diff --git a/src/iokit/__init__.py b/src/iokit/__init__.py
index 14ded44..f3a658b 100644
--- a/src/iokit/__init__.py
+++ b/src/iokit/__init__.py
@@ -1,33 +1,36 @@
+__version__ = "0.2.0"
 __all__ = [
     "Dat",
-    "Encryption",
+    "decrypt",
+    "download_file",
+    "Enc",
+    "encrypt",
     "Env",
+    "filter_states",
+    "find_state",
+    "Flac",
     "Gzip",
     "Json",
     "Jsonl",
-    "Tar",
-    "Txt",
-    "Yaml",
-    "Zip",
+    "load_file",
     "Mp3",
     "Npy",
-    "Wav",
-    "Waveform",
-    "Flac",
     "Ogg",
-    "State",
-    "filter_states",
-    "find_state",
-    "download_file",
-    "load_file",
     "save_file",
     "save_temp",
+    "SecretState",
+    "State",
+    "Tar",
+    "Txt",
+    "Waveform",
+    "Wav",
+    "Yaml",
+    "Zip",
 ]
-__version__ = "0.2.0"
 
 from .extensions import (
     Dat,
-    Encryption,
+    Enc,
     Env,
     Flac,
     Gzip,
@@ -36,12 +39,15 @@
     Mp3,
     Npy,
     Ogg,
+    SecretState,
     Tar,
     Txt,
     Wav,
     Waveform,
     Yaml,
     Zip,
+    decrypt,
+    encrypt,
 )
 from .state import State, filter_states, find_state
 from .storage import download_file, load_file, save_file, save_temp
diff --git a/src/iokit/extensions/__init__.py b/src/iokit/extensions/__init__.py
index 0ea2ed8..9f7950a 100644
--- a/src/iokit/extensions/__init__.py
+++ b/src/iokit/extensions/__init__.py
@@ -1,25 +1,28 @@
 __all__ = [
-    "Flac",
-    "Mp3",
-    "Ogg",
-    "Wav",
-    "Waveform",
     "Dat",
-    "Encryption",
+    "Enc",
     "Env",
+    "Flac",
     "Gzip",
     "Json",
     "Jsonl",
+    "Mp3",
     "Npy",
+    "Ogg",
+    "SecretState",
     "Tar",
     "Txt",
+    "Wav",
+    "Waveform",
     "Yaml",
     "Zip",
+    "decrypt",
+    "encrypt",
 ]
 
 from .audio import Flac, Mp3, Ogg, Wav, Waveform
 from .dat import Dat
-from .enc import Encryption
+from .enc import Enc, SecretState, decrypt, encrypt
 from .env import Env
 from .gz import Gzip
 from .json import Json
diff --git a/src/iokit/extensions/audio.py b/src/iokit/extensions/audio.py
index 7bffb78..7f39391 100644
--- a/src/iokit/extensions/audio.py
+++ b/src/iokit/extensions/audio.py
@@ -1,3 +1,5 @@
+__all__ = ["Waveform", "Flac", "Wav", "Mp3", "Ogg"]
+
 from dataclasses import dataclass
 from io import BytesIO
 from typing import Any
@@ -11,16 +13,17 @@
 
 class AudioState(State, suffix=""):
     def __init__(self, waveform: "Waveform", **kwargs: Any):
-        soundfile.write(
-            file=(target := BytesIO()),
-            data=waveform.wave,
-            samplerate=waveform.freq,
-            format=self._suffix,
-        )
-        super().__init__(data=target.getvalue(), **kwargs)
+        with BytesIO() as buffer:
+            soundfile.write(
+                file=buffer,
+                data=waveform.wave,
+                samplerate=waveform.freq,
+                format=self._suffix,
+            )
+            super().__init__(data=buffer.getvalue(), **kwargs)
 
     def load(self) -> "Waveform":
-        wave, freq = soundfile.read(self.data, always_2d=True)
+        wave, freq = soundfile.read(self.buffer, always_2d=True)
         return Waveform(wave=wave, freq=freq)
 
 
diff --git a/src/iokit/extensions/dat.py b/src/iokit/extensions/dat.py
index 0cc3b02..e474256 100644
--- a/src/iokit/extensions/dat.py
+++ b/src/iokit/extensions/dat.py
@@ -1,15 +1,13 @@
-__all__ = [
-    "Dat",
-]
+__all__ = ["Dat"]
 
 from typing import Any
 
-from iokit.state import Payload, State
+from iokit.state import State
 
 
 class Dat(State, suffix="dat"):
-    def __init__(self, data: Payload, **kwargs: Any):
+    def __init__(self, data: bytes, **kwargs: Any):
         super().__init__(data=data, **kwargs)
 
     def load(self) -> bytes:
-        return self._data.getvalue()
+        return self.data
diff --git a/src/iokit/extensions/enc.py b/src/iokit/extensions/enc.py
index 5648f49..aa32633 100644
--- a/src/iokit/extensions/enc.py
+++ b/src/iokit/extensions/enc.py
@@ -1,3 +1,5 @@
+__all__ = ["SecretState", "Enc", "encrypt", "decrypt"]
+
 import struct
 from collections.abc import Iterator
 from hashlib import sha256
@@ -91,12 +93,12 @@ def __repr__(self) -> str:
 
     @classmethod
     def pack(cls, state: State, password: bytes | str, salt: bytes | str = b"42") -> Self:
-        payload = _pack_arrays(str(state.name).encode("utf-8"), state.data.getvalue())
+        payload = _pack_arrays(str(state.name).encode("utf-8"), state.data)
         data = encrypt(data=payload, password=_to_bytes(password), salt=_to_bytes(salt))
         return cls(data=data)
 
 
-class Encryption(State, suffix="enc"):
+class Enc(State, suffix="enc"):
     def __init__(
         self,
         state: State,
@@ -112,4 +114,4 @@ def __init__(
         super().__init__(data=data, name=name, **kwargs)
 
     def load(self) -> SecretState:
-        return SecretState(data=self.data.getvalue())
+        return SecretState(data=self.data)
diff --git a/src/iokit/extensions/env.py b/src/iokit/extensions/env.py
index d0595f3..7a75feb 100644
--- a/src/iokit/extensions/env.py
+++ b/src/iokit/extensions/env.py
@@ -1,3 +1,5 @@
+__all__ = ["Env"]
+
 from io import StringIO
 from pathlib import Path
 from tempfile import TemporaryDirectory
@@ -20,5 +22,5 @@ def __init__(self, data: dict[str, str], **kwargs: Any):
         super().__init__(data=data_bytes, **kwargs)
 
     def load(self) -> dict[str, str | None]:
-        stream = StringIO(self.data.getvalue().decode())
-        return dict(dotenv.dotenv_values(stream=stream))
+        with StringIO(self.data.decode()) as stream:
+            return dict(dotenv.dotenv_values(stream=stream))
diff --git a/src/iokit/extensions/gz.py b/src/iokit/extensions/gz.py
index 72f5b0f..9891fb6 100644
--- a/src/iokit/extensions/gz.py
+++ b/src/iokit/extensions/gz.py
@@ -1,3 +1,5 @@
+__all__ = ["Gzip"]
+
 import gzip
 from io import BytesIO
 from typing import Any
@@ -7,14 +9,13 @@
 
 class Gzip(State, suffix="gz"):
     def __init__(self, state: State, *, compression: int = 1, **kwargs: Any):
-        data = BytesIO()
-        gzip_file = gzip.GzipFile(fileobj=data, mode="wb", compresslevel=compression, mtime=0)
-        with gzip_file as gzip_buffer:
-            gzip_buffer.write(state.data.getvalue())
-        super().__init__(data=data, name=state.name, **kwargs)
+        with BytesIO() as buffer:
+            gzip_file = gzip.GzipFile(fileobj=buffer, mode="wb", compresslevel=compression, mtime=0)
+            with gzip_file as gzip_buffer:
+                gzip_buffer.write(state.data)
+            super().__init__(data=buffer.getvalue(), name=state.name, **kwargs)
 
     def load(self) -> State:
-        gzip_file = gzip.GzipFile(fileobj=self.data, mode="rb")
-        with gzip_file as file:
-            data = file.read()
-        return State(data=data, name=str(self.name).removesuffix(".gz")).cast()
+        # gzip_file =
+        with gzip.GzipFile(fileobj=self.buffer, mode="rb") as file:
+            return State(data=file.read(), name=str(self.name).removesuffix(".gz")).cast()
diff --git a/src/iokit/extensions/json.py b/src/iokit/extensions/json.py
index 3efe604..5ebfa89 100644
--- a/src/iokit/extensions/json.py
+++ b/src/iokit/extensions/json.py
@@ -1,6 +1,4 @@
-__all__ = [
-    "Json",
-]
+__all__ = ["Json"]
 
 import json
 from collections.abc import Callable
@@ -42,4 +40,4 @@ def __init__(
         super().__init__(data=data_, **kwargs)
 
     def load(self) -> Any:
-        return json.load(self.data)
+        return json.load(self.buffer)
diff --git a/src/iokit/extensions/jsonl.py b/src/iokit/extensions/jsonl.py
index c176283..6fdaedc 100644
--- a/src/iokit/extensions/jsonl.py
+++ b/src/iokit/extensions/jsonl.py
@@ -1,6 +1,4 @@
-__all__ = [
-    "Jsonl",
-]
+__all__ = ["Jsonl"]
 
 from collections.abc import Iterable
 from io import BytesIO
@@ -23,13 +21,13 @@ def __init__(
         allow_nan: bool = False,
         **kwargs: Any,
     ):
-        buffer = BytesIO()
-        dumps = json_dumps(compact=compact, ensure_ascii=ensure_ascii, allow_nan=allow_nan)
-        with Writer(buffer, compact=compact, sort_keys=False, dumps=dumps) as writer:
-            for item in sequence:
-                writer.write(item)
-        super().__init__(data=buffer, **kwargs)
+        with BytesIO() as buffer:
+            dumps = json_dumps(compact=compact, ensure_ascii=ensure_ascii, allow_nan=allow_nan)
+            with Writer(buffer, compact=compact, sort_keys=False, dumps=dumps) as writer:
+                for item in sequence:
+                    writer.write(item)
+            super().__init__(data=buffer.getvalue(), **kwargs)
 
     def load(self) -> list[Any]:
-        with Reader(self.data) as reader:
+        with Reader(self.buffer) as reader:
             return list(reader)
diff --git a/src/iokit/extensions/npy.py b/src/iokit/extensions/npy.py
index 4377265..a31a02c 100644
--- a/src/iokit/extensions/npy.py
+++ b/src/iokit/extensions/npy.py
@@ -1,3 +1,5 @@
+__all__ = ["Npy"]
+
 from io import BytesIO
 from typing import Any
 
@@ -14,4 +16,4 @@ def __init__(self, array: NDArray[Any], **kwargs: Any) -> None:
             super().__init__(data=buffer.getvalue(), **kwargs)
 
     def load(self) -> NDArray[Any]:
-        return np.load(self.data, allow_pickle=False, fix_imports=False)
+        return np.load(self.buffer, allow_pickle=False, fix_imports=False)
diff --git a/src/iokit/extensions/tar.py b/src/iokit/extensions/tar.py
index adacdf7..ab44c3c 100644
--- a/src/iokit/extensions/tar.py
+++ b/src/iokit/extensions/tar.py
@@ -1,3 +1,5 @@
+__all__ = ["Tar"]
+
 import tarfile
 from collections.abc import Iterable
 from io import BytesIO
@@ -9,19 +11,19 @@
 
 class Tar(State, suffix="tar"):
     def __init__(self, states: Iterable[State], **kwargs: Any):
-        buffer = BytesIO()
-        with tarfile.open(fileobj=buffer, mode="w") as tar_buffer:
-            for state in states:
-                file_data = tarfile.TarInfo(name=str(state.name))
-                file_data.size = state.size
-                file_data.mtime = int(state.time.timestamp())
-                tar_buffer.addfile(fileobj=state.data, tarinfo=file_data)
+        with BytesIO() as buffer:
+            with tarfile.open(fileobj=buffer, mode="w") as tar_buffer:
+                for state in states:
+                    file_data = tarfile.TarInfo(name=str(state.name))
+                    file_data.size = state.size
+                    file_data.mtime = int(state.time.timestamp())
+                    tar_buffer.addfile(fileobj=state.buffer, tarinfo=file_data)
 
-        super().__init__(data=buffer, **kwargs)
+            super().__init__(data=buffer.getvalue(), **kwargs)
 
     def load(self) -> list[State]:
         states: list[State] = []
-        with tarfile.open(fileobj=self.data, mode="r") as tar_buffer:
+        with tarfile.open(fileobj=self.buffer, mode="r") as tar_buffer:
             assert tar_buffer is not None
             for member in tar_buffer.getmembers():
                 if not member.isfile():
diff --git a/src/iokit/extensions/txt.py b/src/iokit/extensions/txt.py
index bf3a22b..bd035f6 100644
--- a/src/iokit/extensions/txt.py
+++ b/src/iokit/extensions/txt.py
@@ -1,3 +1,5 @@
+__all__ = ["Txt"]
+
 from typing import Any
 
 from iokit.state import State
@@ -5,9 +7,7 @@
 
 class Txt(State, suffix="txt"):
     def __init__(self, data: str, **kwargs: Any):
-        if not isinstance(data, str):
-            raise TypeError(f"Expected str, got {type(data).__name__}")
         super().__init__(data=data.encode("utf-8"), **kwargs)
 
     def load(self) -> str:
-        return self.data.getvalue().decode("utf-8")
+        return self.data.decode("utf-8")
diff --git a/src/iokit/extensions/yaml.py b/src/iokit/extensions/yaml.py
index 493013d..a053f42 100644
--- a/src/iokit/extensions/yaml.py
+++ b/src/iokit/extensions/yaml.py
@@ -1,6 +1,4 @@
-__all__ = [
-    "Yaml",
-]
+__all__ = ["Yaml"]
 
 from typing import Any
 
@@ -15,4 +13,4 @@ def __init__(self, data: Any, **kwargs: Any):
         super().__init__(data=data, **kwargs)
 
     def load(self) -> Any:
-        return yaml.safe_load(self.data)
+        return yaml.safe_load(self.buffer)
diff --git a/src/iokit/extensions/zip.py b/src/iokit/extensions/zip.py
index ea69071..8875895 100644
--- a/src/iokit/extensions/zip.py
+++ b/src/iokit/extensions/zip.py
@@ -1,3 +1,5 @@
+__all__ = ["Zip"]
+
 import zipfile
 from collections.abc import Iterable
 from datetime import datetime
@@ -9,16 +11,16 @@
 
 class Zip(State, suffix="zip"):
     def __init__(self, states: Iterable[State], **kwargs: Any):
-        buffer = BytesIO()
-        with zipfile.ZipFile(buffer, mode="w") as zip_buffer:
-            for state in states:
-                zip_buffer.writestr(str(state.name), data=state.data.getvalue())
+        with BytesIO() as buffer:
+            with zipfile.ZipFile(buffer, mode="w") as zip_buffer:
+                for state in states:
+                    zip_buffer.writestr(str(state.name), data=state.data)
 
-        super().__init__(data=buffer, **kwargs)
+            super().__init__(data=buffer.getvalue(), **kwargs)
 
     def load(self) -> list[State]:
         states: list[State] = []
-        with zipfile.ZipFile(self.data, mode="r") as zip_buffer:
+        with zipfile.ZipFile(self.buffer, mode="r") as zip_buffer:
             for file in zip_buffer.namelist():
                 with zip_buffer.open(file) as member_buffer:
                     state = State(
diff --git a/src/iokit/state.py b/src/iokit/state.py
index 48d5081..b8ffadd 100644
--- a/src/iokit/state.py
+++ b/src/iokit/state.py
@@ -16,8 +16,6 @@
 
 from iokit.tools.time import now
 
-Payload = BytesIO | bytes
-
 
 class StateName:
     def __init__(self, name: str):
@@ -70,8 +68,8 @@ class State:
     _suffix: str = ""
     _suffixes: tuple[str, ...] = ("",)
 
-    def __init__(self, data: Payload, name: str | StateName = "", time: datetime | None = None):
-        self._data = BytesIO(data) if isinstance(data, bytes) else data
+    def __init__(self, data: bytes, name: str | StateName = "", time: datetime | None = None):
+        self._data = data
         self._name = StateName.make(name, self._suffix)
         self._time = time or now()
 
@@ -115,13 +113,16 @@ def time(self, value: datetime) -> None:
         self._time = value
 
     @property
-    def data(self) -> BytesIO:
-        self._data.seek(0)
-        return BytesIO(self._data.getvalue())
+    def data(self) -> bytes:
+        return self._data
+
+    @property
+    def buffer(self) -> BytesIO:
+        return BytesIO(self._data)
 
     @property
     def size(self) -> int:
-        return self._data.getbuffer().nbytes
+        return len(self._data)
 
     def __repr__(self) -> str:
         size = naturalsize(self.size, gnu=True)
@@ -148,7 +149,7 @@ def cast(self) -> "State":
 
     def load(self) -> Any:
         if not self.name.suffix:
-            return self.data.getvalue()
+            return self.data
         state = self.cast()
         if type(state) is State:  # pylint: disable=unidiomatic-typecheck
             msg = f"Cannot load state with suffix '{self.name.suffix}'"
diff --git a/src/iokit/storage/local.py b/src/iokit/storage/local.py
index c5274ae..f0b1b01 100644
--- a/src/iokit/storage/local.py
+++ b/src/iokit/storage/local.py
@@ -36,7 +36,7 @@ def save_file(
         raise FileExistsError(msg)
     root.mkdir(parents=parents, exist_ok=True)
     path.parent.mkdir(parents=True, exist_ok=True)
-    path.write_bytes(state.data.getvalue())
+    path.write_bytes(state.data)
     return path
 
 
diff --git a/tests/test_download_file.py b/tests/test_download_file.py
index 615a5c3..703bba6 100644
--- a/tests/test_download_file.py
+++ b/tests/test_download_file.py
@@ -4,4 +4,4 @@
 def test_download_file() -> None:
     uri = "https://raw.githubusercontent.com/rilshok/iokit/main/LICENSE"
     state = download_file(uri)
-    assert "MIT License" in state.data.getvalue().decode("utf-8")
+    assert "MIT License" in state.data.decode("utf-8")
diff --git a/tests/test_encryption.py b/tests/test_encryption.py
index 4da3b96..abc92d9 100644
--- a/tests/test_encryption.py
+++ b/tests/test_encryption.py
@@ -2,7 +2,7 @@
 
 import pytest
 
-from iokit import Encryption, Json
+from iokit import Enc, Json
 
 
 def test_encryption() -> None:
@@ -14,7 +14,7 @@ def test_encryption() -> None:
         "int": 42,
     }
     json = Json(data, name="different")
-    state = Encryption(json, password="pA$sw0Rd", salt="s@lt")
+    state = Enc(json, password="pA$sw0Rd", salt="s@lt")
     state_secret = state.load()
     with pytest.raises(ValueError) as excinfo:
         state_secret.load(password="pA$sw0Rd")
diff --git a/tests/test_json.py b/tests/test_json.py
index 4dba62e..45c24ee 100644
--- a/tests/test_json.py
+++ b/tests/test_json.py
@@ -7,21 +7,21 @@ def test_json_empty() -> None:
     state = Json({}, name="empty")
     assert state.name == "empty.json"
     assert state.size == 2
-    assert state.data.getvalue() == b"{}"
+    assert state.data == b"{}"
     assert not state.load()
 
 
 def test_json_single() -> None:
     state = Json({"key": "value"}, name="single")
     assert state.name == "single.json"
-    assert state.data.getvalue() == b'{"key": "value"}'
+    assert state.data == b'{"key": "value"}'
     assert state.load() == {"key": "value"}
 
 
 def test_json_multiple() -> None:
     state = Json({"first": 1, "second": 2}, name="multiple")
     assert state.name == "multiple.json"
-    assert state.data.getvalue() == b'{"first": 1, "second": 2}'
+    assert state.data == b'{"first": 1, "second": 2}'
     assert state.load() == {"first": 1, "second": 2}
     assert 20 < state.size < 30
 
@@ -48,11 +48,11 @@ def test_json_is_string() -> None:
     state = Json("hello", name="string")
     assert state.load() == "hello"
     assert state.size == 7
-    assert state.data.getvalue() == b'"hello"'
+    assert state.data == b'"hello"'
 
 
 def test_json_is_sequence() -> None:
     state = Json([1, 2, 3], name="sequence")
     assert state.load() == [1, 2, 3]
     assert state.size == 9
-    assert state.data.getvalue() == b"[1, 2, 3]"
+    assert state.data == b"[1, 2, 3]"
diff --git a/tests/test_jsonl.py b/tests/test_jsonl.py
index a308582..782ba99 100644
--- a/tests/test_jsonl.py
+++ b/tests/test_jsonl.py
@@ -5,21 +5,21 @@ def test_jsonl_empty() -> None:
     state = Jsonl([], name="empty")
     assert state.name == "empty.jsonl"
     assert state.size == 0
-    assert state.data.getvalue() == b""
+    assert state.data == b""
     assert not state.load()
 
 
 def test_jsonl_single() -> None:
     state = Jsonl([{"key": "value"}], name="single")
     assert state.name == "single.jsonl"
-    assert state.data.getvalue() == b'{"key":"value"}\n'
+    assert state.data == b'{"key":"value"}\n'
     assert state.load() == [{"key": "value"}]
 
 
 def test_jsonl_multiple_repeat() -> None:
     state = Jsonl([{"key": "value"}] * 2, name="multiple")
     assert state.name == "multiple.jsonl"
-    assert state.data.getvalue() == b'{"key":"value"}\n{"key":"value"}\n'
+    assert state.data == b'{"key":"value"}\n{"key":"value"}\n'
     assert state.load() == [{"key": "value"}] * 2
 
 
diff --git a/tests/test_tar.py b/tests/test_tar.py
index 0577949..b53e884 100644
--- a/tests/test_tar.py
+++ b/tests/test_tar.py
@@ -22,7 +22,7 @@ def test_tar_compress() -> None:
     archive2_gz = Gzip(archive)
 
     assert archive1_gz.size == archive2_gz.size
-    assert archive1_gz.data.getvalue() == archive2_gz.data.getvalue()
+    assert archive1_gz.data == archive2_gz.data
     loaded = archive1_gz.load().load()
     assert find_state(loaded, "text1.txt").load() == "First file"
     assert find_state(loaded, "text2.txt").load() == "Second file"
diff --git a/tests/test_yaml.py b/tests/test_yaml.py
index 069ad5f..42fc1e3 100644
--- a/tests/test_yaml.py
+++ b/tests/test_yaml.py
@@ -5,7 +5,7 @@ def test_yaml_empty() -> None:
     state = Yaml([], name="empty")
     assert state.name == "empty.yaml"
     assert state.size == 3
-    assert state.data.getvalue() == b"[]\n"
+    assert state.data == b"[]\n"
     assert not state.load()