Did an edit to make it compatible with ASP.NET Core 2.0.
Firstly, some Nuget packages:
- Microsoft.AspNetCore.Authentication.JwtBearer
- Microsoft.AspNetCore.Identity
- System.IdentityModel.Tokens.Jwt
- System.Security.Cryptography.Csp
Then some basic data transfer objects.
// Presumably you will have an equivalent user account class with a user name.
public class User
{
public string UserName { get; set; }
}
public class JsonWebToken
{
public string access_token { get; set; }
public string token_type { get; set; } = "bearer";
public int expires_in { get; set; }
public string refresh_token { get; set; }
}
Getting into the proper functionality, you'll need a login/token web method to actually send the authorization token to the user.
[Route("api/token")]
public class TokenController : Controller
{
private ITokenProvider _tokenProvider;
public TokenController(ITokenProvider tokenProvider) // We'll create this later, don't worry.
{
_tokenProvider = tokenProvider;
}
public JsonWebToken Get([FromQuery] string grant_type, [FromQuery] string username, [FromQuery] string password, [FromQuery] string refresh_token)
{
// Authenticate depending on the grant type.
User user = grant_type == "refresh_token" ? GetUserByToken(refresh_token) : GetUserByCredentials(username, password);
if (user == null)
throw new UnauthorizedAccessException("No!");
int ageInMinutes = 20; // However long you want...
DateTime expiry = DateTime.UtcNow.AddMinutes(ageInMinutes);
var token = new JsonWebToken {
access_token = _tokenProvider.CreateToken(user, expiry),
expires_in = ageInMinutes * 60
};
if (grant_type != "refresh_token")
token.refresh_token = GenerateRefreshToken(user);
return token;
}
private User GetUserByToken(string refreshToken)
{
// TODO: Check token against your database.
if (refreshToken == "test")
return new User { UserName = "test" };
return null;
}
private User GetUserByCredentials(string username, string password)
{
// TODO: Check username/password against your database.
if (username == password)
return new User { UserName = username };
return null;
}
private string GenerateRefreshToken(User user)
{
// TODO: Create and persist a refresh token.
return "test";
}
}
You probably noticed the token creation is still just "magic" passed through by some imaginary ITokenProvider. Define the token provider interface.
public interface ITokenProvider
{
string CreateToken(User user, DateTime expiry);
// TokenValidationParameters is from Microsoft.IdentityModel.Tokens
TokenValidationParameters GetValidationParameters();
}
I implemented the token creation with an RSA security key on a JWT. So...
public class RsaJwtTokenProvider : ITokenProvider
{
private RsaSecurityKey _key;
private string _algorithm;
private string _issuer;
private string _audience;
public RsaJwtTokenProvider(string issuer, string audience, string keyName)
{
var parameters = new CspParameters { KeyContainerName = keyName };
var provider = new RSACryptoServiceProvider(2048, parameters);
_key = new RsaSecurityKey(provider);
_algorithm = SecurityAlgorithms.RsaSha256Signature;
_issuer = issuer;
_audience = audience;
}
public string CreateToken(User user, DateTime expiry)
{
JwtSecurityTokenHandler tokenHandler = new JwtSecurityTokenHandler();
ClaimsIdentity identity = new ClaimsIdentity(new GenericIdentity(user.UserName, "jwt"));
// TODO: Add whatever claims the user may have...
SecurityToken token = tokenHandler.CreateJwtSecurityToken(new SecurityTokenDescriptor
{
Audience = _audience,
Issuer = _issuer,
SigningCredentials = new SigningCredentials(_key, _algorithm),
Expires = expiry.ToUniversalTime(),
Subject = identity
});
return tokenHandler.WriteToken(token);
}
public TokenValidationParameters GetValidationParameters()
{
return new TokenValidationParameters
{
IssuerSigningKey = _key,
ValidAudience = _audience,
ValidIssuer = _issuer,
ValidateLifetime = true,
ClockSkew = TimeSpan.FromSeconds(0) // Identity and resource servers are the same.
};
}
}
So you're now generating tokens. Time to actually validate them and wire it up. Go to your Startup.cs.
In ConfigureServices()
var tokenProvider = new RsaJwtTokenProvider("issuer", "audience", "mykeyname");
services.AddSingleton<ITokenProvider>(tokenProvider);
services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
.AddJwtBearer(options => {
options.RequireHttpsMetadata = false;
options.TokenValidationParameters = tokenProvider.GetValidationParameters();
});
// This is for the [Authorize] attributes.
services.AddAuthorization(auth => {
auth.DefaultPolicy = new AuthorizationPolicyBuilder()
.AddAuthenticationSchemes(JwtBearerDefaults.AuthenticationScheme)
.RequireAuthenticatedUser()
.Build();
});
Then Configure()
public void Configure(IApplicationBuilder app)
{
app.UseAuthentication();
// Whatever else you're putting in here...
app.UseMvc();
}
That should be about all you need. Hopefully I haven't missed anything.
The happy result is...
[Authorize] // Yay!
[Route("api/values")]
public class ValuesController : Controller
{
// ...
}
