Startup.cs

public void ConfigureServices(IServiceCollection services)
{
    services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
            .AddJwtBearer(options => {
                options.TokenValidationParameters = new TokenValidationParameters
                {
                    ValidateIssuer = true,
                    ValidateAudience = true,
                    ValidateLifetime = true,
                    ValidateIssuerSigningKey = true,
                    ValidIssuer = "stephanybatista.com",
                    ValidAudience = "stephanybatista.com",
                    IssuerSigningKey = JwtSecurityKey.Create("a-password-very-big-to-be-good")
                };

                options.Events = new JwtBearerEvents
                {
                    OnAuthenticationFailed = context =>
                    {
                        Console.WriteLine("OnAuthenticationFailed: " + context.Exception.Message);
                        return Task.CompletedTask;
                    },
                    OnTokenValidated = context =>
                    {
                        Console.WriteLine("OnTokenValidated: " + context.SecurityToken);
                        return Task.CompletedTask;
                    }
                };
            });

    services.AddMvc();
}

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    if (env.IsDevelopment())
        app.UseDeveloperExceptionPage();

    app.UseAuthentication();
    app.UseMvc();
}