diff --git a/keymaster/aidl/Android.bp b/keymaster/aidl/Android.bp
index a3800c1..0f2debd 100644
--- a/keymaster/aidl/Android.bp
+++ b/keymaster/aidl/Android.bp
@@ -32,5 +32,11 @@
             version: "3",
             imports: [],
         },
+        {
+            version: "4",
+            imports: [],
+        },
+
     ],
+    frozen: true,
 }
diff --git a/keymaster/aidl/aidl_api/android.hardware.keymaster/4/.hash b/keymaster/aidl/aidl_api/android.hardware.keymaster/4/.hash
new file mode 100644
index 0000000..cfa2965
--- /dev/null
+++ b/keymaster/aidl/aidl_api/android.hardware.keymaster/4/.hash
@@ -0,0 +1 @@
+d60ca1bb57f94508910cac7b8910c85e2a49a11f
diff --git a/keymaster/aidl/aidl_api/android.hardware.keymaster/4/android/hardware/keymaster/HardwareAuthToken.aidl b/keymaster/aidl/aidl_api/android.hardware.keymaster/4/android/hardware/keymaster/HardwareAuthToken.aidl
new file mode 100644
index 0000000..6e84e98
--- /dev/null
+++ b/keymaster/aidl/aidl_api/android.hardware.keymaster/4/android/hardware/keymaster/HardwareAuthToken.aidl
@@ -0,0 +1,44 @@
+/*
+ * Copyright 2020 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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.keymaster;
+/* @hide */
+@VintfStability
+parcelable HardwareAuthToken {
+  long challenge;
+  long userId;
+  long authenticatorId;
+  android.hardware.keymaster.HardwareAuthenticatorType authenticatorType = android.hardware.keymaster.HardwareAuthenticatorType.NONE;
+  android.hardware.keymaster.Timestamp timestamp;
+  byte[] mac;
+}
diff --git a/keymaster/aidl/aidl_api/android.hardware.keymaster/4/android/hardware/keymaster/HardwareAuthenticatorType.aidl b/keymaster/aidl/aidl_api/android.hardware.keymaster/4/android/hardware/keymaster/HardwareAuthenticatorType.aidl
new file mode 100644
index 0000000..9526bed
--- /dev/null
+++ b/keymaster/aidl/aidl_api/android.hardware.keymaster/4/android/hardware/keymaster/HardwareAuthenticatorType.aidl
@@ -0,0 +1,42 @@
+/*
+ * Copyright 2020 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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.keymaster;
+/* @hide */
+@Backing(type="int") @VintfStability
+enum HardwareAuthenticatorType {
+  NONE = 0,
+  PASSWORD = (1 << 0) /* 1 */,
+  FINGERPRINT = (1 << 1) /* 2 */,
+  ANY = 0xFFFFFFFF,
+}
diff --git a/keymaster/aidl/aidl_api/android.hardware.keymaster/4/android/hardware/keymaster/SecurityLevel.aidl b/keymaster/aidl/aidl_api/android.hardware.keymaster/4/android/hardware/keymaster/SecurityLevel.aidl
new file mode 100644
index 0000000..d32ef68
--- /dev/null
+++ b/keymaster/aidl/aidl_api/android.hardware.keymaster/4/android/hardware/keymaster/SecurityLevel.aidl
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2020 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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.keymaster;
+/* @hide */
+@Backing(type="int") @VintfStability
+enum SecurityLevel {
+  SOFTWARE = 0,
+  TRUSTED_ENVIRONMENT = 1,
+  STRONGBOX = 2,
+}
diff --git a/keymaster/aidl/aidl_api/android.hardware.keymaster/4/android/hardware/keymaster/Timestamp.aidl b/keymaster/aidl/aidl_api/android.hardware.keymaster/4/android/hardware/keymaster/Timestamp.aidl
new file mode 100644
index 0000000..5b7b37a
--- /dev/null
+++ b/keymaster/aidl/aidl_api/android.hardware.keymaster/4/android/hardware/keymaster/Timestamp.aidl
@@ -0,0 +1,39 @@
+/*
+ * Copyright 2020 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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.keymaster;
+/* @hide */
+@VintfStability
+parcelable Timestamp {
+  long milliSeconds;
+}
diff --git a/keymaster/aidl/aidl_api/android.hardware.keymaster/4/android/hardware/keymaster/VerificationToken.aidl b/keymaster/aidl/aidl_api/android.hardware.keymaster/4/android/hardware/keymaster/VerificationToken.aidl
new file mode 100644
index 0000000..10fa5e1
--- /dev/null
+++ b/keymaster/aidl/aidl_api/android.hardware.keymaster/4/android/hardware/keymaster/VerificationToken.aidl
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2020 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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.keymaster;
+/* @hide */
+@VintfStability
+parcelable VerificationToken {
+  long challenge;
+  android.hardware.keymaster.Timestamp timestamp;
+  android.hardware.keymaster.SecurityLevel securityLevel = android.hardware.keymaster.SecurityLevel.SOFTWARE;
+  byte[] mac;
+}