must verify() against
 * currentPasswordHandle.
 *
 * @param uid The Android user identifier
 *
 * @param currentPasswordHandle The currently enrolled password handle the user
 *    wants to replace. May be empty only if there's no currently enrolled
 *    password. Otherwise must be non-empty.
 *
 * @param currentPassword The user's current password in plain text.
 *    it MUST verify against current_password_handle if the latter is not-empty
 *
 * @param desiredPassword The new password the user wishes to enroll in
 *    plaintext.
 *
 * @return response
 *    On success, data buffer must contain the new password handle referencing
 *    the password provided in desiredPassword.
 *    This buffer can be used on subsequent calls to enroll or
 *    verify. On error, this buffer must be empty.
 *    response.code must always contain operation completion status.
 *    This method may return ERROR_GENERAL_FAILURE or ERROR_RETRY_TIMEOUT on
 *    failure. It must return STATUS_OK on success.
 *    If ERROR_RETRY_TIMEOUT is returned, response.timeout must be non-zero.
 */
enroll(uint32_t uid,
       vec<uint8_t> currentPasswordHandle,
       vec<uint8_t> currentPassword,
       vec<uint8_t> desiredPassword)
    generates (GatekeeperResponse response);

/**
 * Verifies that providedPassword matches enrolledPasswordHandle.
 *
 * Implementations of this module may retain the result of this call
 * to attest to the recency of authentication.
 *
 * On success, returns verification token in response.data, which shall be
 * usable to attest password verification to other trusted services.
 *
 * @param uid The Android user identifier
 *
 * @param challenge An optional challenge to authenticate against, or 0.
 *    Used when a separate authenticator requests password verification,
 *    or for transactional password authentication.
 *
 * @param enrolledPasswordHandle The currently enrolled password handle that
 *    user wishes to verify against. Must be non-empty.
 *
 * @param providedPassword The plaintext password to be verified against the
 *    enrolledPasswordHandle
 *
 * @return response
 *    On success, a non-empty data buffer containing the
 *    authentication token resulting from this verification is returned.
 *    On error, data buffer must be empty.
 *    response.code must always contain operation completion status.
 *    This method may return ERROR_GENERAL_FAILURE or ERROR_RETRY_TIMEOUT on
 *    failure. It must return STATUS_OK on success.
 *    If password re-enrollment is necessary, it must return STATUS_REENROLL.
 *    If ERROR_RETRY_TIMEOUT is returned, response.timeout must be non-zero.
 */
verify(uint32_t uid, uint64_t challenge,
       vec<uint8_t> enrolledPasswordHandle,
       vec<uint8_t> providedPassword)
    generates (GatekeeperResponse response);

/**
 * Deletes the enrolledPasswordHandle associated with the uid. Once deleted
 * the user cannot be verified anymore.
 * This is an optional method.
 *
 * @param uid The Android user identifier
 *
 * @return response
 *    response.code must always contain operation completion status.
 *    This method may return ERROR_GENERAL_FAILURE or ERROR_RETRY_TIMEOUT on
 *    failure. It must return STATUS_OK on success.
 *    If not implemented, it must return ERROR_NOT_IMPLEMENTED.
 *    If ERROR_RETRY_TIMEOUT is returned, response.timeout must be non-zero.
 */
deleteUser(uint32_t uid) generates (GatekeeperResponse response);

/**
 * Deletes all the enrolled_password_handles for all uid's. Once called,
 * no users must be enrolled on the device.
 * This is an optional method.
 *
 * @return response
 *    response.code must always contain operation completion status.
 *    This method may return ERROR_GENERAL_FAILURE or ERROR_RETRY_TIMEOUT on
 *    failure. It must return STATUS_OK on success.
 *    If not implemented, it must return ERROR_NOT_IMPLEMENTED.
 *    If ERROR_RETRY_TIMEOUT is returned, response.timeout must be non-zero.
 */
deleteAllUsers() generates (GatekeeperResponse response);
};
