diff --git a/security/keymint/aidl/vts/functional/Android.bp b/security/keymint/aidl/vts/functional/Android.bp
index 26e91bd..ed3ca74 100644
--- a/security/keymint/aidl/vts/functional/Android.bp
+++ b/security/keymint/aidl/vts/functional/Android.bp
@@ -35,9 +35,12 @@
         "libbinder_ndk",
         "libcrypto",
         "libbase",
+        "libgatekeeper",
         "packagemanager_aidl-cpp",
     ],
     static_libs: [
+        "android.hardware.gatekeeper@1.0",
+        "android.hardware.gatekeeper-V1-ndk",
         "android.hardware.security.rkp-V3-ndk",
         "android.hardware.security.secureclock-V1-ndk",
         "libcppbor_external",
@@ -59,6 +62,7 @@
     ],
     srcs: [
         "AttestKeyTest.cpp",
+        "AuthTest.cpp",
         "DeviceUniqueAttestationTest.cpp",
         "KeyBlobUpgradeTest.cpp",
         "KeyMintTest.cpp",
diff --git a/security/keymint/aidl/vts/functional/AuthTest.cpp b/security/keymint/aidl/vts/functional/AuthTest.cpp
new file mode 100644
index 0000000..a31ac01
--- /dev/null
+++ b/security/keymint/aidl/vts/functional/AuthTest.cpp
@@ -0,0 +1,412 @@
+/*
+ * Copyright (C) 2023 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.
+ */
+
+#define LOG_TAG "keymint_1_test"
+#include <cutils/log.h>
+
+#include <iostream>
+#include <optional>
+
+#include "KeyMintAidlTestBase.h"
+
+#include <aidl/android/hardware/gatekeeper/GatekeeperEnrollResponse.h>
+#include <aidl/android/hardware/gatekeeper/GatekeeperVerifyResponse.h>
+#include <aidl/android/hardware/gatekeeper/IGatekeeper.h>
+#include <aidl/android/hardware/security/secureclock/ISecureClock.h>
+#include <android-base/logging.h>
+#include <android/binder_manager.h>
+
+using aidl::android::hardware::gatekeeper::GatekeeperEnrollResponse;
+using aidl::android::hardware::gatekeeper::GatekeeperVerifyResponse;
+using aidl::android::hardware::gatekeeper::IGatekeeper;
+using aidl::android::hardware::security::keymint::HardwareAuthToken;
+using aidl::android::hardware::security::secureclock::ISecureClock;
+
+#include <android/hardware/gatekeeper/1.0/IGatekeeper.h>
+#include <android/hardware/gatekeeper/1.0/types.h>
+#include <gatekeeper/password_handle.h>  // for password_handle_t
+#include <hardware/hw_auth_token.h>
+
+using ::android::sp;
+using IHidlGatekeeper = ::android::hardware::gatekeeper::V1_0::IGatekeeper;
+using HidlGatekeeperResponse = ::android::hardware::gatekeeper::V1_0::GatekeeperResponse;
+using HidlGatekeeperStatusCode = ::android::hardware::gatekeeper::V1_0::GatekeeperStatusCode;
+
+namespace aidl::android::hardware::security::keymint::test {
+
+class AuthTest : public KeyMintAidlTestBase {
+  public:
+    void SetUp() {
+        KeyMintAidlTestBase::SetUp();
+
+        // Find the default Gatekeeper instance.
+        string gk_name = string(IGatekeeper::descriptor) + "/default";
+        if (AServiceManager_isDeclared(gk_name.c_str())) {
+            // Enroll a user with AIDL Gatekeeper.
+            ::ndk::SpAIBinder binder(AServiceManager_waitForService(gk_name.c_str()));
+            gk_ = IGatekeeper::fromBinder(binder);
+        } else {
+            // Prior to Android U, Gatekeeper was HIDL not AIDL and so may not be present.
+            // Try to enroll user with HIDL Gatekeeper instead.
+            string gk_name = "default";
+            hidl_gk_ = IHidlGatekeeper::getService(gk_name.c_str());
+            if (hidl_gk_ == nullptr) {
+                std::cerr << "No HIDL Gatekeeper instance for '" << gk_name << "' found.\n";
+                return;
+            }
+            std::cerr << "No AIDL Gatekeeper instance for '" << gk_name << "' found, using HIDL.\n";
+        }
+
+        // If the device needs timestamps, find the default ISecureClock instance.
+        if (timestamp_token_required_) {
+            string clock_name = string(ISecureClock::descriptor) + "/default";
+            if (AServiceManager_isDeclared(clock_name.c_str())) {
+                ::ndk::SpAIBinder binder(AServiceManager_waitForService(clock_name.c_str()));
+                clock_ = ISecureClock::fromBinder(binder);
+            } else {
+                std::cerr << "No ISecureClock instance for '" << clock_name << "' found.\n";
+            }
+        }
+
+        // Enroll a password for a user.
+        uid_ = 10001;
+        password_ = "correcthorsebatterystaple";
+        std::optional<GatekeeperEnrollResponse> rsp = doEnroll(password_);
+        ASSERT_TRUE(rsp.has_value());
+        sid_ = rsp->secureUserId;
+        handle_ = rsp->data;
+    }
+
+    void TearDown() {
+        if (gk_ == nullptr) return;
+        gk_->deleteUser(uid_);
+    }
+
+    bool GatekeeperAvailable() { return (gk_ != nullptr) || (hidl_gk_ != nullptr); }
+
+    std::optional<GatekeeperEnrollResponse> doEnroll(const std::vector<uint8_t>& newPwd,
+                                                     const std::vector<uint8_t>& curHandle = {},
+                                                     const std::vector<uint8_t>& curPwd = {}) {
+        if (gk_ != nullptr) {
+            while (true) {
+                GatekeeperEnrollResponse rsp;
+                Status status = gk_->enroll(uid_, curHandle, curPwd, newPwd, &rsp);
+                if (!status.isOk() && status.getExceptionCode() == EX_SERVICE_SPECIFIC &&
+                    status.getServiceSpecificError() == IGatekeeper::ERROR_RETRY_TIMEOUT) {
+                    sleep(1);
+                    continue;
+                }
+                if (status.isOk()) {
+                    return std::move(rsp);
+                } else {
+                    GTEST_LOG_(ERROR) << "doEnroll(AIDL) failed: " << status;
+                    return std::nullopt;
+                }
+            }
+        } else if (hidl_gk_ != nullptr) {
+            while (true) {
+                HidlGatekeeperResponse rsp;
+                auto status = hidl_gk_->enroll(
+                        uid_, curHandle, curPwd, newPwd,
+                        [&rsp](const HidlGatekeeperResponse& cbRsp) { rsp = cbRsp; });
+                if (!status.isOk()) {
+                    GTEST_LOG_(ERROR) << "doEnroll(HIDL) failed";
+                    return std::nullopt;
+                }
+                if (rsp.code == HidlGatekeeperStatusCode::ERROR_RETRY_TIMEOUT) {
+                    sleep(1);
+                    continue;
+                }
+                if (rsp.code != HidlGatekeeperStatusCode::STATUS_OK) {
+                    GTEST_LOG_(ERROR) << "doEnroll(HIDL) failed with " << int(rsp.code);
+                    return std::nullopt;
+                }
+                // "Parse" the returned data to get at the secure user ID.
+                if (rsp.data.size() != sizeof(::gatekeeper::password_handle_t)) {
+                    GTEST_LOG_(ERROR)
+                            << "HAL returned password handle of invalid length " << rsp.data.size();
+                    return std::nullopt;
+                }
+                const ::gatekeeper::password_handle_t* handle =
+                        reinterpret_cast<const ::gatekeeper::password_handle_t*>(rsp.data.data());
+
+                // Translate HIDL response to look like an AIDL response.
+                GatekeeperEnrollResponse aidl_rsp;
+                aidl_rsp.statusCode = IGatekeeper::STATUS_OK;
+                aidl_rsp.data = rsp.data;
+                aidl_rsp.secureUserId = handle->user_id;
+                return aidl_rsp;
+            }
+        } else {
+            return std::nullopt;
+        }
+    }
+
+    std::optional<GatekeeperEnrollResponse> doEnroll(const string& newPwd,
+                                                     const std::vector<uint8_t>& curHandle = {},
+                                                     const string& curPwd = {}) {
+        return doEnroll(std::vector<uint8_t>(newPwd.begin(), newPwd.end()), curHandle,
+                        std::vector<uint8_t>(curPwd.begin(), curPwd.end()));
+    }
+
+    std::optional<HardwareAuthToken> doVerify(uint64_t challenge,
+                                              const std::vector<uint8_t>& handle,
+                                              const std::vector<uint8_t>& pwd) {
+        if (gk_ != nullptr) {
+            while (true) {
+                GatekeeperVerifyResponse rsp;
+                Status status = gk_->verify(uid_, challenge, handle, pwd, &rsp);
+                if (!status.isOk() && status.getExceptionCode() == EX_SERVICE_SPECIFIC &&
+                    status.getServiceSpecificError() == IGatekeeper::ERROR_RETRY_TIMEOUT) {
+                    sleep(1);
+                    continue;
+                }
+                if (status.isOk()) {
+                    return rsp.hardwareAuthToken;
+                } else {
+                    GTEST_LOG_(ERROR) << "doVerify(AIDL) failed: " << status;
+                    return std::nullopt;
+                }
+            }
+        } else if (hidl_gk_ != nullptr) {
+            while (true) {
+                HidlGatekeeperResponse rsp;
+                auto status = hidl_gk_->verify(
+                        uid_, challenge, handle, pwd,
+                        [&rsp](const HidlGatekeeperResponse& cbRsp) { rsp = cbRsp; });
+                if (!status.isOk()) {
+                    GTEST_LOG_(ERROR) << "doVerify(HIDL) failed";
+                    return std::nullopt;
+                }
+                if (rsp.code == HidlGatekeeperStatusCode::ERROR_RETRY_TIMEOUT) {
+                    sleep(1);
+                    continue;
+                }
+                if (rsp.code != HidlGatekeeperStatusCode::STATUS_OK) {
+                    GTEST_LOG_(ERROR) << "doVerify(HIDL) failed with " << int(rsp.code);
+                    return std::nullopt;
+                }
+                // "Parse" the returned data to get auth token contents.
+                if (rsp.data.size() != sizeof(hw_auth_token_t)) {
+                    GTEST_LOG_(ERROR) << "Incorrect size of AuthToken payload.";
+                    return std::nullopt;
+                }
+                const hw_auth_token_t* hwAuthToken =
+                        reinterpret_cast<const hw_auth_token_t*>(rsp.data.data());
+                HardwareAuthToken authToken;
+                authToken.timestamp.milliSeconds = betoh64(hwAuthToken->timestamp);
+                authToken.challenge = hwAuthToken->challenge;
+                authToken.userId = hwAuthToken->user_id;
+                authToken.authenticatorId = hwAuthToken->authenticator_id;
+                authToken.authenticatorType = static_cast<HardwareAuthenticatorType>(
+                        betoh32(hwAuthToken->authenticator_type));
+                authToken.mac.assign(&hwAuthToken->hmac[0], &hwAuthToken->hmac[32]);
+                return authToken;
+            }
+        } else {
+            return std::nullopt;
+        }
+    }
+    std::optional<HardwareAuthToken> doVerify(uint64_t challenge,
+                                              const std::vector<uint8_t>& handle,
+                                              const string& pwd) {
+        return doVerify(challenge, handle, std::vector<uint8_t>(pwd.begin(), pwd.end()));
+    }
+
+    // Variants of the base class methods but with authentication information included.
+    string ProcessMessage(const vector<uint8_t>& key_blob, KeyPurpose operation,
+                          const string& message, const AuthorizationSet& in_params,
+                          AuthorizationSet* out_params, const HardwareAuthToken& hat) {
+        AuthorizationSet begin_out_params;
+        ErrorCode result = Begin(operation, key_blob, in_params, out_params, hat);
+        EXPECT_EQ(ErrorCode::OK, result);
+        if (result != ErrorCode::OK) {
+            return "";
+        }
+
+        std::optional<secureclock::TimeStampToken> time_token = std::nullopt;
+        if (timestamp_token_required_ && clock_ != nullptr) {
+            // Ask a secure clock instance for a timestamp, including the per-op challenge.
+            secureclock::TimeStampToken token;
+            EXPECT_EQ(ErrorCode::OK,
+                      GetReturnErrorCode(clock_->generateTimeStamp(challenge_, &token)));
+            time_token = token;
+        }
+
+        string output;
+        EXPECT_EQ(ErrorCode::OK, Finish(message, {} /* signature */, &output, hat, time_token));
+        return output;
+    }
+
+    string EncryptMessage(const vector<uint8_t>& key_blob, const string& message,
+                          const AuthorizationSet& in_params, AuthorizationSet* out_params,
+                          const HardwareAuthToken& hat) {
+        SCOPED_TRACE("EncryptMessage");
+        return ProcessMessage(key_blob, KeyPurpose::ENCRYPT, message, in_params, out_params, hat);
+    }
+
+    string DecryptMessage(const vector<uint8_t>& key_blob, const string& ciphertext,
+                          const AuthorizationSet& params, const HardwareAuthToken& hat) {
+        SCOPED_TRACE("DecryptMessage");
+        AuthorizationSet out_params;
+        string plaintext =
+                ProcessMessage(key_blob, KeyPurpose::DECRYPT, ciphertext, params, &out_params, hat);
+        EXPECT_TRUE(out_params.empty());
+        return plaintext;
+    }
+
+  protected:
+    std::shared_ptr<IGatekeeper> gk_;
+    sp<IHidlGatekeeper> hidl_gk_;
+    std::shared_ptr<ISecureClock> clock_;
+    string password_;
+    uint32_t uid_;
+    long sid_;
+    std::vector<uint8_t> handle_;
+};
+
+// Test use of a key that requires user-authentication within recent history.
+TEST_P(AuthTest, TimeoutAuthentication) {
+    if (!GatekeeperAvailable()) {
+        GTEST_SKIP() << "No Gatekeeper available";
+    }
+    if (timestamp_token_required_ && clock_ == nullptr) {
+        GTEST_SKIP() << "Device requires timestamps and no ISecureClock available";
+    }
+
+    // Create an AES key that requires authentication within the last 3 seconds.
+    const uint32_t timeout_secs = 3;
+    auto builder = AuthorizationSetBuilder()
+                           .AesEncryptionKey(256)
+                           .BlockMode(BlockMode::ECB)
+                           .Padding(PaddingMode::PKCS7)
+                           .Authorization(TAG_USER_SECURE_ID, sid_)
+                           .Authorization(TAG_USER_AUTH_TYPE, HardwareAuthenticatorType::PASSWORD)
+                           .Authorization(TAG_AUTH_TIMEOUT, timeout_secs);
+    vector<uint8_t> keyblob;
+    vector<KeyCharacteristics> key_characteristics;
+    vector<Certificate> cert_chain;
+    ASSERT_EQ(ErrorCode::OK,
+              GenerateKey(builder, std::nullopt, &keyblob, &key_characteristics, &cert_chain));
+
+    // Attempt to use the AES key without authentication.
+    const string message = "Hello World!";
+    AuthorizationSet out_params;
+    auto params = AuthorizationSetBuilder().BlockMode(BlockMode::ECB).Padding(PaddingMode::PKCS7);
+    EXPECT_EQ(ErrorCode::KEY_USER_NOT_AUTHENTICATED,
+              Begin(KeyPurpose::ENCRYPT, keyblob, params, &out_params));
+
+    // Verify to get a HAT, arbitrary challenge.
+    const uint64_t challenge = 42;
+    const std::optional<HardwareAuthToken> hat = doVerify(challenge, handle_, password_);
+    ASSERT_TRUE(hat.has_value());
+    EXPECT_EQ(hat->userId, sid_);
+
+    // Adding the auth token makes it possible to use the AES key.
+    const string ciphertext = EncryptMessage(keyblob, message, params, &out_params, hat.value());
+    const string plaintext = DecryptMessage(keyblob, ciphertext, params, hat.value());
+    EXPECT_EQ(message, plaintext);
+
+    // Altering a single bit in the MAC means no auth.
+    HardwareAuthToken dodgy_hat = hat.value();
+    ASSERT_GT(dodgy_hat.mac.size(), 0);
+    dodgy_hat.mac[0] ^= 0x01;
+    EXPECT_EQ(ErrorCode::KEY_USER_NOT_AUTHENTICATED,
+              Begin(KeyPurpose::ENCRYPT, keyblob, params, &out_params, dodgy_hat));
+
+    // Wait for long enough that the hardware auth token expires.
+    sleep(timeout_secs + 1);
+    if (!timestamp_token_required_) {
+        // KeyMint implementation has its own clock, and can immediately detect timeout.
+        EXPECT_EQ(ErrorCode::KEY_USER_NOT_AUTHENTICATED,
+                  Begin(KeyPurpose::ENCRYPT, keyblob, params, &out_params, hat));
+    } else {
+        // KeyMint implementation has no clock, so only detects timeout via timestamp token provided
+        // on update()/finish().
+        ASSERT_EQ(ErrorCode::OK, Begin(KeyPurpose::ENCRYPT, keyblob, params, &out_params, hat));
+        secureclock::TimeStampToken time_token;
+        EXPECT_EQ(ErrorCode::OK,
+                  GetReturnErrorCode(clock_->generateTimeStamp(challenge_, &time_token)));
+
+        string output;
+        EXPECT_EQ(ErrorCode::KEY_USER_NOT_AUTHENTICATED,
+                  Finish(message, {} /* signature */, &output, hat, time_token));
+    }
+}
+
+// Test use of a key that requires an auth token for each action on the operation, with
+// a per-operation challenge value included.
+TEST_P(AuthTest, AuthPerOperation) {
+    if (!GatekeeperAvailable()) {
+        GTEST_SKIP() << "No Gatekeeper available";
+    }
+
+    // Create an AES key that requires authentication per-action.
+    auto builder = AuthorizationSetBuilder()
+                           .AesEncryptionKey(256)
+                           .BlockMode(BlockMode::ECB)
+                           .Padding(PaddingMode::PKCS7)
+                           .Authorization(TAG_USER_SECURE_ID, sid_)
+                           .Authorization(TAG_USER_AUTH_TYPE, HardwareAuthenticatorType::PASSWORD);
+    vector<uint8_t> keyblob;
+    vector<KeyCharacteristics> key_characteristics;
+    vector<Certificate> cert_chain;
+    ASSERT_EQ(ErrorCode::OK,
+              GenerateKey(builder, std::nullopt, &keyblob, &key_characteristics, &cert_chain));
+
+    // Attempt to use the AES key without authentication fails after begin.
+    const string message = "Hello World!";
+    AuthorizationSet out_params;
+    auto params = AuthorizationSetBuilder().BlockMode(BlockMode::ECB).Padding(PaddingMode::PKCS7);
+    EXPECT_EQ(ErrorCode::OK, Begin(KeyPurpose::ENCRYPT, keyblob, params, &out_params));
+    string output;
+    EXPECT_EQ(ErrorCode::KEY_USER_NOT_AUTHENTICATED, Finish(message, {} /* signature */, &output));
+
+    // Verify to get a HAT, but with an arbitrary challenge.
+    const uint64_t unrelated_challenge = 42;
+    const std::optional<HardwareAuthToken> unrelated_hat =
+            doVerify(unrelated_challenge, handle_, password_);
+    ASSERT_TRUE(unrelated_hat.has_value());
+    EXPECT_EQ(unrelated_hat->userId, sid_);
+
+    // Attempt to use the AES key with an unrelated authentication fails after begin.
+    EXPECT_EQ(ErrorCode::OK,
+              Begin(KeyPurpose::ENCRYPT, keyblob, params, &out_params, unrelated_hat.value()));
+    EXPECT_EQ(ErrorCode::KEY_USER_NOT_AUTHENTICATED,
+              Finish(message, {} /* signature */, &output, unrelated_hat.value()));
+
+    // Now get a HAT with the challenge from an in-progress operation.
+    EXPECT_EQ(ErrorCode::OK, Begin(KeyPurpose::ENCRYPT, keyblob, params, &out_params));
+    const std::optional<HardwareAuthToken> hat = doVerify(challenge_, handle_, password_);
+    ASSERT_TRUE(hat.has_value());
+    EXPECT_EQ(hat->userId, sid_);
+    string ciphertext;
+    EXPECT_EQ(ErrorCode::OK, Finish(message, {} /* signature */, &ciphertext, hat.value()));
+
+    // Altering a single bit in the MAC means no auth.
+    EXPECT_EQ(ErrorCode::OK, Begin(KeyPurpose::ENCRYPT, keyblob, params, &out_params));
+    std::optional<HardwareAuthToken> dodgy_hat = doVerify(challenge_, handle_, password_);
+    ASSERT_TRUE(dodgy_hat.has_value());
+    EXPECT_EQ(dodgy_hat->userId, sid_);
+    ASSERT_GT(dodgy_hat->mac.size(), 0);
+    dodgy_hat->mac[0] ^= 0x01;
+    EXPECT_EQ(ErrorCode::KEY_USER_NOT_AUTHENTICATED,
+              Finish(message, {} /* signature */, &ciphertext, hat.value()));
+}
+
+INSTANTIATE_KEYMINT_AIDL_TEST(AuthTest);
+
+}  // namespace aidl::android::hardware::security::keymint::test
diff --git a/security/keymint/aidl/vts/functional/KeyMintAidlTestBase.cpp b/security/keymint/aidl/vts/functional/KeyMintAidlTestBase.cpp
index 588a1d4..3ffb6ec 100644
--- a/security/keymint/aidl/vts/functional/KeyMintAidlTestBase.cpp
+++ b/security/keymint/aidl/vts/functional/KeyMintAidlTestBase.cpp
@@ -544,12 +544,13 @@
 
 ErrorCode KeyMintAidlTestBase::Begin(KeyPurpose purpose, const vector<uint8_t>& key_blob,
                                      const AuthorizationSet& in_params,
-                                     AuthorizationSet* out_params) {
+                                     AuthorizationSet* out_params,
+                                     std::optional<HardwareAuthToken> hat) {
     SCOPED_TRACE("Begin");
     Status result;
     BeginResult out;
 
-    result = keymint_->begin(purpose, key_blob, in_params.vector_data(), std::nullopt, &out);
+    result = keymint_->begin(purpose, key_blob, in_params.vector_data(), hat, &out);
 
     if (result.isOk()) {
         *out_params = out.params;
@@ -603,8 +604,9 @@
     return GetReturnErrorCode(result);
 }
 
-ErrorCode KeyMintAidlTestBase::Finish(const string& input, const string& signature,
-                                      string* output) {
+ErrorCode KeyMintAidlTestBase::Finish(const string& input, const string& signature, string* output,
+                                      std::optional<HardwareAuthToken> hat,
+                                      std::optional<secureclock::TimeStampToken> time_token) {
     SCOPED_TRACE("Finish");
     Status result;
 
@@ -613,8 +615,8 @@
 
     vector<uint8_t> oPut;
     result = op_->finish(vector<uint8_t>(input.begin(), input.end()),
-                         vector<uint8_t>(signature.begin(), signature.end()), {} /* authToken */,
-                         {} /* timestampToken */, {} /* confirmationToken */, &oPut);
+                         vector<uint8_t>(signature.begin(), signature.end()), hat, time_token,
+                         {} /* confirmationToken */, &oPut);
 
     if (result.isOk()) output->append(oPut.begin(), oPut.end());
 
diff --git a/security/keymint/aidl/vts/functional/KeyMintAidlTestBase.h b/security/keymint/aidl/vts/functional/KeyMintAidlTestBase.h
index fae9459..2a0a19d 100644
--- a/security/keymint/aidl/vts/functional/KeyMintAidlTestBase.h
+++ b/security/keymint/aidl/vts/functional/KeyMintAidlTestBase.h
@@ -160,7 +160,8 @@
                     const AuthorizationSet& in_params, AuthorizationSet* out_params,
                     std::shared_ptr<IKeyMintOperation>& op);
     ErrorCode Begin(KeyPurpose purpose, const vector<uint8_t>& key_blob,
-                    const AuthorizationSet& in_params, AuthorizationSet* out_params);
+                    const AuthorizationSet& in_params, AuthorizationSet* out_params,
+                    std::optional<HardwareAuthToken> hat = std::nullopt);
     ErrorCode Begin(KeyPurpose purpose, const AuthorizationSet& in_params,
                     AuthorizationSet* out_params);
     ErrorCode Begin(KeyPurpose purpose, const AuthorizationSet& in_params);
@@ -168,7 +169,9 @@
     ErrorCode UpdateAad(const string& input);
     ErrorCode Update(const string& input, string* output);
 
-    ErrorCode Finish(const string& message, const string& signature, string* output);
+    ErrorCode Finish(const string& message, const string& signature, string* output,
+                     std::optional<HardwareAuthToken> hat = std::nullopt,
+                     std::optional<secureclock::TimeStampToken> time_token = std::nullopt);
     ErrorCode Finish(const string& message, string* output) {
         return Finish(message, {} /* signature */, output);
     }