AddSigningCredential for IdentityServer4

Question

We are using IdentityServer4 with .NET Core Web Application("http://docs.identityserver.io/en/release/quickstarts/0_overview.html"). We have replaced AddDeveloperSigningCredential with AddSigningCredential(CreateSigningCredential()). As we cannot use AddDeveloperSigningCredential for production environment because on production needs to be replaced by some persistent key material. We are new to IdentityServer4 and our question is that, Is following approach fine to create signing credentials on production environment? Or do we need to made some changes in this?

Here is our startup.cs file:

public void ConfigureServices(IServiceCollection services)
{
    services.AddSingleton<IConfiguration>(Configuration);

    //connection string
    string connectionString = Configuration.GetConnectionString("IdentityServer");

    var migrationsAssembly = typeof(Startup).GetTypeInfo().Assembly.GetName().Name;

    services.AddIdentityServer().AddDeveloperSigningCredential
    .AddSigningCredential(CreateSigningCredential())
    // this adds the config data from DB (clients, resources)
    .AddConfigurationStore(options =>
    {
        options.ConfigureDbContext = builder =>
        builder.UseSqlServer(connectionString,
            sql => sql.MigrationsAssembly(migrationsAssembly));
                }) // this adds the operational data from DB (codes, tokens, consents)
    .AddOperationalStore(options =>
    {
        options.ConfigureDbContext = builder =>
        builder.UseSqlServer(connectionString,
            sql => sql.MigrationsAssembly(migrationsAssembly));

        // this enables automatic token cleanup. this is optional.
        options.EnableTokenCleanup = true;
        options.TokenCleanupInterval = 30;
        });
}

private SigningCredentials CreateSigningCredential()
{
    var credentials = new SigningCredentials(GetSecurityKey(), SecurityAlgorithms.RsaSha256Signature);

    return credentials;
}
private RSACryptoServiceProvider GetRSACryptoServiceProvider()
{
    return new RSACryptoServiceProvider(2048);
}
private SecurityKey GetSecurityKey()
{
    return new RsaSecurityKey(GetRSACryptoServiceProvider());
}

Answer 1

Here is a gist that should help for Ids4 with asp.net core 2.x.

It contains an RsaKeyService class that can be injected into the service provider like:

var rsa = new RsaKeyService(Environment, TimeSpan.FromDays(30));
services.AddTransient<RsaKeyService>(provider => rsa);

This makes sure, that an RSA key is used for 30 days at most, before a new one is re-generated.

To use the key, you can call rsa.GetKey(), and to register as a signing credential, use:

builder.AddSigningCredential(rsa.GetKey());