C# 实现简单的登录验证系统

public class LoginSystem
{
    // 模拟数据库存储的用户（密码已用SHA256+盐值加密）
    private static readonly Dictionary<string, (string PasswordHash, string Salt)> _users = new Dictionary<string, (string, string)>
    {
        { "admin", ("e8f69d2c7e5d3a1b0f8e9d7c6b5a493876543210f9e8d7c6b5a493876543210", "salt123") },
        { "user1", ("a1b2c3d4e5f67890a1b2c3d4e5f67890a1b2c3d4e5f67890a1b2c3d4e5f67890", "salt456") }
    };
    // 生成盐值+哈希密码
    private static (string PasswordHash, string Salt) HashPassword(string password)
    {
        string salt = RandomHelper.GetRandomString(6); // 6位随机盐值
        string saltedPassword = password + salt;
        string hash = HashHelper.ComputeSHA256(saltedPassword);
        return (hash, salt);
    }
    // 验证用户名密码
    public static bool Login(string username, string password)
    {
        if (!_users.TryGetValue(username, out var userData))
        {
            Console.WriteLine("用户名不存在！");
            return false;
        }
        // 拼接输入密码和存储的盐值，计算哈希
        string saltedInput = password + userData.Salt;
        string inputHash = HashHelper.ComputeSHA256(saltedInput);
        // 对比哈希值
        bool isSuccess = inputHash == userData.PasswordHash;
        if (isSuccess)
        {
            Console.WriteLine("登录成功！");
        }
        else
        {
            Console.WriteLine("密码错误！");
        }
        return isSuccess;
    }
    // 注册新用户（模拟）
    public static bool Register(string username, string password)
    {
        if (_users.ContainsKey(username))
        {
            Console.WriteLine("用户名已存在！");
            return false;
        }
        var (hash, salt) = HashPassword(password);
        _users.Add(username, (hash, salt));
        Console.WriteLine("注册成功！");
        return true;
    }
    public static void Main(string[] args)
    {
        Console.WriteLine("=== 登录系统 ===");
        Console.Write("请选择操作（1-登录，2-注册）：");
        string choice = Console.ReadLine()?.Trim() ?? "";
        switch (choice)
        {
            case "1":
                Console.Write("请输入用户名：");
                string username = Console.ReadLine()?.Trim() ?? "";
                Console.Write("请输入密码：");
                string password = Console.ReadLine()?.Trim() ?? "";
                Login(username, password);
                break;
            case "2":
                Console.Write("请输入用户名：");
                string newUsername = Console.ReadLine()?.Trim() ?? "";
                Console.Write("请输入密码：");
                string newPassword = Console.ReadLine()?.Trim() ?? "";
                Register(newUsername, newPassword);
                break;
            default:
                Console.WriteLine("无效操作！");
                break;
        }
    }
}