Startup.cs

using System.Collections.Generic;
using System.Linq;
using System.Text;
using Api.DataProviders;
using Api.Models;
using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.IdentityModel.Tokens;
using Swashbuckle.AspNetCore.Swagger;

namespace API
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
            var config = configuration.GetSection("ConfidentialInfo");
            SecretKey = config.GetValue<string>("TokenSecretKey");
        }

        public IConfiguration Configuration { get; }
        public string SecretKey { get; set; }
        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddTransient<UserDataProvider>();
            services.Configure<ConfidentialInfo>(Configuration.GetSection("ConfidentialInfo"));

            services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme).AddJwtBearer(options =>
            {
                options.TokenValidationParameters = new TokenValidationParameters
                {
                    ValidateIssuer = true,
                    ValidateAudience = true,
                    ValidateIssuerSigningKey = true,
                    ValidIssuer = "www.pablogramajo.com",
                    ValidAudience = "www.pablogramajo.com",
                    IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(SecretKey))
                };
            });

            services.AddCors(options =>
            {
                options.AddPolicy("CorsPolicy",
                    builder => builder.AllowAnyOrigin()
                      .AllowAnyMethod()
                      .AllowAnyHeader()
                      .AllowCredentials()
                .Build());
            });

            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new Info { Title = "pablogramajo API", Version = "v1" });
                c.AddSecurityDefinition("Bearer", new ApiKeyScheme
                {
                    In = "header",
                    Description = "Please use this formula: 'Bearer + space + JWT' <br> For Example: Bearer xxxxxxxx",
                    Name = "Authorization",
                    Type = "apiKey"
                }
                );
                c.AddSecurityRequirement(new Dictionary<string, IEnumerable<string>> {
                    { "Bearer", Enumerable.Empty<string>() },
                });
            });
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseHsts();
            }
            app.UseAuthentication();
            app.UseCors("CorsPolicy");
            app.UseSwagger();
            app.UseSwaggerUI(c =>
            {
                c.SwaggerEndpoint("/swagger/v1/swagger.json", "pablogramajo API V1");
                c.RoutePrefix = string.Empty;
            });
            app.UseHttpsRedirection();
            app.UseMvc();
        }
    }
}