Bdtjtk

I have jwt authentication in my application,
this is how i implemented in my startup.cs class

services.AddAuthentication()

            .AddJwtBearer(options =>

            {

                options.TokenValidationParameters = new TokenValidationParameters

                {

                    ValidateIssuerSigningKey = true,

                    IssuerSigningKey = new SymmetricSecurityKey(Encoding.ASCII

                        .GetBytes(Configuration.GetSection("AppSettings:Token").Value)),

                    ValidateIssuer = false,

                    ValidateAudience = false

                };



            });

inside Configure method

app.UseAuthentication();

in controllers used attribute

[Authorize]

Normal authentication works fine.
I want to check some custom things when authenticating without losing the default authentication process, what I mean by that I don't want to write my whole new authentication method.

You should be able to build on top the default authentication by just chaining authentication schemes.

Firstly, you can implement custom authentication handler:

public class CustomAuthenticationHandler : AuthenticationHandler<CustomAuthHandlerOptions>

{

    public CustomAuthenticationHandler(IOptionsMonitor<CustomAuthHandlerOptions> options, ILoggerFactory logger, UrlEncoder encoder, ISystemClock clock) : base(options, logger, encoder, clock)

    {

    }



    protected override async Task<AuthenticateResult> HandleAuthenticateAsync()

    {

        //Write custom logic here

        return await Context.AuthenticateAsync(Scheme.Name);

    }

}



public class CustomAuthHandlerOptions : AuthenticationSchemeOptions

{

    public string MyCustomOptionsProp { get; set; }

}

And then you can add the scheme to the AuthenticationBuilder:

        services.AddAuthentication()

            .AddJwtBearer(options =>

            {

                options.TokenValidationParameters = new TokenValidationParameters

                {

                    ValidateIssuerSigningKey = true,

                    IssuerSigningKey = new SymmetricSecurityKey(Encoding.ASCII

                        .GetBytes(Configuration.GetSection("AppSettings:Token").Value)),

                    ValidateIssuer = false,

                    ValidateAudience = false

                };



            })

            .AddScheme<CustomAuthHandlerOptions, CustomAuthenticationHandler>("CustomAuthJwt", options =>

                {

                    options.MyCustomOptionsProp = "Custom Value";

                });

I haven't actually tested this, but I know the idea of this approach works because it has been implemented in the IdentityServer4.AccessTokenValidation Nuget Package. My example is just the most simple version of that.