用户注册和登陆系统，采用hmac加密密码（就地txt存储版本）

import hashlib
import pickle, os
import hmac, random


def hmac_sha1(key, s):
    return hmac.new(key.encode('utf-8'), s.encode('utf-8'), 'MD5').hexdigest()


# 获取用户名和密码信息
if os.path.exists('/Users/lewisliu/user_information.txt'):
    with open('/Users/lewisliu/user_information.txt', 'rb') as f:
        user_information = pickle.load(f)
else:
    user_information = dict()

# 注册或者登陆
while True:
    # 选择模式，注册、登陆、退出
    model = input("pleas input enroll/login/exit:")
    if model == 'enroll':
        name = input("please input your name:")
        # 用户名重复识别
        if name in user_information.keys():
            print("name is occupied!")
            continue
        password = input("please input your password:")
        # 数据库添加用户名和密码
        key = 'liu' # ''.join([chr(random.randint(48, 122)) for i in range(20)])
        user_information[name] = hmac_sha1(key, password)
        # sha1 = hashlib.sha1()
        # sha1.update(password.encode('utf-8'))
        # user_information[name] = sha1.hexdigest()
    elif model == 'login':
        name = input("please input your name:")
        if name not in user_information.keys():
            print("name is not exist!")
            continue
        password = input("please input your password:")
        key = 'liu' # ''.join([chr(random.randint(48, 122)) for i in range(20)])
        password = hmac_sha1(key, password)
        # sha1 = hashlib.sha1()
        # sha1.update(password.encode('utf-8'))
        # password = sha1.hexdigest()
        if user_information[name] == password:
            print("Wellcome!")
        else:
            print("wrong name or password! Exit!")
            with open('/Users/lewisliu/user_information.txt', 'wb') as f:
                pickle.dump(user_information, f)
            exit()
    elif model == 'exit':
        with open('/Users/lewisliu/user_information.txt', 'wb') as f:
            pickle.dump(user_information, f)
        exit()
    else:
        print("model wrong!")