Working from Matt Dekrey's fabulous answer, I've created a fully working example of token-based authentication, working against ASP.NET Core (1.0.1). You can find the full code in this repository on GitHub (alternative branches for 1.0.0-rc1, beta8, beta7), but in brief, the important steps are:
Generate a key for your application
In my example, I generate a random key each time the app starts, you'll need to generate one and store it somewhere and provide it to your application. See this file for how I'm generating a random key and how you might import it from a .json file. As suggested in the comments by @kspearrin, the Data Protection API seems like an ideal candidate for managing the keys "correctly", but I've not worked out if that's possible yet. Please submit a pull request if you work it out!
Startup.cs - ConfigureServices
Here, we need to load a private key for our tokens to be signed with, which we will also use to verify tokens as they are presented. We're storing the key in a class-level variable key which we'll re-use in the Configure method below. TokenAuthOptions is a simple class which holds the signing identity, audience and issuer that we'll need in the TokenController to create our keys.
// Replace this with some sort of loading from config / file. RSAParameters keyParams = RSAKeyUtils.GetRandomKey(); // Create the key, and a set of token options to record signing credentials // using that key, along with the other parameters we will need in the // token controlller. key = new RsaSecurityKey(keyParams); tokenOptions = new TokenAuthOptions() { Audience = TokenAudience, Issuer = TokenIssuer, SigningCredentials = new SigningCredentials(key, SecurityAlgorithms.Sha256Digest) }; // Save the token options into an instance so they're accessible to the // controller. services.AddSingleton<TokenAuthOptions>(tokenOptions); // Enable the use of an [Authorize("Bearer")] attribute on methods and // classes to protect. services.AddAuthorization(auth => { auth.AddPolicy("Bearer", new AuthorizationPolicyBuilder() .AddAuthenticationSchemes(JwtBearerDefaults.AuthenticationScheme) .RequireAuthenticatedUser().Build()); });
We've also set up an authorization policy to allow us to use [Authorize("Bearer")] on the endpoints and classes we wish to protect.
Startup.cs - Configure
Here, we need to configure the JwtBearerAuthentication:
app.UseJwtBearerAuthentication(new JwtBearerOptions { TokenValidationParameters = new TokenValidationParameters { IssuerSigningKey = key, ValidAudience = tokenOptions.Audience, ValidIssuer = tokenOptions.Issuer, // When receiving a token, check that it is still valid. ValidateLifetime = true, // This defines the maximum allowable clock skew - i.e. // provides a tolerance on the token expiry time // when validating the lifetime. As we're creating the tokens // locally and validating them on the same machines which // should have synchronised time, this can be set to zero. // Where external tokens are used, some leeway here could be // useful. ClockSkew = TimeSpan.FromMinutes(0) } });
TokenController
In the token controller, you need to have a method to generate signed keys using the key that was loaded in Startup.cs. We've registered a TokenAuthOptions instance in Startup, so we need to inject that in the constructor for TokenController:
[Route("api/[controller]")] public class TokenController : Controller { private readonly TokenAuthOptions tokenOptions; public TokenController(TokenAuthOptions tokenOptions) { this.tokenOptions = tokenOptions; } ...
Then you'll need to generate the token in your handler for the login endpoint, in my example I'm taking a username and password and validating those using an if statement, but the key thing you need to do is create or load a claims-based identity and generate the token for that:
public class AuthRequest { public string username { get; set; } public string password { get; set; } } /// <summary> /// Request a new token for a given username/password pair. /// </summary> /// <param name="req"></param> /// <returns></returns> [HttpPost] public dynamic Post([FromBody] AuthRequest req) { // Obviously, at this point you need to validate the username and password against whatever system you wish. if ((req.username == "TEST" && req.password == "TEST") || (req.username == "TEST2" && req.password == "TEST")) { DateTime? expires = DateTime.UtcNow.AddMinutes(2); var token = GetToken(req.username, expires); return new { authenticated = true, entityId = 1, token = token, tokenExpires = expires }; } return new { authenticated = false }; } private string GetToken(string user, DateTime? expires) { var handler = new JwtSecurityTokenHandler(); // Here, you should create or look up an identity for the user which is being authenticated. // For now, just creating a simple generic identity. ClaimsIdentity identity = new ClaimsIdentity(new GenericIdentity(user, "TokenAuth"), new[] { new Claim("EntityID", "1", ClaimValueTypes.Integer) }); var securityToken = handler.CreateToken(new Microsoft.IdentityModel.Tokens.SecurityTokenDescriptor() { Issuer = tokenOptions.Issuer, Audience = tokenOptions.Audience, SigningCredentials = tokenOptions.SigningCredentials, Subject = identity, Expires = expires }); return handler.WriteToken(securityToken); }
And that should be it. Just add [Authorize("Bearer")] to any method or class you want to protect, and you should get an error if you attempt to access it without a token present. If you want to return a 401 instead of a 500 error, you'll need to register a custom exception handler as I have in my example here.
