diff --git a/authfs/aidl/Android.bp b/authfs/aidl/Android.bp
new file mode 100644
index 0000000..8cb9dcf
--- /dev/null
+++ b/authfs/aidl/Android.bp
@@ -0,0 +1,10 @@
+aidl_interface {
+    name: "authfs_aidl_interface",
+    unstable: true,
+    srcs: ["com/android/virt/fs/*.aidl"],
+    backend: {
+        rust: {
+            enabled: true,
+        },
+    },
+}
diff --git a/authfs/aidl/com/android/virt/fs/IVirtFdService.aidl b/authfs/aidl/com/android/virt/fs/IVirtFdService.aidl
new file mode 100644
index 0000000..628ee3c
--- /dev/null
+++ b/authfs/aidl/com/android/virt/fs/IVirtFdService.aidl
@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2021 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 com.android.virt.fs;
+
+/** {@hide} */
+interface IVirtFdService {
+    /** Error when the requesting FD is unknown. */
+    const int ERROR_UNKNOWN_FD = 1;
+
+    /**
+     * Error when I/O fails. This can happen when actual I/O error happens to the backing file,
+     * when the given offset or size are invalid, or any problems that can fail a read/write
+     * request.
+     */
+    const int ERROR_IO = 2;
+
+    /** Maximum content size that the service allows the client to request. */
+    const int MAX_REQUESTING_DATA = 16384;
+
+    /**
+     * Returns the content of the given file ID, from the offset, for the amount of requested size
+     * or until EOF.
+     */
+    byte[] readFile(int id, long offset, int size);
+
+    /**
+     * Returns the content of fs-verity compatible Merkle tree of the given file ID, from the
+     * offset, for the amount of requested size or until EOF.
+     */
+    byte[] readFsverityMerkleTree(int id, long offset, int size);
+
+    /** Returns the fs-verity signature of the given file ID. */
+    byte[] readFsveritySignature(int id);
+}