diff --git a/packages/nonebot-adapter-feishu/nonebot/adapters/feishu/utils.py b/packages/nonebot-adapter-feishu/nonebot/adapters/feishu/utils.py
new file mode 100644
index 00000000..34750255
--- /dev/null
+++ b/packages/nonebot-adapter-feishu/nonebot/adapters/feishu/utils.py
@@ -0,0 +1,33 @@
+import base64
+import hashlib
+
+from Crypto.Cipher import AES
+from nonebot.utils import logger_wrapper
+
+log = logger_wrapper("FEISHU")
+
+class AESCipher(object):
+
+    def __init__(self, key):
+        self.block_size = AES.block_size
+        self.key = hashlib.sha256(AESCipher.str_to_bytes(key)).digest()
+
+    @staticmethod
+    def str_to_bytes(data):
+        u_type = type(b"".decode('utf8'))
+        if isinstance(data, u_type):
+            return data.encode('utf8')
+        return data
+
+    @staticmethod
+    def _unpad(s):
+        return s[:-ord(s[len(s) - 1:])]
+
+    def decrypt(self, enc):
+        iv = enc[:AES.block_size]
+        cipher = AES.new(self.key, AES.MODE_CBC, iv)
+        return self._unpad(cipher.decrypt(enc[AES.block_size:]))
+
+    def decrypt_string(self, enc):
+        enc = base64.b64decode(enc)
+        return self.decrypt(enc).decode('utf8')