diff --git a/aesDrbg.py b/aesDrbg.py
index 9fe0d41..b6bf9f1 100755
--- a/aesDrbg.py
+++ b/aesDrbg.py
@@ -26,13 +26,13 @@ class AES_CTR_DRBG:
         # 最大的熵输入长度
         self.max_ectropy_input_length = 1 << 35 - 1  # 2^35比特
 
-        self.seed_material = ""
+        self.seed_material = b""
         self.aes = AES.new(b"\x00" * self.keylen, AES.MODE_ECB)
         self.AES_CTR_DRBG_Instantiate(personalization_string, nonce)
 
     def AES_CTR_DRBG_Instantiate(
         self, personalization_string: bytes = b"", nonce: bytes = b""
-    ):
+    )-> None:
         self.min_entropy = self.seedlen
         self.entropy_input = secrets.token_bytes(self.min_entropy)
         self.seed_material = self.entropy_input + nonce + personalization_string
@@ -42,11 +42,11 @@ class AES_CTR_DRBG:
         self.reseed_counter = 1
         self.last_reseed_time = int(time.time())
 
-    def AES_CTR_DRBG_Update(self, seed_material, Key, V):
+    def AES_CTR_DRBG_Update(self, seed_material:bytes, Key:bytes, V: bytes)->None:
         temp = b""
         while len(temp) < len(seed_material):
-            self.V = (int.from_bytes(self.V, "big") + 1) % (1 << (8 * self.blocklen))
-            self.V = self.V.to_bytes(self.blocklen, "big")
+            V_int = (int.from_bytes(self.V, "big") + 1) % (1 << (8 * self.blocklen))
+            self.V = V_int.to_bytes(self.blocklen, "big")
             temp += self.aes.encrypt(self.V)
         temp = temp[: len(seed_material)]
         temp = int.from_bytes(temp, "big") ^ int.from_bytes(seed_material, "big")
@@ -78,7 +78,7 @@ class AES_CTR_DRBG:
         requested_bits = tmp[:number_of_bits_to_return]
         return requested_bits
 
-    def CBC_MAC(self, Key, data_to_MAC):
+    def CBC_MAC(self, Key: bytes, data_to_MAC:bytes)->bytes:
         chaining_value = b"\x00" * self.blocklen
         for i in range(0, len(data_to_MAC), self.blocklen):
             block = data_to_MAC[i : i + self.blocklen]
@@ -90,7 +90,7 @@ class AES_CTR_DRBG:
             )
         return chaining_value
 
-    def AES_CTR_DRBG_Reseed(self, additional_input: bytes):
+    def AES_CTR_DRBG_Reseed(self, additional_input: bytes)-> None:
         self.min_entropy = self.seedlen
         self.entropy_input = secrets.token_bytes(self.min_entropy)
         self.seed_material = self.entropy_input + additional_input
@@ -100,8 +100,8 @@ class AES_CTR_DRBG:
         self.last_reseed_time = int(time.time())
 
     def AES_CTR_DRBG_Generate(
-        self, requested_number_of_bits, additional_input: bytes = b""
-    ):
+        self, requested_number_of_bits: int, additional_input: bytes = b""
+    )-> bytes:
         length = requested_number_of_bits // 8
         returned_bits = b""
         if (
@@ -115,8 +115,8 @@ class AES_CTR_DRBG:
         else:
             additional_input = b"\x00" * self.seedlen
         while len(returned_bits) < length:
-            self.V = (int.from_bytes(self.V, "big") + 1) % (1 << (8 * self.blocklen))
-            self.V = self.V.to_bytes(self.blocklen, "big")
+            V_int = (int.from_bytes(self.V, "big") + 1) % (1 << (8 * self.blocklen))
+            self.V = V_int.to_bytes(self.blocklen, "big")
             output_block = self.aes.encrypt(self.V)
             returned_bits += output_block
         self.AES_CTR_DRBG_Update(additional_input, self.Key, self.V)