Simple token based authentication/authorization in asp.net core for Mongodb datastore

Let me clarify a little @Adem’s answer. You need to to implement custom middleware in specific way. There is 3 abstract classes that need to be implemented to implementing this (answer is correct for asp.net core rc2btw):

Microsoft.AspNetCore.Builder.AuthenticationOptions
Microsoft.AspNetCore.Authentication.AuthenticationMiddleware<TOptions>
Microsoft.AspNetCore.Authentication.AuthenticationHandler<TOptions>

and then add this middleware to your startup class.

Code example:

public class TokenOptions : AuthenticationOptions
    {
        public TokenOptions() : base()
        {
            AuthenticationScheme = "Bearer";
            AutomaticAuthenticate = true;
        }
    }

public class AuthMiddleware : AuthenticationMiddleware<TokenOptions>
{
    protected override AuthenticationHandler<TokenOptions> CreateHandler()
    {
       return new AuthHandler(new TokenService());
    }

    public AuthMiddleware(RequestDelegate next, IOptions<TokenOptions> options, ILoggerFactory loggerFactory, UrlEncoder encoder) : base(next, options, loggerFactory, encoder)
    {
    }
}

public class AuthHandler : AuthenticationHandler<TokenOptions>
{
    private ITokenService _tokenService;

    public AuthHandler(ITokenService tokenService)
    {
        _tokenService = tokenService;
    }

    protected override async Task<AuthenticateResult> HandleAuthenticateAsync()
    {
        string token = null;
        AuthenticateResult result = null;
        string token = Helper.GetTokenFromHEader(Request.Headers["Authorization"]);
        // If no token found, no further work possible
        if (string.IsNullOrEmpty(token))
        {
            result = AuthenticateResult.Skip();
        }
        else
        {
            bool isValid = await _tokenService.IsValidAsync(token);
            if (isValid)
            {
                //assigning fake identity, just for illustration
                ClaimsIdentity claimsIdentity = new ClaimsIdentity("Custom");
                var claims = new List<Claim>();
                claims.Add(new Claim(ClaimTypes.Name, "admin"));
                claims.Add(new Claim(ClaimTypes.NameIdentifier, "admin"));
                claims.Add(new Claim(ClaimTypes.Role, "admin"));
                ClaimsPrincipal claimsPrincipal = new ClaimsPrincipal(claimsIdentity);
                result =
                    AuthenticateResult.Success(new AuthenticationTicket(claimsPrincipal,
                        new AuthenticationProperties(), Options.AuthenticationScheme));
            }
            else
            {
                result = AuthenticateResult.Skip();
            }
        }

        return result;
    }
}`

p.s. The code is just for illustration of idea. You will need to implement your own handler of course.