diff --git a/kasa/klaptransport.py b/kasa/klaptransport.py
index 66052f590..898444c2e 100644
--- a/kasa/klaptransport.py
+++ b/kasa/klaptransport.py
@@ -46,11 +46,12 @@
 import hashlib
 import logging
 import secrets
+import struct
 import time
 from pprint import pformat as pf
 from typing import Any, Dict, Optional, Tuple, cast
 
-from cryptography.hazmat.primitives import hashes, padding
+from cryptography.hazmat.primitives import padding
 from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
 
 from .credentials import Credentials
@@ -66,18 +67,15 @@
 ONE_DAY_SECONDS = 86400
 SESSION_EXPIRE_BUFFER_SECONDS = 60 * 20
 
+PACK_SIGNED_LONG = struct.Struct(">l").pack
+
 
 def _sha256(payload: bytes) -> bytes:
-    digest = hashes.Hash(hashes.SHA256())  # noqa: S303
-    digest.update(payload)
-    hash = digest.finalize()
-    return hash
+    return hashlib.sha256(payload).digest()  # noqa: S324
 
 
 def _sha1(payload: bytes) -> bytes:
-    digest = hashes.Hash(hashes.SHA1())  # noqa: S303
-    digest.update(payload)
-    return digest.finalize()
+    return hashlib.sha1(payload).digest()  # noqa: S324
 
 
 class KlapTransport(BaseTransport):
@@ -426,12 +424,15 @@ class KlapEncryptionSession:
     i.e. sequence number which the device expects to increment.
     """
 
+    _cipher: Cipher
+
     def __init__(self, local_seed, remote_seed, user_hash):
         self.local_seed = local_seed
         self.remote_seed = remote_seed
         self.user_hash = user_hash
         self._key = self._key_derive(local_seed, remote_seed, user_hash)
         (self._iv, self._seq) = self._iv_derive(local_seed, remote_seed, user_hash)
+        self._aes = algorithms.AES(self._key)
         self._sig = self._sig_derive(local_seed, remote_seed, user_hash)
 
     def _key_derive(self, local_seed, remote_seed, user_hash):
@@ -451,31 +452,31 @@ def _sig_derive(self, local_seed, remote_seed, user_hash):
         payload = b"ldk" + local_seed + remote_seed + user_hash
         return hashlib.sha256(payload).digest()[:28]
 
-    def _iv_seq(self):
-        seq = self._seq.to_bytes(4, "big", signed=True)
-        iv = self._iv + seq
-        return iv
+    def _generate_cipher(self):
+        iv_seq = self._iv + PACK_SIGNED_LONG(self._seq)
+        cbc = modes.CBC(iv_seq)
+        self._cipher = Cipher(self._aes, cbc)
 
     def encrypt(self, msg):
         """Encrypt the data and increment the sequence number."""
-        self._seq = self._seq + 1
+        self._seq += 1
+        self._generate_cipher()
+
         if isinstance(msg, str):
             msg = msg.encode("utf-8")
 
-        cipher = Cipher(algorithms.AES(self._key), modes.CBC(self._iv_seq()))
-        encryptor = cipher.encryptor()
+        encryptor = self._cipher.encryptor()
         padder = padding.PKCS7(128).padder()
         padded_data = padder.update(msg) + padder.finalize()
         ciphertext = encryptor.update(padded_data) + encryptor.finalize()
         signature = hashlib.sha256(
-            self._sig + self._seq.to_bytes(4, "big", signed=True) + ciphertext
+            self._sig + PACK_SIGNED_LONG(self._seq) + ciphertext
         ).digest()
         return (signature + ciphertext, self._seq)
 
     def decrypt(self, msg):
         """Decrypt the data."""
-        cipher = Cipher(algorithms.AES(self._key), modes.CBC(self._iv_seq()))
-        decryptor = cipher.decryptor()
+        decryptor = self._cipher.decryptor()
         dp = decryptor.update(msg[32:]) + decryptor.finalize()
         unpadder = padding.PKCS7(128).unpadder()
         plaintextbytes = unpadder.update(dp) + unpadder.finalize()
diff --git a/kasa/protocol.py b/kasa/protocol.py
index 60b3d7ca6..aa9e3cbea 100755
--- a/kasa/protocol.py
+++ b/kasa/protocol.py
@@ -11,6 +11,7 @@
 """
 import base64
 import errno
+import hashlib
 import logging
 import struct
 from abc import ABC, abstractmethod
@@ -18,8 +19,6 @@
 
 # When support for cpython older than 3.11 is dropped
 # async_timeout can be replaced with asyncio.timeout
-from cryptography.hazmat.primitives import hashes
-
 from .credentials import Credentials
 from .deviceconfig import DeviceConfig
 
@@ -29,11 +28,8 @@
 
 
 def md5(payload: bytes) -> bytes:
-    """Return an md5 hash of the payload."""
-    digest = hashes.Hash(hashes.MD5())  # noqa: S303
-    digest.update(payload)
-    hash = digest.finalize()
-    return hash
+    """Return the MD5 hash of the payload."""
+    return hashlib.md5(payload).digest()  # noqa: S324
 
 
 class BaseTransport(ABC):