diff --git a/libp2p/io/msgio.py b/libp2p/io/msgio.py
index 38710ff..837f642 100644
--- a/libp2p/io/msgio.py
+++ b/libp2p/io/msgio.py
@@ -5,7 +5,7 @@ from that repo: "a simple package to r/w length-delimited slices."
 
 NOTE: currently missing the capability to indicate lengths by "varint" method.
 """
-# TODO unify w/ https://github.com/libp2p/py-libp2p/blob/1aed52856f56a4b791696bbcbac31b5f9c2e88c9/libp2p/utils.py#L85-L99  # noqa: E501
+
 from typing import Optional
 
 from libp2p.io.abc import MsgReadWriteCloser, Reader, ReadWriteCloser
diff --git a/libp2p/security/insecure/io.py b/libp2p/security/insecure/io.py
deleted file mode 100644
index 1cbff36..0000000
--- a/libp2p/security/insecure/io.py
+++ /dev/null
@@ -1,19 +0,0 @@
-from libp2p.io.abc import MsgReadWriteCloser, ReadWriteCloser
-from libp2p.utils import encode_fixedint_prefixed, read_fixedint_prefixed
-
-
-class PlaintextHandshakeReadWriter(MsgReadWriteCloser):
-    conn: ReadWriteCloser
-
-    def __init__(self, conn: ReadWriteCloser) -> None:
-        self.conn = conn
-
-    async def read_msg(self) -> bytes:
-        return await read_fixedint_prefixed(self.conn)
-
-    async def write_msg(self, msg: bytes) -> None:
-        encoded_msg_bytes = encode_fixedint_prefixed(msg)
-        await self.conn.write(encoded_msg_bytes)
-
-    async def close(self) -> None:
-        await self.conn.close()
diff --git a/libp2p/security/insecure/transport.py b/libp2p/security/insecure/transport.py
index 28e7641..052d342 100644
--- a/libp2p/security/insecure/transport.py
+++ b/libp2p/security/insecure/transport.py
@@ -5,6 +5,7 @@ from libp2p.crypto.keys import PrivateKey, PublicKey
 from libp2p.crypto.pb import crypto_pb2
 from libp2p.crypto.serialization import deserialize_public_key
 from libp2p.io.abc import ReadWriteCloser
+from libp2p.io.msgio import BaseMsgReadWriter
 from libp2p.network.connection.exceptions import RawConnError
 from libp2p.network.connection.raw_connection_interface import IRawConnection
 from libp2p.peer.id import ID
@@ -14,7 +15,6 @@ from libp2p.security.exceptions import HandshakeFailure
 from libp2p.security.secure_conn_interface import ISecureConn
 from libp2p.typing import TProtocol
 
-from .io import PlaintextHandshakeReadWriter
 from .pb import plaintext_pb2
 
 # Reference: https://github.com/libp2p/go-libp2p-core/blob/master/sec/insecure/insecure.go
@@ -22,6 +22,12 @@ from .pb import plaintext_pb2
 
 PLAINTEXT_PROTOCOL_ID = TProtocol("/plaintext/2.0.0")
 
+SIZE_PLAINTEXT_LEN_BYTES = 4
+
+
+class PlaintextHandshakeReadWriter(BaseMsgReadWriter):
+    size_len_bytes = SIZE_PLAINTEXT_LEN_BYTES
+
 
 class InsecureSession(BaseSession):
     def __init__(
diff --git a/libp2p/utils.py b/libp2p/utils.py
index 3d0794a..6493782 100644
--- a/libp2p/utils.py
+++ b/libp2p/utils.py
@@ -78,20 +78,3 @@ async def read_delim(reader: Reader) -> bytes:
             f'`msg_bytes` is not delimited by b"\\n": `msg_bytes`={msg_bytes!r}'
         )
     return msg_bytes[:-1]
-
-
-SIZE_LEN_BYTES = 4
-
-# Fixed-prefixed read/write, used by "/plaintext/2.0.0".
-# Reference: https://github.com/libp2p/go-msgio/blob/d5bbf59d3c4240266b1d2e5df9dc993454c42011/num.go#L11-L33  # noqa: E501  # noqa: E501
-
-
-def encode_fixedint_prefixed(msg_bytes: bytes) -> bytes:
-    len_prefix = len(msg_bytes).to_bytes(SIZE_LEN_BYTES, "big")
-    return len_prefix + msg_bytes
-
-
-async def read_fixedint_prefixed(reader: Reader) -> bytes:
-    len_bytes = await reader.read(SIZE_LEN_BYTES)
-    len_int = int.from_bytes(len_bytes, "big")
-    return await reader.read(len_int)