diff --git a/mypy.ini b/mypy.ini
--- a/mypy.ini
+++ b/mypy.ini
@@ -11,6 +11,9 @@
 [mypy-libcloud.*]
 ignore_missing_imports = True
 
+[mypy-msgpack.*]
+ignore_missing_imports = True
+
 [mypy-pkg_resources.*]
 ignore_missing_imports = True
 
diff --git a/requirements.txt b/requirements.txt
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,6 +3,7 @@
 # dependency lines, see https://pip.readthedocs.org/en/1.1/requirements.html
 
 click
+msgpack
 typing-extensions >= 3.7.4
 
 # seaweedfs backend
diff --git a/swh/objstorage/api/client.py b/swh/objstorage/api/client.py
--- a/swh/objstorage/api/client.py
+++ b/swh/objstorage/api/client.py
@@ -5,12 +5,13 @@
 
 from typing import Iterator, Optional
 
+import msgpack
+
 from swh.core.api import RPCClient
-from swh.core.utils import iter_chunks
 from swh.model import hashutil
-from swh.objstorage.constants import DEFAULT_LIMIT, ID_DIGEST_LENGTH
+from swh.objstorage.constants import DEFAULT_LIMIT
 from swh.objstorage.exc import Error, ObjNotFoundError, ObjStorageAPIError
-from swh.objstorage.interface import ObjId, ObjStorageInterface
+from swh.objstorage.interface import CompositeObjId, ObjId, ObjStorageInterface
 
 
 class RemoteObjStorage(RPCClient):
@@ -33,17 +34,22 @@
     def restore(self: ObjStorageInterface, content: bytes, obj_id: ObjId) -> None:
         return self.add(content, obj_id, check_presence=False)
 
-    def __iter__(self):
+    def __iter__(self) -> Iterator[CompositeObjId]:
         yield from self.list_content()
 
     def list_content(
         self,
         last_obj_id: Optional[ObjId] = None,
         limit: int = DEFAULT_LIMIT,
-    ) -> Iterator[ObjId]:
+    ) -> Iterator[CompositeObjId]:
         params = {"limit": limit}
         if last_obj_id:
             params["last_obj_id"] = hashutil.hash_to_hex(last_obj_id)
-        yield from iter_chunks(
-            self._get_stream("content", params=params), chunk_size=ID_DIGEST_LENGTH
+        response = self.raw_verb(
+            "get",
+            "content",
+            headers={"accept": "application/x-msgpack"},
+            params=params,
+            stream=True,
         )
+        yield from msgpack.Unpacker(response.raw, raw=True)
diff --git a/swh/objstorage/api/server.py b/swh/objstorage/api/server.py
--- a/swh/objstorage/api/server.py
+++ b/swh/objstorage/api/server.py
@@ -7,8 +7,10 @@
 import functools
 import logging
 import os
+from typing import Iterator
 
 from flask import request
+import msgpack
 
 from swh.core.api import RPCServerApp
 from swh.core.api import encode_data_server as encode_data
@@ -98,9 +100,11 @@
         last_obj_id = bytes.fromhex(last_obj_id)
     limit = int(request.args.get("limit", DEFAULT_LIMIT))
 
-    def generate():
+    def generate() -> Iterator[bytes]:
         with timed_context("list_content"):
-            yield from get_objstorage().list_content(last_obj_id, limit=limit)
+            packer = msgpack.Packer(use_bin_type=True)
+            for obj in get_objstorage().list_content(last_obj_id, limit=limit):
+                yield packer.pack(obj)
 
     return app.response_class(generate())
 
diff --git a/swh/objstorage/backends/azure.py b/swh/objstorage/backends/azure.py
--- a/swh/objstorage/backends/azure.py
+++ b/swh/objstorage/backends/azure.py
@@ -21,7 +21,7 @@
 
 from swh.model import hashutil
 from swh.objstorage.exc import Error, ObjNotFoundError
-from swh.objstorage.interface import ObjId
+from swh.objstorage.interface import CompositeObjId, ObjId
 from swh.objstorage.objstorage import (
     ObjStorage,
     compressors,
@@ -180,7 +180,7 @@
 
         return True
 
-    def __contains__(self, obj_id):
+    def __contains__(self, obj_id: ObjId) -> bool:
         """Does the storage contains the obj_id."""
         hex_obj_id = self._internal_id(obj_id)
         client = self.get_blob_client(hex_obj_id)
@@ -191,7 +191,7 @@
         else:
             return True
 
-    def __iter__(self):
+    def __iter__(self) -> Iterator[CompositeObjId]:
         """Iterate over the objects present in the storage."""
         for client in self.get_all_container_clients():
             for obj in client.list_blobs():
diff --git a/swh/objstorage/backends/generator.py b/swh/objstorage/backends/generator.py
--- a/swh/objstorage/backends/generator.py
+++ b/swh/objstorage/backends/generator.py
@@ -1,9 +1,10 @@
 from itertools import count, islice, repeat
 import logging
 import random
-from typing import Iterator, Optional
+from typing import Generator, Iterator, Optional, cast
 
-from swh.objstorage.interface import ObjId
+from swh.objstorage.constants import ID_HASH_ALGO
+from swh.objstorage.interface import CompositeObjId, ObjId
 from swh.objstorage.objstorage import DEFAULT_LIMIT, ObjStorage
 
 logger = logging.getLogger(__name__)
@@ -189,10 +190,10 @@
     def __contains__(self, obj_id, *args, **kwargs):
         return False
 
-    def __iter__(self):
+    def __iter__(self) -> Iterator[CompositeObjId]:
         i = 1
         while True:
-            j = yield (b"%d" % i)
+            j = yield {ID_HASH_ALGO: b"%d" % i}
             if self.total and i >= self.total:
                 logger.debug("DONE")
                 break
@@ -217,8 +218,10 @@
         self,
         last_obj_id: Optional[ObjId] = None,
         limit: int = DEFAULT_LIMIT,
-    ) -> Iterator[ObjId]:
-        it = iter(self)
+    ) -> Iterator[CompositeObjId]:
+        if isinstance(last_obj_id, dict):
+            last_obj_id = last_obj_id[ID_HASH_ALGO]
+        it = cast(Generator[CompositeObjId, int, None], iter(self))
         if last_obj_id:
             next(it)
             it.send(int(last_obj_id))
diff --git a/swh/objstorage/backends/http.py b/swh/objstorage/backends/http.py
--- a/swh/objstorage/backends/http.py
+++ b/swh/objstorage/backends/http.py
@@ -11,7 +11,7 @@
 
 from swh.model import hashutil
 from swh.objstorage import exc
-from swh.objstorage.interface import ObjId
+from swh.objstorage.interface import CompositeObjId, ObjId
 from swh.objstorage.objstorage import (
     DEFAULT_LIMIT,
     ObjStorage,
@@ -45,11 +45,11 @@
         """Check the configuration for this object storage"""
         return True
 
-    def __contains__(self, obj_id):
+    def __contains__(self, obj_id: ObjId) -> bool:
         resp = self.session.head(self._path(obj_id))
         return resp.status_code == 200
 
-    def __iter__(self):
+    def __iter__(self) -> Iterator[CompositeObjId]:
         raise exc.NonIterableObjStorage("__iter__")
 
     def __len__(self):
@@ -68,7 +68,7 @@
         self,
         last_obj_id: Optional[ObjId] = None,
         limit: int = DEFAULT_LIMIT,
-    ) -> Iterator[ObjId]:
+    ) -> Iterator[CompositeObjId]:
         raise exc.NonIterableObjStorage("__len__")
 
     def get(self, obj_id: ObjId) -> bytes:
diff --git a/swh/objstorage/backends/in_memory.py b/swh/objstorage/backends/in_memory.py
--- a/swh/objstorage/backends/in_memory.py
+++ b/swh/objstorage/backends/in_memory.py
@@ -3,9 +3,11 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
+from typing import Iterator
+
 from swh.objstorage.exc import Error, ObjNotFoundError
-from swh.objstorage.interface import ObjId
-from swh.objstorage.objstorage import ObjStorage, compute_hash
+from swh.objstorage.interface import CompositeObjId, ObjId
+from swh.objstorage.objstorage import ObjStorage, compute_hash, objid_to_default_hex
 
 
 class InMemoryObjStorage(ObjStorage):
@@ -22,10 +24,10 @@
     def check_config(self, *, check_write):
         return True
 
-    def __contains__(self, obj_id):
+    def __contains__(self, obj_id: ObjId) -> bool:
         return obj_id in self.state
 
-    def __iter__(self):
+    def __iter__(self) -> Iterator[CompositeObjId]:
         return iter(sorted(self.state))
 
     def add(self, content: bytes, obj_id: ObjId, check_presence: bool = True) -> None:
@@ -44,7 +46,7 @@
         if obj_id not in self:
             raise ObjNotFoundError(obj_id)
         if compute_hash(self.state[obj_id]) != obj_id:
-            raise Error("Corrupt object %s" % obj_id.hex())
+            raise Error("Corrupt object %s" % objid_to_default_hex(obj_id))
 
     def delete(self, obj_id: ObjId):
         super().delete(obj_id)  # Check delete permission
diff --git a/swh/objstorage/backends/libcloud.py b/swh/objstorage/backends/libcloud.py
--- a/swh/objstorage/backends/libcloud.py
+++ b/swh/objstorage/backends/libcloud.py
@@ -5,8 +5,7 @@
 
 import abc
 from collections import OrderedDict
-from collections.abc import Iterator
-from typing import Optional
+from typing import Iterator, Optional
 from urllib.parse import urlencode
 
 from libcloud.storage import providers
@@ -15,7 +14,7 @@
 
 from swh.model import hashutil
 from swh.objstorage.exc import Error, ObjNotFoundError
-from swh.objstorage.interface import ObjId
+from swh.objstorage.interface import CompositeObjId, ObjId
 from swh.objstorage.objstorage import (
     ObjStorage,
     compressors,
@@ -116,7 +115,7 @@
         # FIXME: hopefully this blew up during instantiation
         return True
 
-    def __contains__(self, obj_id):
+    def __contains__(self, obj_id: ObjId) -> bool:
         try:
             self._get_object(obj_id)
         except ObjNotFoundError:
@@ -124,7 +123,7 @@
         else:
             return True
 
-    def __iter__(self):
+    def __iter__(self) -> Iterator[CompositeObjId]:
         """Iterate over the objects present in the storage
 
         Warning: Iteration over the contents of a cloud-based object storage
diff --git a/swh/objstorage/backends/pathslicing.py b/swh/objstorage/backends/pathslicing.py
--- a/swh/objstorage/backends/pathslicing.py
+++ b/swh/objstorage/backends/pathslicing.py
@@ -12,8 +12,13 @@
 from swh.model import hashutil
 from swh.objstorage.constants import DEFAULT_LIMIT, ID_HASH_ALGO, ID_HEXDIGEST_LENGTH
 from swh.objstorage.exc import Error, ObjNotFoundError
-from swh.objstorage.interface import ObjId
-from swh.objstorage.objstorage import ObjStorage, compressors, decompressors
+from swh.objstorage.interface import CompositeObjId, ObjId
+from swh.objstorage.objstorage import (
+    ObjStorage,
+    compressors,
+    decompressors,
+    objid_to_default_hex,
+)
 
 BUFSIZ = 1048576
 
@@ -182,10 +187,10 @@
         return True
 
     def __contains__(self, obj_id: ObjId) -> bool:
-        hex_obj_id = hashutil.hash_to_hex(obj_id)
+        hex_obj_id = objid_to_default_hex(obj_id)
         return os.path.isfile(self.slicer.get_path(hex_obj_id))
 
-    def __iter__(self) -> Iterator[bytes]:
+    def __iter__(self) -> Iterator[CompositeObjId]:
         """Iterate over the object identifiers currently available in the
         storage.
 
@@ -231,7 +236,7 @@
             # If the object is already present, return immediately.
             return
 
-        hex_obj_id = hashutil.hash_to_hex(obj_id)
+        hex_obj_id = objid_to_default_hex(obj_id)
         compressor = compressors[self.compression]()
         with self._write_obj_file(hex_obj_id) as f:
             f.write(compressor.compress(content))
@@ -242,7 +247,7 @@
             raise ObjNotFoundError(obj_id)
 
         # Open the file and return its content as bytes
-        hex_obj_id = hashutil.hash_to_hex(obj_id)
+        hex_obj_id = objid_to_default_hex(obj_id)
         d = decompressors[self.compression]()
         with open(self.slicer.get_path(hex_obj_id), "rb") as f:
             out = d.decompress(f.read())
@@ -257,7 +262,7 @@
         try:
             data = self.get(obj_id)
         except OSError:
-            hex_obj_id = hashutil.hash_to_hex(obj_id)
+            hex_obj_id = objid_to_default_hex(obj_id)
             raise Error(
                 "Corrupt object %s: not a proper compressed file" % hex_obj_id,
             )
@@ -266,13 +271,13 @@
             data, hash_names=[ID_HASH_ALGO]
         ).digest()
 
-        actual_obj_id = checksums[ID_HASH_ALGO]
-        hex_obj_id = hashutil.hash_to_hex(obj_id)
+        actual_obj_sha1 = checksums[ID_HASH_ALGO]
+        hex_obj_id = objid_to_default_hex(obj_id)
 
-        if hex_obj_id != hashutil.hash_to_hex(actual_obj_id):
+        if hex_obj_id != hashutil.hash_to_hex(actual_obj_sha1):
             raise Error(
                 "Corrupt object %s should have id %s"
-                % (hashutil.hash_to_hex(obj_id), hashutil.hash_to_hex(actual_obj_id))
+                % (objid_to_default_hex(obj_id), hashutil.hash_to_hex(actual_obj_sha1))
             )
 
     def delete(self, obj_id: ObjId):
@@ -280,7 +285,7 @@
         if obj_id not in self:
             raise ObjNotFoundError(obj_id)
 
-        hex_obj_id = hashutil.hash_to_hex(obj_id)
+        hex_obj_id = objid_to_default_hex(obj_id)
         try:
             os.remove(self.slicer.get_path(hex_obj_id))
         except FileNotFoundError:
@@ -291,7 +296,7 @@
 
     @contextmanager
     def chunk_writer(self, obj_id):
-        hex_obj_id = hashutil.hash_to_hex(obj_id)
+        hex_obj_id = objid_to_default_hex(obj_id)
         compressor = compressors[self.compression]()
         with self._write_obj_file(hex_obj_id) as f:
             yield lambda c: f.write(compressor.compress(c))
@@ -299,7 +304,7 @@
 
     def list_content(
         self, last_obj_id: Optional[ObjId] = None, limit: int = DEFAULT_LIMIT
-    ) -> Iterator[ObjId]:
+    ) -> Iterator[CompositeObjId]:
         if last_obj_id:
             it = self.iter_from(last_obj_id)
         else:
@@ -307,7 +312,7 @@
         return islice(it, limit)
 
     def iter_from(self, obj_id, n_leaf=False):
-        hex_obj_id = hashutil.hash_to_hex(obj_id)
+        hex_obj_id = objid_to_default_hex(obj_id)
         slices = self.slicer.get_slices(hex_obj_id)
         rlen = len(self.root.split("/"))
 
diff --git a/swh/objstorage/backends/seaweedfs/objstorage.py b/swh/objstorage/backends/seaweedfs/objstorage.py
--- a/swh/objstorage/backends/seaweedfs/objstorage.py
+++ b/swh/objstorage/backends/seaweedfs/objstorage.py
@@ -11,13 +11,14 @@
 
 from swh.model import hashutil
 from swh.objstorage.exc import Error, ObjNotFoundError
-from swh.objstorage.interface import ObjId
+from swh.objstorage.interface import CompositeObjId, ObjId
 from swh.objstorage.objstorage import (
     DEFAULT_LIMIT,
     ObjStorage,
     compressors,
     compute_hash,
     decompressors,
+    objid_to_default_hex,
 )
 
 from .http import HttpFiler
@@ -41,10 +42,10 @@
         # FIXME: hopefully this blew up during instantiation
         return True
 
-    def __contains__(self, obj_id):
+    def __contains__(self, obj_id: ObjId) -> bool:
         return self.wf.exists(self._path(obj_id))
 
-    def __iter__(self):
+    def __iter__(self) -> Iterator[CompositeObjId]:
         """Iterate over the objects present in the storage
 
         Warning: Iteration over the contents of a cloud-based object storage
@@ -123,9 +124,9 @@
         self,
         last_obj_id: Optional[ObjId] = None,
         limit: int = DEFAULT_LIMIT,
-    ) -> Iterator[ObjId]:
+    ) -> Iterator[CompositeObjId]:
         if last_obj_id:
-            objid = hashutil.hash_to_hex(last_obj_id)
+            objid = objid_to_default_hex(last_obj_id)
             lastfilename = objid
         else:
             lastfilename = None
diff --git a/swh/objstorage/interface.py b/swh/objstorage/interface.py
--- a/swh/objstorage/interface.py
+++ b/swh/objstorage/interface.py
@@ -3,15 +3,24 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
-from typing import Dict, Iterator, List, Optional
+from typing import Dict, Iterator, List, Optional, Union
 
-from typing_extensions import Protocol, runtime_checkable
+from typing_extensions import Protocol, TypedDict, runtime_checkable
 
 from swh.core.api import remote_api_endpoint
 from swh.objstorage.constants import DEFAULT_LIMIT
 
-ObjId = bytes
-"""Type of object ids, which should be a sha1 hash."""
+
+class CompositeObjId(TypedDict, total=False):
+    sha1: bytes
+    sha1_git: bytes
+    sha256: bytes
+    blake2s256: bytes
+
+
+ObjId = Union[bytes, CompositeObjId]
+"""Type of object ids, which should be ``{hash: value for hash in SUPPORTED_HASHES}``;
+but single sha1 hashes are supported for legacy clients"""
 
 
 @runtime_checkable
@@ -172,12 +181,12 @@
         """
         ...
 
-    def __iter__(self) -> Iterator[ObjId]:
+    def __iter__(self) -> Iterator[CompositeObjId]:
         ...
 
     def list_content(
         self, last_obj_id: Optional[ObjId] = None, limit: int = DEFAULT_LIMIT
-    ) -> Iterator[ObjId]:
+    ) -> Iterator[CompositeObjId]:
         """Generates known object ids.
 
         Args:
diff --git a/swh/objstorage/multiplexer/filter/filter.py b/swh/objstorage/multiplexer/filter/filter.py
--- a/swh/objstorage/multiplexer/filter/filter.py
+++ b/swh/objstorage/multiplexer/filter/filter.py
@@ -3,6 +3,9 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
+from typing import Iterator
+
+from swh.objstorage.interface import CompositeObjId
 from swh.objstorage.objstorage import ObjStorage
 
 
@@ -39,7 +42,7 @@
     def __contains__(self, *args, **kwargs):
         return self.storage.__contains__(*args, **kwargs)
 
-    def __iter__(self):
+    def __iter__(self) -> Iterator[CompositeObjId]:
         """Iterates over the content of each storages
 
         Warning: The `__iter__` methods frequently have bad performance. You
diff --git a/swh/objstorage/multiplexer/filter/id_filter.py b/swh/objstorage/multiplexer/filter/id_filter.py
--- a/swh/objstorage/multiplexer/filter/id_filter.py
+++ b/swh/objstorage/multiplexer/filter/id_filter.py
@@ -5,9 +5,11 @@
 
 import abc
 import re
+from typing import Iterator
 
 from swh.model import hashutil
 from swh.objstorage.exc import ObjNotFoundError
+from swh.objstorage.interface import CompositeObjId
 from swh.objstorage.multiplexer.filter.filter import ObjStorageFilter
 
 
@@ -33,7 +35,7 @@
     def __len__(self):
         return sum(1 for i in [id for id in self.storage if self.is_valid(id)])
 
-    def __iter__(self):
+    def __iter__(self) -> Iterator[CompositeObjId]:
         yield from filter(lambda id: self.is_valid(id), iter(self.storage))
 
     def add(self, content, obj_id, check_presence=True, *args, **kwargs):
diff --git a/swh/objstorage/multiplexer/multiplexer_objstorage.py b/swh/objstorage/multiplexer/multiplexer_objstorage.py
--- a/swh/objstorage/multiplexer/multiplexer_objstorage.py
+++ b/swh/objstorage/multiplexer/multiplexer_objstorage.py
@@ -5,10 +5,10 @@
 
 import queue
 import threading
-from typing import Dict
+from typing import Dict, Iterator
 
 from swh.objstorage.exc import ObjNotFoundError
-from swh.objstorage.interface import ObjId
+from swh.objstorage.interface import CompositeObjId, ObjId
 from swh.objstorage.objstorage import ObjStorage
 
 
@@ -199,7 +199,7 @@
             )
         )
 
-    def __contains__(self, obj_id):
+    def __contains__(self, obj_id: ObjId) -> bool:
         """Indicate if the given object is present in the storage.
 
         Args:
@@ -215,7 +215,7 @@
                 return True
         return False
 
-    def __iter__(self):
+    def __iter__(self) -> Iterator[CompositeObjId]:
         def obj_iterator():
             for storage in self.storages:
                 yield from storage
diff --git a/swh/objstorage/objstorage.py b/swh/objstorage/objstorage.py
--- a/swh/objstorage/objstorage.py
+++ b/swh/objstorage/objstorage.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2015-2020  The Software Heritage developers
+# Copyright (C) 2015-2022  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
@@ -14,7 +14,18 @@
 
 from .constants import DEFAULT_LIMIT, ID_HASH_ALGO
 from .exc import ObjNotFoundError
-from .interface import ObjId, ObjStorageInterface
+from .interface import CompositeObjId, ObjId, ObjStorageInterface
+
+
+def objid_to_default_hex(obj_id: ObjId) -> str:
+    """Converts SHA1 hashes and multi-hashes to the hexadecimal representation
+    of the SHA1."""
+    if isinstance(obj_id, bytes):
+        return hashutil.hash_to_hex(obj_id)
+    elif isinstance(obj_id, str):
+        return obj_id
+    else:
+        return hashutil.hash_to_hex(obj_id[ID_HASH_ALGO])
 
 
 def compute_hash(content, algo=ID_HASH_ALGO):
@@ -125,8 +136,9 @@
         self: ObjStorageInterface,
         last_obj_id: Optional[ObjId] = None,
         limit: int = DEFAULT_LIMIT,
-    ) -> Iterator[ObjId]:
+    ) -> Iterator[CompositeObjId]:
         it = iter(self)
-        if last_obj_id is not None:
-            it = dropwhile(last_obj_id.__ge__, it)
+        if last_obj_id:
+            last_obj_id_hex = objid_to_default_hex(last_obj_id)
+            it = dropwhile(lambda x: objid_to_default_hex(x) <= last_obj_id_hex, it)
         return islice(it, limit)
diff --git a/swh/objstorage/tests/objstorage_testing.py b/swh/objstorage/tests/objstorage_testing.py
--- a/swh/objstorage/tests/objstorage_testing.py
+++ b/swh/objstorage/tests/objstorage_testing.py
@@ -23,7 +23,10 @@
         missing_methods = []
 
         for meth_name in dir(interface):
-            if meth_name.startswith("_"):
+            if meth_name.startswith("_") and meth_name not in (
+                "__iter__",
+                "__contains__",
+            ):
                 continue
             interface_meth = getattr(interface, meth_name)
             concrete_meth = getattr(self.storage, meth_name)
diff --git a/swh/objstorage/tests/test_objstorage_random_generator.py b/swh/objstorage/tests/test_objstorage_random_generator.py
--- a/swh/objstorage/tests/test_objstorage_random_generator.py
+++ b/swh/objstorage/tests/test_objstorage_random_generator.py
@@ -21,10 +21,12 @@
     sto = get_objstorage("random", total=100)
     assert isinstance(sto.list_content(), Iterator)
 
-    assert list(sto.list_content()) == [b"%d" % i for i in range(1, 101)]
-    assert list(sto.list_content(limit=10)) == [b"%d" % i for i in range(1, 11)]
+    assert list(sto.list_content()) == [{"sha1": b"%d" % i} for i in range(1, 101)]
+    assert list(sto.list_content(limit=10)) == [
+        {"sha1": b"%d" % i} for i in range(1, 11)
+    ]
     assert list(sto.list_content(last_obj_id=b"10", limit=10)) == [
-        b"%d" % i for i in range(11, 21)
+        {"sha1": b"%d" % i} for i in range(11, 21)
     ]