aes文件，sender加密方法和模式选择

sender/sender.py

@@ -1,4 +1,7 @@
+# 模式，文件，自己的公钥从哪里来，别人的公钥从哪里来
 from entity.Letter import Letter
+from tool.symmetric.AES import AESUtils
+
 
 def main():
     # 用户输入各种数据填充letter字段
@@ -6,6 +9,56 @@ def main():
     # 使用对方的公钥进行加密
     # 发送信件
     pass
+
+
 def sendLetter(letter: Letter, target="192.168.195.162:8426"):
     # 向目标ip和端口发送指定的信件
     pass
+
+# 选择对称加密的方法和模式(aes/sm2)
+def selectSymEncryptionChoice():
+    encryWay = ""
+    encryMode = ""
+
+    # 选择加密算法
+    while True:
+        encryWay = input("Choose the way for encryption (aes/sm2): ").strip().lower()  # 统一转成小写
+        if encryWay in ["aes", "sm2"]:
+            print(f"You have selected '{encryWay}' encryption.")
+            break  # 输入有效后退出循环
+        else:
+            print("Invalid choice. Please enter 'aes' or 'sm2'.")
+
+    # 选择加密算法的模式
+    while True:
+        if encryWay == "aes":
+            encryMode = input("Choose the encryption mode (ecb/cbc/cfb/ofb): ").strip().lower()
+            if encryMode in ["ecb", "cbc", "cfb", "ofb"]:
+                print(f"You have selected '{encryMode}' encryption mode.")
+                break  # 输入有效后退出循环
+            else:
+                print("Invalid choice. Please enter ecb/cbc/cfb/ofb")
+
+        elif encryWay == "sm2":
+            print()
+            break  # 输入有效后退出循环
+
+    return encryWay, encryMode
+
+
+# 使用对称加密，返回加密后的数据和随机生成的密钥
+def SymEncryption():
+
+    # 获得加密的方法和加密的模式
+    way, mode = selectSymEncryptionChoice()
+
+    if way == "aes":
+        aesUtils = AESUtils()
+        encryptedData, key = aesUtils.encrypt("test", mode=mode) # 这里data要改为文件内容
+        return encryptedData
+
+    if way == "sm2":
+        pass
+
+def getKey():
+    pass

tool/symmetric/AES.py

@@ -0,0 +1,35 @@
+# "ecb", "cbc", "cfb", "ofb"
+
+from Crypto.Cipher import AES
+from Crypto.Util.Padding import pad, unpad
+from Crypto.Random import get_random_bytes
+import base64
+
+class AESUtils:
+    def __init__(self, key: bytes = None):
+        """初始化 AES 加密工具，如果没有提供密钥，则生成一个随机密钥"""
+        if key is None:
+            self.key = get_random_bytes(32)  # AES-256
+        else:
+            self.key = key
+
+    def encrypt(self, data: str, mode: str = 'ECB') -> str:
+        """加密数据"""
+        cipher = self._get_cipher(mode)
+        data = pad(data.encode(), AES.block_size)  # 填充数据
+        ciphertext = cipher.encrypt(data)
+        return base64.b64encode(ciphertext).decode()
+
+    def _get_cipher(self, mode: str) -> AES:
+        """根据模式返回相应的 AES cipher"""
+        iv = None
+        if mode == 'CBC':
+            iv = get_random_bytes(AES.block_size)
+            return AES.new(self.key, AES.MODE_CBC, iv), self.key
+        elif mode == 'CFB':
+            return AES.new(self.key, AES.MODE_CFB), self.key
+        elif mode == 'OFB':
+            return AES.new(self.key, AES.MODE_OFB), self.key
+        else:  # 默认是 ECB
+            return AES.new(self.key, AES.MODE_ECB), self.key
+