用了两天的时间研究了在Asp.Net WebApi 项目中如何实现注册、登录、身份验证功能。此项目使用JWT（Json Web Token）来进行身份验证。

用户服务

ASP.NET Core用户服务负责与用户身份验证，注册和管理相关的所有数据库交互和核心业务逻辑。

该文件的顶部包含一个定义用户服务的接口，下面是实现该接口的具体用户服务类。该类的底部包含一些私有方法，用于创建和验证存储在数据库中的散列密码。

1. 通过Emain和Password来登录服务，Authenticate方法调用VerifyPasswordHash来验证Email和密码是否正确来进行登录授权。

public User Authenticate(string email, string password){if (string.IsNullOrEmpty(email) || string.IsNullOrEmpty(password))return null;var user = _iUserRepository.GetUserByEmail(email);// check if username existsif (user == null)return null;// check if password is correctif (!VerifyPasswordHash(password, user.PasswordHash, user.PasswordSalt))return null;// authentication successfulreturn user;}

private static bool VerifyPasswordHash(string password, byte[] storedHash, byte[] storedSalt){if (password == null) throw new ArgumentNullException(nameof(password));if (string.IsNullOrWhiteSpace(password)) throw new ArgumentException("Value cannot be empty or whitespace only string.", "password");if (storedHash.Length != 64) throw new ArgumentException("Invalid length of password hash (64 bytes expected).", "passwordHash");if (storedSalt.Length != 128) throw new ArgumentException("Invalid length of password salt (128 bytes expected).", "passwordHash");using (var hmac = new System.Security.Cryptography.HMACSHA512(storedSalt)){var computedHash = hmac.ComputeHash(System.Text.Encoding.UTF8.GetBytes(password));for (int i = 0; i < computedHash.Length; i++){if (computedHash[i] != storedHash[i]) return false;}}return true;}

1. 用户注册时需要创建新用户并将用户数据存放到数据库中

public User Create(User user, string password){// validationif (string.IsNullOrWhiteSpace(password))throw new AppException("Password is required");if (_iUserRepository.Any(x => x.Email == user.Email))throw new AppException("Email \"" + user.Email + "\" is already taken");if (_iUserRepository.Any(x => x.UserName == user.UserName))throw new AppException("Username \"" + user.UserName + "\" is already taken");CreatePasswordHash(password, out var passwordHash, out var passwordSalt);user.PasswordHash = passwordHash;user.PasswordSalt = passwordSalt;_iUserRepository.Add(user);return user;}

对密码进行加密存储

private static void CreatePasswordHash(string password, out byte[] passwordHash, out byte[] passwordSalt){if (password == null) throw new ArgumentNullException(nameof(password));if (string.IsNullOrWhiteSpace(password)) throw new ArgumentException("Value cannot be empty or whitespace only string.", "password");using (var hmac = new System.Security.Cryptography.HMACSHA512()){passwordSalt = hmac.Key;passwordHash = hmac.ComputeHash(System.Text.Encoding.UTF8.GetBytes(password));}}

3. 用户信息更新及删除代码

public void Update(User userParam, string password = null){var user = _iUserRepository.GetById(userParam.Id);if (user == null)throw new AppException("User not found");if (userParam.UserName != user.UserName){// username has changed so check if the new username is already takenif (_iUserRepository.Any(x => x.UserName == userParam.UserName))throw new AppException("Username " + userParam.UserName + " is already taken");}// update user propertiesuser.FirstName = userParam.FirstName;user.LastName = userParam.LastName;user.UserName = userParam.UserName;// update password if it was enteredif (!string.IsNullOrWhiteSpace(password)){CreatePasswordHash(password, out var passwordHash, out var passwordSalt);user.PasswordHash = passwordHash;user.PasswordSalt = passwordSalt;}_iUserRepository.Update(user);}public void Delete(string id){var user = _iUserRepository.GetById(id);if (user != null){_iUserRepository.Remove(user);}}

用户实体、用户模型及数据上下文

public class User{public string Id { get; set; }public string FirstName { get; set; }public string LastName { get; set; }public string UserName { get; set; }public string Email { get; set; }public byte[] PasswordHash { get; set; }public byte[] PasswordSalt { get; set; }}

public class UserModel{public string Id { get; set; }public string FirstName { get; set; }public string LastName { get; set; }public string UserName { get; set; }public string Email { get; set; }public string Password { get; set; }}

public class VueContext : DbContext{public VueContext(DbContextOptions<VueContext> options): base(options){}public DbSet<User> User { get; set; }}

应用程序设置文件

/appsettings.json

{"AppSettings": {"Secret": "THIS IS USED TO SIGN AND VERIFY JWT TOKENS, REPLACE IT WITH YOUR OWN SECRET, IT CAN BE ANY STRING"},"Logging": {"IncludeScopes": false,"LogLevel": {"Default": "Warning"}},"AllowedHosts": "*","ConnectionStrings": {"VueDatabase": "serverName;Database=VueDb;Trusted_Connection=True;"}
}

在Startup.cs中配置身份验证

添加以下代码到ConfigureServices方法中以添加身份验证服务

// configure strongly typed settings objectsvar appSettingsSection = Configuration.GetSection("AppSettings");services.Configure<AppSettings>(appSettingsSection);// configure jwt authenticationvar appSettings = appSettingsSection.Get<AppSettings>();var key = Encoding.ASCII.GetBytes(appSettings.Secret);services.AddAuthentication(x =>{x.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;x.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;}).AddJwtBearer(x =>{x.Events = new JwtBearerEvents{OnTokenValidated = context =>{var userService = context.HttpContext.RequestServices.GetRequiredService<IUserService>();var userId = context.Principal.Identity.Name;var user = userService.GetById(userId);if (user == null){// return unauthorized if user no longer existscontext.Fail("Unauthorized");}return Task.CompletedTask;}};x.RequireHttpsMetadata = false;x.SaveToken = true;x.TokenValidationParameters = new TokenValidationParameters{ValidateIssuerSigningKey = true,IssuerSigningKey = new SymmetricSecurityKey(key),ValidateIssuer = false,ValidateAudience = false};});

对应用配置身份验证，添加以下代码到Configure中

app.UseAuthentication();

核心代码大概就这些。最近看了微软官方文档，但是并没有发现详细教程，最终发现一篇博客，提取核心内容搬运记录下来。

参考文献

http://jasonwatmore.com/post/2018/06/26/aspnet-core-21-simple-api-for-authentication-registration-and-user-management#user-service-cs

https://neilq.github.io/2018/07/14/secure-your-asp-net-core-2-1-api-1-issuing-a-JWT/

https://www.cnblogs.com/RainingNight/p/jwtbearer-authentication-in-asp-net-core.html