diff --git a/model_signing/serialization/serialize_by_file_shard.py b/model_signing/serialization/serialize_by_file_shard.py
index 59aa07e8..c16c1fdd 100644
--- a/model_signing/serialization/serialize_by_file_shard.py
+++ b/model_signing/serialization/serialize_by_file_shard.py
@@ -14,10 +14,11 @@
 
 """Model serializers that operated at file shard level of granularity."""
 
+import abc
 import base64
 import concurrent.futures
 import pathlib
-from typing import Callable, Iterable, TypeAlias
+from typing import Callable, Iterable, cast
 from typing_extensions import override
 
 from model_signing.hashing import file
@@ -27,21 +28,16 @@
 from model_signing.serialization import serialize_by_file
 
 
-_ShardSignTask: TypeAlias = tuple[pathlib.PurePath, str, int, int]
-
-
 def _build_header(
     *,
-    entry_name: str,
-    entry_type: str,
+    name: str,
     start: int,
     end: int,
 ) -> bytes:
-    """Builds a header to encode a path with given name and type.
+    """Builds a header to encode a path with given name and shard range.
 
     Args:
         entry_name: The name of the entry to build the header for.
-        entry_type: The type of the entry (file or directory).
         start: Offset for the start of the path shard.
         end: Offset for the end of the path shard.
 
@@ -50,14 +46,11 @@ def _build_header(
         bytes. Each argument is separated by dots and the last byte is also a
         dot (so the file digest can be appended unambiguously).
     """
-    # Note: This will get replaced in subsequent change, right now we're just
-    # moving existing code around.
-    encoded_type = entry_type.encode("utf-8")
     # Prevent confusion if name has a "." inside by encoding to base64.
-    encoded_name = base64.b64encode(entry_name.encode("utf-8"))
+    encoded_name = base64.b64encode(name.encode("utf-8"))
     encoded_range = f"{start}-{end}".encode("utf-8")
     # Note: empty string at the end, to terminate header with a "."
-    return b".".join([encoded_type, encoded_name, encoded_range, b""])
+    return b".".join([encoded_name, encoded_range, b""])
 
 
 def _endpoints(step: int, end: int) -> Iterable[int]:
@@ -83,164 +76,15 @@ def _endpoints(step: int, end: int) -> Iterable[int]:
     yield end
 
 
-class ShardedDFSSerializer(serialization.Serializer):
-    """DFSSerializer that uses a sharded hash engine to exploit parallelism."""
-
-    def __init__(
-        self,
-        file_hasher_factory: Callable[
-            [pathlib.Path, int, int], file.ShardedFileHasher
-        ],
-        merge_hasher: hashing.StreamingHashEngine,
-        max_workers: int | None = None,
-    ):
-        """Initializes an instance to serialize a model with this serializer.
-
-        Args:
-            hasher_factory: A callable to build the hash engine used to hash
-              every shard of the files in the model. Because each shard is
-              processed in parallel, every thread needs to call the factory to
-              start hashing. The arguments are the file, and the endpoints of
-              the shard.
-            merge_hasher: A `hashing.StreamingHashEngine` instance used to merge
-              individual file digests to compute an aggregate digest.
-            max_workers: Maximum number of workers to use in parallel. Default
-              is to defer to the `concurent.futures` library.
-        """
-        self._file_hasher_factory = file_hasher_factory
-        self._merge_hasher = merge_hasher
-        self._max_workers = max_workers
-
-        # Precompute some private values only once by using a mock file hasher.
-        # None of the arguments used to build the hasher are used.
-        hasher = file_hasher_factory(pathlib.Path(), 0, 1)
-        self._shard_size = hasher.shard_size
-
-    @override
-    def serialize(self, model_path: pathlib.Path) -> manifest.DigestManifest:
-        # Note: This function currently uses `pathlib.Path.glob` so the DFS
-        # expansion relies on the `glob` implementation performing a DFS. We
-        # will be truthful again when switching to `pathlib.Path.walk`, after
-        # Python 3.12 is the minimum version we support.
-
-        # TODO: github.com/sigstore/model-transparency/issues/196 - Add checks
-        # to exclude symlinks if desired.
-        serialize_by_file.check_file_or_directory(model_path)
-
-        if model_path.is_file():
-            entries = [model_path]
-        else:
-            # TODO: github.com/sigstore/model-transparency/issues/200 - When
-            # Python3.12 is the minimum supported version, this can be replaced
-            # with `pathlib.Path.walk` for a clearer interface, and some speed
-            # improvement.
-            entries = sorted(model_path.glob("**/*"))
-
-        tasks = self._convert_paths_to_tasks(entries, model_path)
-
-        digest_len = self._merge_hasher.digest_size
-        digests_buffer = bytearray(len(tasks) * digest_len)
-
-        with concurrent.futures.ThreadPoolExecutor(
-            max_workers=self._max_workers
-        ) as tpe:
-            futures_dict = {
-                tpe.submit(self._perform_hash_task, model_path, task): i
-                for i, task in enumerate(tasks)
-            }
-            for future in concurrent.futures.as_completed(futures_dict):
-                i = futures_dict[future]
-                task_digest = future.result()
-
-                task_path, task_type, task_start, task_end = tasks[i]
-                header = _build_header(
-                    entry_name=task_path.name,
-                    entry_type=task_type,
-                    start=task_start,
-                    end=task_end,
-                )
-                self._merge_hasher.reset(header)
-                self._merge_hasher.update(task_digest)
-                digest = self._merge_hasher.compute().digest_value
-
-                start = i * digest_len
-                end = start + digest_len
-                digests_buffer[start:end] = digest
-
-        self._merge_hasher.reset(digests_buffer)
-        return manifest.DigestManifest(self._merge_hasher.compute())
-
-    def _convert_paths_to_tasks(
-        self, paths: Iterable[pathlib.Path], root_path: pathlib.Path
-    ) -> list[_ShardSignTask]:
-        """Returns the tasks that would hash shards of files in parallel.
-
-        Every file in `paths` is replaced by a set of tasks. Each task computes
-        the digest over a shard of the file. Directories result in a single
-        task, just to compute a digest over a header.
-
-        To differentiate between (empty) files and directories with the same
-        name, every task needs to also include a header. The header needs to
-        include relative path to the model root, as we want to obtain the same
-        digest if the model is moved.
-
-        We don't construct an enum for the type of the entry, because these will
-        never escape this class.
-
-        Note that the path component of the tasks is a `pathlib.PurePath`, so
-        operations on it cannot touch the filesystem.
-        """
-        # TODO: github.com/sigstore/model-transparency/issues/196 - Add support
-        # for excluded files.
-
-        tasks = []
-        for path in paths:
-            serialize_by_file.check_file_or_directory(path)
-            relative_path = path.relative_to(root_path)
-
-            if path.is_file():
-                path_size = path.stat().st_size
-                start = 0
-                for end in _endpoints(self._shard_size, path_size):
-                    tasks.append((relative_path, "file", start, end))
-                    start = end
-            else:
-                tasks.append((relative_path, "dir", 0, 0))
-
-        return tasks
-
-    def _perform_hash_task(
-        self, model_path: pathlib.Path, task: _ShardSignTask
-    ) -> bytes:
-        """Produces the hash of the file shard included in `task`."""
-        task_path, task_type, task_start, task_end = task
-
-        # TODO: github.com/sigstore/model-transparency/issues/197 - Directories
-        # don't need to use the file hasher.  Rather than starting a process
-        # just for them, we should filter these ahead of time, and only use
-        # threading for file shards. For now, just return an empty result.
-        if task_type == "dir":
-            return b""
-
-        # TODO: github.com/sigstore/model-transparency/issues/197 - Similarly,
-        # empty files should be hashed outside of a parallel task, to not waste
-        # resources.
-        if task_start == task_end:
-            return b""
-
-        full_path = model_path.joinpath(task_path)
-        hasher = self._file_hasher_factory(full_path, task_start, task_end)
-        return hasher.compute().digest_value
-
-
 class ShardedFilesSerializer(serialization.Serializer):
-    """Model serializers that produces an itemized manifest, at shard level.
+    """Generic file shard serializer.
 
     Traverses the model directory and creates digests for every file found,
     sharding the file in equal shards and computing the digests in parallel.
 
-    Since the manifest lists each item individually, this will also enable
-    support for incremental updates (to be added later).
+    Subclasses can then create a manifest with these digests, either listing
+    them item by item, combining them into file digests, or combining all of
+    them into a single digest.
     """
 
     def __init__(
@@ -270,9 +114,7 @@ def __init__(
         self._shard_size = hasher.shard_size
 
     @override
-    def serialize(
-        self, model_path: pathlib.Path
-    ) -> manifest.ShardLevelManifest:
+    def serialize(self, model_path: pathlib.Path) -> manifest.Manifest:
         # TODO: github.com/sigstore/model-transparency/issues/196 - Add checks
         # to exclude symlinks if desired.
         serialize_by_file.check_file_or_directory(model_path)
@@ -337,12 +179,96 @@ def _compute_hash(
             path=relative_path, digest=digest, start=start, end=end
         )
 
+    @abc.abstractmethod
     def _build_manifest(
         self, items: Iterable[manifest.ShardedFileManifestItem]
-    ) -> manifest.ShardLevelManifest:
+    ) -> manifest.Manifest:
         """Builds an itemized manifest from a given list of items.
 
         Every subclass needs to implement this method to determine the format of
         the manifest.
         """
+        pass
+
+
+class ManifestSerializer(ShardedFilesSerializer):
+    """Model serializers that produces an itemized manifest, at shard level.
+
+    Since the manifest lists each item individually, this will also enable
+    support for incremental updates (to be added later).
+    """
+
+    @override
+    def serialize(
+        self, model_path: pathlib.Path
+    ) -> manifest.ShardLevelManifest:
+        """Serializes the model given by the `model_path` argument.
+
+        The only reason for the override is to change the return type, to be
+        more restrictive. This is to signal that the only manifests that can be
+        returned are `manifest.FileLevelManifest` instances.
+        """
+        return cast(manifest.ShardLevelManifest, super().serialize(model_path))
+
+    @override
+    def _build_manifest(
+        self, items: Iterable[manifest.ShardedFileManifestItem]
+    ) -> manifest.ShardLevelManifest:
         return manifest.ShardLevelManifest(items)
+
+
+class DigestSerializer(ShardedFilesSerializer):
+    """Serializer for a model that performs a traversal of the model directory.
+
+    This serializer produces a single hash for the entire model.
+    """
+
+    def __init__(
+        self,
+        file_hasher_factory: Callable[
+            [pathlib.Path, int, int], file.ShardedFileHasher
+        ],
+        merge_hasher: hashing.StreamingHashEngine,
+        max_workers: int | None = None,
+    ):
+        """Initializes an instance to serialize a model with this serializer.
+
+        Args:
+            hasher_factory: A callable to build the hash engine used to hash
+              every shard of the files in the model. Because each shard is
+              processed in parallel, every thread needs to call the factory to
+              start hashing. The arguments are the file, and the endpoints of
+              the shard.
+            merge_hasher: A `hashing.StreamingHashEngine` instance used to merge
+              individual file shard digests to compute an aggregate digest.
+            max_workers: Maximum number of workers to use in parallel. Default
+              is to defer to the `concurent.futures` library.
+        """
+        super().__init__(file_hasher_factory, max_workers)
+        self._merge_hasher = merge_hasher
+
+    @override
+    def serialize(self, model_path: pathlib.Path) -> manifest.DigestManifest:
+        """Serializes the model given by the `model_path` argument.
+
+        The only reason for the override is to change the return type, to be
+        more restrictive. This is to signal that the only manifests that can be
+        returned are `manifest.FileLevelManifest` instances.
+        """
+        return cast(manifest.DigestManifest, super().serialize(model_path))
+
+    @override
+    def _build_manifest(
+        self, items: Iterable[manifest.ShardedFileManifestItem]
+    ) -> manifest.DigestManifest:
+        self._merge_hasher.reset()
+
+        for item in sorted(items, key=lambda i: (i.path, i.start, i.end)):
+            header = _build_header(
+                name=item.path.name, start=item.start, end=item.end
+            )
+            self._merge_hasher.update(header)
+            self._merge_hasher.update(item.digest.digest_value)
+
+        digest = self._merge_hasher.compute()
+        return manifest.DigestManifest(digest)
diff --git a/model_signing/serialization/serialize_by_file_shard_test.py b/model_signing/serialization/serialize_by_file_shard_test.py
index 59f94047..33510ef0 100644
--- a/model_signing/serialization/serialize_by_file_shard_test.py
+++ b/model_signing/serialization/serialize_by_file_shard_test.py
@@ -29,7 +29,7 @@
 #   pytest model_signing/serialization/ --update_goldens
 
 
-class TestShardedDFSSerializer:
+class TestDigestSerializer:
 
     def _hasher_factory(
         self, path: pathlib.Path, start: int, end: int
@@ -50,13 +50,13 @@ def test_known_models(self, request, model_fixture_name):
         # Set up variables (arrange)
         testdata_path = request.path.parent / "testdata"
         test_path = testdata_path / "serialize_by_file_shard"
-        test_class_path = test_path / "TestShardedDFSSerializer"
+        test_class_path = test_path / "TestDigestSerializer"
         golden_path = test_class_path / model_fixture_name
         should_update = request.config.getoption("update_goldens")
         model = request.getfixturevalue(model_fixture_name)
 
         # Compute model manifest (act)
-        serializer = serialize_by_file_shard.ShardedDFSSerializer(
+        serializer = serialize_by_file_shard.DigestSerializer(
             self._hasher_factory, memory.SHA256()
         )
         manifest = serializer.serialize(model)
@@ -76,13 +76,13 @@ def test_known_models_small_shards(self, request, model_fixture_name):
         # Set up variables (arrange)
         testdata_path = request.path.parent / "testdata"
         test_path = testdata_path / "serialize_by_file_shard"
-        test_class_path = test_path / "TestShardedDFSSerializer"
+        test_class_path = test_path / "TestDigestSerializer"
         golden_path = test_class_path / f"{model_fixture_name}_small_shards"
         should_update = request.config.getoption("update_goldens")
         model = request.getfixturevalue(model_fixture_name)
 
         # Compute model manifest (act)
-        serializer = serialize_by_file_shard.ShardedDFSSerializer(
+        serializer = serialize_by_file_shard.DigestSerializer(
             self._hasher_factory_small_shards, memory.SHA256()
         )
         manifest = serializer.serialize(model)
@@ -98,7 +98,7 @@ def test_known_models_small_shards(self, request, model_fixture_name):
             assert manifest.digest.digest_hex == expected_digest
 
     def test_file_hash_is_not_same_as_hash_of_content(self, sample_model_file):
-        serializer = serialize_by_file_shard.ShardedDFSSerializer(
+        serializer = serialize_by_file_shard.DigestSerializer(
             self._hasher_factory, memory.SHA256()
         )
 
@@ -108,7 +108,7 @@ def test_file_hash_is_not_same_as_hash_of_content(self, sample_model_file):
         assert manifest.digest.digest_hex != digest.digest_hex
 
     def test_file_manifest_unchanged_when_model_moved(self, sample_model_file):
-        serializer = serialize_by_file_shard.ShardedDFSSerializer(
+        serializer = serialize_by_file_shard.DigestSerializer(
             self._hasher_factory, memory.SHA256()
         )
         manifest = serializer.serialize(sample_model_file)
@@ -122,7 +122,7 @@ def test_file_manifest_unchanged_when_model_moved(self, sample_model_file):
     def test_file_model_hash_changes_if_content_changes(
         self, sample_model_file
     ):
-        serializer = serialize_by_file_shard.ShardedDFSSerializer(
+        serializer = serialize_by_file_shard.DigestSerializer(
             self._hasher_factory, memory.SHA256()
         )
         manifest = serializer.serialize(sample_model_file)
@@ -134,7 +134,7 @@ def test_file_model_hash_changes_if_content_changes(
         assert manifest.digest.digest_value != new_manifest.digest.digest_value
 
     def test_directory_model_with_only_known_file(self, sample_model_file):
-        serializer = serialize_by_file_shard.ShardedDFSSerializer(
+        serializer = serialize_by_file_shard.DigestSerializer(
             self._hasher_factory, memory.SHA256()
         )
         manifest_file = serializer.serialize(sample_model_file)
@@ -148,7 +148,7 @@ def test_directory_model_with_only_known_file(self, sample_model_file):
     def test_folder_model_hash_is_same_if_model_is_moved(
         self, sample_model_folder
     ):
-        serializer = serialize_by_file_shard.ShardedDFSSerializer(
+        serializer = serialize_by_file_shard.DigestSerializer(
             self._hasher_factory, memory.SHA256()
         )
         manifest = serializer.serialize(sample_model_folder)
@@ -159,8 +159,8 @@ def test_folder_model_hash_is_same_if_model_is_moved(
 
         assert manifest == new_manifest
 
-    def test_folder_model_empty_folder_gets_included(self, sample_model_folder):
-        serializer = serialize_by_file_shard.ShardedDFSSerializer(
+    def test_folder_model_empty_folder_not_included(self, sample_model_folder):
+        serializer = serialize_by_file_shard.DigestSerializer(
             self._hasher_factory, memory.SHA256()
         )
         manifest = serializer.serialize(sample_model_folder)
@@ -170,10 +170,10 @@ def test_folder_model_empty_folder_gets_included(self, sample_model_folder):
         new_empty_dir.mkdir()
         new_manifest = serializer.serialize(sample_model_folder)
 
-        assert manifest != new_manifest
+        assert manifest == new_manifest
 
-    def test_folder_model_empty_file_gets_included(self, sample_model_folder):
-        serializer = serialize_by_file_shard.ShardedDFSSerializer(
+    def test_folder_model_empty_file_not_included(self, sample_model_folder):
+        serializer = serialize_by_file_shard.DigestSerializer(
             self._hasher_factory, memory.SHA256()
         )
         manifest = serializer.serialize(sample_model_folder)
@@ -183,10 +183,10 @@ def test_folder_model_empty_file_gets_included(self, sample_model_folder):
         new_empty_file.write_text("")
         new_manifest = serializer.serialize(sample_model_folder)
 
-        assert manifest != new_manifest
+        assert manifest == new_manifest
 
     def test_folder_model_rename_file(self, sample_model_folder):
-        serializer = serialize_by_file_shard.ShardedDFSSerializer(
+        serializer = serialize_by_file_shard.DigestSerializer(
             self._hasher_factory, memory.SHA256()
         )
         manifest = serializer.serialize(sample_model_folder)
@@ -200,7 +200,7 @@ def test_folder_model_rename_file(self, sample_model_folder):
         assert manifest != new_manifest
 
     def test_folder_model_rename_dir(self, sample_model_folder):
-        serializer = serialize_by_file_shard.ShardedDFSSerializer(
+        serializer = serialize_by_file_shard.DigestSerializer(
             self._hasher_factory, memory.SHA256()
         )
         manifest = serializer.serialize(sample_model_folder)
@@ -213,7 +213,7 @@ def test_folder_model_rename_dir(self, sample_model_folder):
         assert manifest != new_manifest
 
     def test_folder_model_replace_file_empty_folder(self, sample_model_folder):
-        serializer = serialize_by_file_shard.ShardedDFSSerializer(
+        serializer = serialize_by_file_shard.DigestSerializer(
             self._hasher_factory, memory.SHA256()
         )
         manifest = serializer.serialize(sample_model_folder)
@@ -227,7 +227,7 @@ def test_folder_model_replace_file_empty_folder(self, sample_model_folder):
         assert manifest != new_manifest
 
     def test_folder_model_change_file(self, sample_model_folder):
-        serializer = serialize_by_file_shard.ShardedDFSSerializer(
+        serializer = serialize_by_file_shard.DigestSerializer(
             self._hasher_factory, memory.SHA256()
         )
         manifest = serializer.serialize(sample_model_folder)
@@ -239,22 +239,22 @@ def test_folder_model_change_file(self, sample_model_folder):
 
         assert manifest != new_manifest
 
-    def test_empty_folder_hashes_differently_than_empty_file(
+    def test_empty_folder_hashes_same_as_empty_file(
         self, empty_model_file, empty_model_folder
     ):
-        serializer = serialize_by_file_shard.ShardedDFSSerializer(
+        serializer = serialize_by_file_shard.DigestSerializer(
             self._hasher_factory, memory.SHA256()
         )
 
         folder_manifest = serializer.serialize(empty_model_folder)
         file_manifest = serializer.serialize(empty_model_file)
 
-        assert folder_manifest != file_manifest
+        assert folder_manifest == file_manifest
 
-    def test_model_with_empty_folder_hashes_differently_than_with_empty_file(
+    def test_model_with_empty_folder_hashes_same_as_with_empty_file(
         self, sample_model_folder
     ):
-        serializer = serialize_by_file_shard.ShardedDFSSerializer(
+        serializer = serialize_by_file_shard.DigestSerializer(
             self._hasher_factory, memory.SHA256()
         )
 
@@ -270,15 +270,15 @@ def test_model_with_empty_folder_hashes_differently_than_with_empty_file(
         new_empty_file.write_text("")
         file_manifest = serializer.serialize(sample_model_folder)
 
-        assert folder_manifest != file_manifest
+        assert folder_manifest == file_manifest
 
     def test_max_workers_does_not_change_digest(self, sample_model_folder):
-        serializer1 = serialize_by_file_shard.ShardedDFSSerializer(
+        serializer1 = serialize_by_file_shard.DigestSerializer(
             self._hasher_factory, memory.SHA256()
         )
         manifest1 = serializer1.serialize(sample_model_folder)
 
-        serializer2 = serialize_by_file_shard.ShardedDFSSerializer(
+        serializer2 = serialize_by_file_shard.DigestSerializer(
             self._hasher_factory, memory.SHA256(), max_workers=2
         )
         manifest2 = serializer2.serialize(sample_model_folder)
@@ -286,12 +286,12 @@ def test_max_workers_does_not_change_digest(self, sample_model_folder):
         assert manifest1 == manifest2
 
     def test_shard_size_changes_digests(self, sample_model_folder):
-        serializer1 = serialize_by_file_shard.ShardedDFSSerializer(
+        serializer1 = serialize_by_file_shard.DigestSerializer(
             self._hasher_factory, memory.SHA256()
         )
         manifest1 = serializer1.serialize(sample_model_folder)
 
-        serializer2 = serialize_by_file_shard.ShardedDFSSerializer(
+        serializer2 = serialize_by_file_shard.DigestSerializer(
             self._hasher_factory_small_shards, memory.SHA256()
         )
         manifest2 = serializer2.serialize(sample_model_folder)
@@ -299,7 +299,7 @@ def test_shard_size_changes_digests(self, sample_model_folder):
         assert manifest1.digest.digest_value != manifest2.digest.digest_value
 
 
-@dataclasses.dataclass(frozen=True)
+@dataclasses.dataclass(frozen=True, order=True)
 class _Shard:
     """A shard of a file from a manifest."""
 
@@ -338,7 +338,7 @@ def _parse_shard_and_digest(line: str) -> tuple[_Shard, str]:
     return shard, digest
 
 
-class TestShardedFilesSerializer:
+class TestManifestSerializer:
 
     def _hasher_factory(
         self, path: pathlib.Path, start: int, end: int
@@ -359,13 +359,13 @@ def test_known_models(self, request, model_fixture_name):
         # Set up variables (arrange)
         testdata_path = request.path.parent / "testdata"
         test_path = testdata_path / "serialize_by_file_shard"
-        test_class_path = test_path / "TestShardedFilesSerializer"
+        test_class_path = test_path / "TestManifestSerializer"
         golden_path = test_class_path / model_fixture_name
         should_update = request.config.getoption("update_goldens")
         model = request.getfixturevalue(model_fixture_name)
 
         # Compute model manifest (act)
-        serializer = serialize_by_file_shard.ShardedFilesSerializer(
+        serializer = serialize_by_file_shard.ManifestSerializer(
             self._hasher_factory
         )
         manifest = serializer.serialize(model)
@@ -392,13 +392,13 @@ def test_known_models_small_shards(self, request, model_fixture_name):
         # Set up variables (arrange)
         testdata_path = request.path.parent / "testdata"
         test_path = testdata_path / "serialize_by_file_shard"
-        test_class_path = test_path / "TestShardedFilesSerializer"
+        test_class_path = test_path / "TestManifestSerializer"
         golden_path = test_class_path / f"{model_fixture_name}_small_shards"
         should_update = request.config.getoption("update_goldens")
         model = request.getfixturevalue(model_fixture_name)
 
         # Compute model manifest (act)
-        serializer = serialize_by_file_shard.ShardedFilesSerializer(
+        serializer = serialize_by_file_shard.ManifestSerializer(
             self._hasher_factory_small_shards
         )
         manifest = serializer.serialize(model)
@@ -421,7 +421,7 @@ def test_known_models_small_shards(self, request, model_fixture_name):
             assert items == found_items
 
     def test_file_manifest_unchanged_when_model_moved(self, sample_model_file):
-        serializer = serialize_by_file_shard.ShardedFilesSerializer(
+        serializer = serialize_by_file_shard.ManifestSerializer(
             self._hasher_factory
         )
         manifest = serializer.serialize(sample_model_file)
@@ -433,7 +433,7 @@ def test_file_manifest_unchanged_when_model_moved(self, sample_model_file):
         assert manifest == new_manifest
 
     def test_file_manifest_changes_if_content_changes(self, sample_model_file):
-        serializer = serialize_by_file_shard.ShardedFilesSerializer(
+        serializer = serialize_by_file_shard.ManifestSerializer(
             self._hasher_factory
         )
         manifest = serializer.serialize(sample_model_file)
@@ -450,7 +450,7 @@ def test_file_manifest_changes_if_content_changes(self, sample_model_file):
         assert digests != new_digests
 
     def test_directory_model_with_only_known_file(self, sample_model_file):
-        serializer = serialize_by_file_shard.ShardedFilesSerializer(
+        serializer = serialize_by_file_shard.ManifestSerializer(
             self._hasher_factory
         )
         manifest_file = serializer.serialize(sample_model_file)
@@ -467,7 +467,7 @@ def test_directory_model_with_only_known_file(self, sample_model_file):
     def test_folder_model_hash_is_same_if_model_is_moved(
         self, sample_model_folder
     ):
-        serializer = serialize_by_file_shard.ShardedFilesSerializer(
+        serializer = serialize_by_file_shard.ManifestSerializer(
             self._hasher_factory
         )
         manifest = serializer.serialize(sample_model_folder)
@@ -479,7 +479,7 @@ def test_folder_model_hash_is_same_if_model_is_moved(
         assert manifest == new_manifest
 
     def test_folder_model_empty_folder_not_included(self, sample_model_folder):
-        serializer = serialize_by_file_shard.ShardedFilesSerializer(
+        serializer = serialize_by_file_shard.ManifestSerializer(
             self._hasher_factory
         )
         manifest = serializer.serialize(sample_model_folder)
@@ -492,7 +492,7 @@ def test_folder_model_empty_folder_not_included(self, sample_model_folder):
         assert manifest == new_manifest
 
     def test_folder_model_empty_file_not_included(self, sample_model_folder):
-        serializer = serialize_by_file_shard.ShardedFilesSerializer(
+        serializer = serialize_by_file_shard.ManifestSerializer(
             self._hasher_factory
         )
         manifest = serializer.serialize(sample_model_folder)
@@ -530,7 +530,7 @@ def _check_manifests_match_except_on_renamed_file(
     def test_folder_model_rename_file_only_changes_path_part(
         self, sample_model_folder
     ):
-        serializer = serialize_by_file_shard.ShardedFilesSerializer(
+        serializer = serialize_by_file_shard.ManifestSerializer(
             self._hasher_factory
         )
         manifest = serializer.serialize(sample_model_folder)
@@ -578,7 +578,7 @@ def _check_manifests_match_except_on_renamed_dir(
     def test_folder_model_rename_dir_only_changes_path_part(
         self, sample_model_folder
     ):
-        serializer = serialize_by_file_shard.ShardedFilesSerializer(
+        serializer = serialize_by_file_shard.ManifestSerializer(
             self._hasher_factory
         )
         manifest = serializer.serialize(sample_model_folder)
@@ -594,7 +594,7 @@ def test_folder_model_rename_dir_only_changes_path_part(
         )
 
     def test_folder_model_replace_file_empty_folder(self, sample_model_folder):
-        serializer = serialize_by_file_shard.ShardedFilesSerializer(
+        serializer = serialize_by_file_shard.ManifestSerializer(
             self._hasher_factory
         )
         manifest = serializer.serialize(sample_model_folder)
@@ -633,7 +633,7 @@ def _check_manifests_match_except_on_entry(
                 assert old_manifest._item_to_digest[shard] == digest
 
     def test_folder_model_change_file(self, sample_model_folder):
-        serializer = serialize_by_file_shard.ShardedFilesSerializer(
+        serializer = serialize_by_file_shard.ManifestSerializer(
             self._hasher_factory
         )
         manifest = serializer.serialize(sample_model_folder)
@@ -650,13 +650,13 @@ def test_folder_model_change_file(self, sample_model_folder):
         )
 
     def test_max_workers_does_not_change_digest(self, sample_model_folder):
-        serializer1 = serialize_by_file_shard.ShardedFilesSerializer(
+        serializer1 = serialize_by_file_shard.ManifestSerializer(
             self._hasher_factory
         )
-        serializer2 = serialize_by_file_shard.ShardedFilesSerializer(
+        serializer2 = serialize_by_file_shard.ManifestSerializer(
             self._hasher_factory, max_workers=1
         )
-        serializer3 = serialize_by_file_shard.ShardedFilesSerializer(
+        serializer3 = serialize_by_file_shard.ManifestSerializer(
             self._hasher_factory, max_workers=3
         )
 
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/deep_model_folder b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/deep_model_folder
new file mode 100644
index 00000000..b3a94824
--- /dev/null
+++ b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/deep_model_folder
@@ -0,0 +1 @@
+6deb22c4330a8a9eb5a2d5faa73bf56c64a5c2888961f0f0df51912798fc4954
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/deep_model_folder_small_shards b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/deep_model_folder_small_shards
new file mode 100644
index 00000000..f826b95f
--- /dev/null
+++ b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/deep_model_folder_small_shards
@@ -0,0 +1 @@
+f5203504bea9ec90a7b7453a53c0aaab98a5db5d038dc1fac3613b47f6018959
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/empty_model_folder b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/empty_model_file
similarity index 100%
rename from model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/empty_model_folder
rename to model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/empty_model_file
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/empty_model_folder_small_shards b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/empty_model_file_small_shards
similarity index 100%
rename from model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/empty_model_folder_small_shards
rename to model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/empty_model_file_small_shards
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/empty_model_folder b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/empty_model_folder
new file mode 100644
index 00000000..c3068040
--- /dev/null
+++ b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/empty_model_folder
@@ -0,0 +1 @@
+e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/empty_model_folder_small_shards b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/empty_model_folder_small_shards
new file mode 100644
index 00000000..c3068040
--- /dev/null
+++ b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/empty_model_folder_small_shards
@@ -0,0 +1 @@
+e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/model_folder_with_empty_file b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/model_folder_with_empty_file
new file mode 100644
index 00000000..c3068040
--- /dev/null
+++ b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/model_folder_with_empty_file
@@ -0,0 +1 @@
+e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/model_folder_with_empty_file_small_shards b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/model_folder_with_empty_file_small_shards
new file mode 100644
index 00000000..c3068040
--- /dev/null
+++ b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/model_folder_with_empty_file_small_shards
@@ -0,0 +1 @@
+e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/sample_model_file b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/sample_model_file
new file mode 100644
index 00000000..8ec1d11f
--- /dev/null
+++ b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/sample_model_file
@@ -0,0 +1 @@
+14aebf2e466ad30ef59ea6fce67de44dc133c673784bd543b45f75b8efc3d821
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/sample_model_file_small_shards b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/sample_model_file_small_shards
new file mode 100644
index 00000000..7b4ad705
--- /dev/null
+++ b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/sample_model_file_small_shards
@@ -0,0 +1 @@
+beb3cbbd9d73133e85a102a3cbda2ef1dc2bc61e9323e32e576e4adb0571bf86
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/sample_model_folder b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/sample_model_folder
new file mode 100644
index 00000000..c94ba5d0
--- /dev/null
+++ b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/sample_model_folder
@@ -0,0 +1 @@
+865a7da87d90b261ce99086bfc61986a6230e6914ad885912b4d22464a9fda13
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/sample_model_folder_small_shards b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/sample_model_folder_small_shards
new file mode 100644
index 00000000..6e6fd67f
--- /dev/null
+++ b/model_signing/serialization/testdata/serialize_by_file_shard/TestDigestSerializer/sample_model_folder_small_shards
@@ -0,0 +1 @@
+02be357fc0015ab3d15dbbd363a172f35d2cbd1a854b8e0a6c67fad2e2c3390f
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/deep_model_folder b/model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/deep_model_folder
similarity index 100%
rename from model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/deep_model_folder
rename to model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/deep_model_folder
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/deep_model_folder_small_shards b/model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/deep_model_folder_small_shards
similarity index 100%
rename from model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/deep_model_folder_small_shards
rename to model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/deep_model_folder_small_shards
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/empty_model_file b/model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/empty_model_file
similarity index 100%
rename from model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/empty_model_file
rename to model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/empty_model_file
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/empty_model_file_small_shards b/model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/empty_model_file_small_shards
similarity index 100%
rename from model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/empty_model_file_small_shards
rename to model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/empty_model_file_small_shards
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/empty_model_folder b/model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/empty_model_folder
similarity index 100%
rename from model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/empty_model_folder
rename to model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/empty_model_folder
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/empty_model_folder_small_shards b/model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/empty_model_folder_small_shards
similarity index 100%
rename from model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/empty_model_folder_small_shards
rename to model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/empty_model_folder_small_shards
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/model_folder_with_empty_file b/model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/model_folder_with_empty_file
similarity index 100%
rename from model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/model_folder_with_empty_file
rename to model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/model_folder_with_empty_file
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/model_folder_with_empty_file_small_shards b/model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/model_folder_with_empty_file_small_shards
similarity index 100%
rename from model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/model_folder_with_empty_file_small_shards
rename to model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/model_folder_with_empty_file_small_shards
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/sample_model_file b/model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/sample_model_file
similarity index 100%
rename from model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/sample_model_file
rename to model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/sample_model_file
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/sample_model_file_small_shards b/model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/sample_model_file_small_shards
similarity index 100%
rename from model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/sample_model_file_small_shards
rename to model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/sample_model_file_small_shards
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/sample_model_folder b/model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/sample_model_folder
similarity index 100%
rename from model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/sample_model_folder
rename to model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/sample_model_folder
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/sample_model_folder_small_shards b/model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/sample_model_folder_small_shards
similarity index 100%
rename from model_signing/serialization/testdata/serialize_by_file_shard/TestShardedFilesSerializer/sample_model_folder_small_shards
rename to model_signing/serialization/testdata/serialize_by_file_shard/TestManifestSerializer/sample_model_folder_small_shards
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/deep_model_folder b/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/deep_model_folder
deleted file mode 100644
index 528ab87c..00000000
--- a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/deep_model_folder
+++ /dev/null
@@ -1 +0,0 @@
-52fa3c459aec58bc5f9702c73cb3c6b8fd19e9342aa3e4db851e1bde69ab1727
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/deep_model_folder_small_shards b/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/deep_model_folder_small_shards
deleted file mode 100644
index a4f2f81e..00000000
--- a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/deep_model_folder_small_shards
+++ /dev/null
@@ -1 +0,0 @@
-abd66cd0d8a01f3f552ac5af717f49dc6e6575f0849ec3bfb3c9051962314ce6
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/empty_model_file b/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/empty_model_file
deleted file mode 100644
index 9ac3ea65..00000000
--- a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/empty_model_file
+++ /dev/null
@@ -1 +0,0 @@
-5f2d126b0d3540c17481fdf724e31cf03b4436a2ebabaa1d2e94fe09831be64d
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/empty_model_file_small_shards b/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/empty_model_file_small_shards
deleted file mode 100644
index 9ac3ea65..00000000
--- a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/empty_model_file_small_shards
+++ /dev/null
@@ -1 +0,0 @@
-5f2d126b0d3540c17481fdf724e31cf03b4436a2ebabaa1d2e94fe09831be64d
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/model_folder_with_empty_file b/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/model_folder_with_empty_file
deleted file mode 100644
index b6d24eaf..00000000
--- a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/model_folder_with_empty_file
+++ /dev/null
@@ -1 +0,0 @@
-230d217d5f4f388f5087ac4174dbc9b0ff358e3122a1267b0a56669a44f11ea1
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/model_folder_with_empty_file_small_shards b/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/model_folder_with_empty_file_small_shards
deleted file mode 100644
index b6d24eaf..00000000
--- a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/model_folder_with_empty_file_small_shards
+++ /dev/null
@@ -1 +0,0 @@
-230d217d5f4f388f5087ac4174dbc9b0ff358e3122a1267b0a56669a44f11ea1
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/sample_model_file b/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/sample_model_file
deleted file mode 100644
index a94a0fa0..00000000
--- a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/sample_model_file
+++ /dev/null
@@ -1 +0,0 @@
-2ca48c47d5311a9b2f9305519cd5f927dcef09404fc32ef7886abe8f11450eff
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/sample_model_file_small_shards b/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/sample_model_file_small_shards
deleted file mode 100644
index 5b6697c8..00000000
--- a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/sample_model_file_small_shards
+++ /dev/null
@@ -1 +0,0 @@
-284b613e2e1576d87e5e1c912c82da8d87b6350276f36940516404b2a35f1a74
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/sample_model_folder b/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/sample_model_folder
deleted file mode 100644
index 7fa49a73..00000000
--- a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/sample_model_folder
+++ /dev/null
@@ -1 +0,0 @@
-d22e0441cfa5ac2bc09715ddd88c802a7f97e29c93dc50f5498bab2954958ebb
diff --git a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/sample_model_folder_small_shards b/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/sample_model_folder_small_shards
deleted file mode 100644
index 161cafdf..00000000
--- a/model_signing/serialization/testdata/serialize_by_file_shard/TestShardedDFSSerializer/sample_model_folder_small_shards
+++ /dev/null
@@ -1 +0,0 @@
-82bb608d88cf741730c5bcb75a7630f560643acafdd8fa02ad24be20f51c1250