How to inject application service into AuthenticationHandler

Question

I have a custom AuthenticationHandler<> implementation that depends on application service. Is there a way to resolve dependencies of AuthenticationHandler from Simple Injector? Or maybe cross-wire registration so that applications services can be resolved from IServiceCollection?

Sample implementation can look as follows for simplicity:

public class AuthHandler : AuthenticationHandler<AuthenticationSchemeOptions>
{
    private readonly ITokenDecryptor tokenDecryptor;

    public SecurityTokenAuthHandler(ITokenDecryptor tokenDecryptor,
        IOptionsMonitor<AuthenticationSchemeOptions> options, 
        ILoggerFactory logger, UrlEncoder encoder, ISystemClock clock) :
        base(options, logger, encoder, clock) =>
        this.tokenDecryptor = tokenDecryptor;

    protected override async Task<AuthenticateResult> HandleAuthenticateAsync() =>
        return tokenDecryptor.Decrypt(this);
}

...

services.AddAuthentication("Scheme")
    .AddScheme<AuthenticationSchemeOptions, AuthHandler>("Scheme", options => { });

Current solution is to manually cross-wire application service which is not quite convenient:

services.AddTransient(provider => container.GetInstance<ITokenDecryptor>());

Answer 1

Tao's answer is right. The easiest way to implement this is to cross wire the AuthHandler to Simple Injector.

This can be done as follows:

// Your original configuration:
services.AddAuthentication("Scheme")
    .AddScheme<AuthenticationSchemeOptions, AuthHandler>("Scheme", options => { });

// Cross wire AuthHandler; let Simple Injector create AuthHandler.
// Note: this must be done after the call to AddScheme. Otherwise it will
// be overridden by ASP.NET.
services.AddTransient(c => container.GetInstance<AuthHandler>());

// Register the handler with its dependencies (in your case ITokenDecryptor) with 
// Simple Injector
container.Register<AuthHandler>();
container.Register<ITokenDecryptor, MyAwesomeTokenDecryptor>(Lifestyle.Singleton);