尝试合并三大分支进度

sender/sender.py

@@ -6,12 +6,11 @@ import os
 
 
 from entity.Letter import Letter
-from itsdangerous import base64_encode
 from tool import PriKeyHelper
 from tool.PriKeyHelper import getUserKey
 from tool.asymmetric import RSA
 from tool.symmetric.AES import AESUtils
-from tool.symmetric.SM4 import encrypt_ecb, decrypt_cbc_with_iv, encrypt_cbc_with_iv
+from tool.symmetric.SM4 import encrypt_ecb, encrypt_cbc_with_iv
 from Crypto.Random import get_random_bytes