设计一个模拟的系统用户安全登录的程序，采用MD5算法实现用户登录口令的安全认证。程序具有注册和登录两个功能，用户注册功能提示用户输入用户名和口令，实现用户名和用户口令的MD5散列值的一一对应。用户登录功能，提示用户输入用户名和口令，用户输入后口令正确，给出合法用户的提示；否则给出非法用户提示。-Design a simulation of the system users safe login procedures, the use of MD5 algorithm to achieve the user login password security certification. The program has two functions: registration and login. The user registration function prompts the user to enter the user name and password, and realize the one-to-one correspondence between the MD5 hash value of the user name and user password. User login function, prompting the user to enter the user name and password, the user input after the password is correct, given the legitimate user prompt　otherwise give the illegal user prompt.