Сертификат настраиваемого сервера .NET Core CA

private static byte[] s_issuingCABytes = { ... };

handler.ServerCertificateCustomValidationCallback +=
    (message, certificate, chain, errors) =>
    {
        const SslPolicyErrors Mask =
#if CA_IS_TRUSTED
            ~SslPolicyErrors.None;
#else
            ~SslPolicyErrors.RemoteCertificateChainErrors;
#endif

        // If a cert is not present, or it didn't match the host.
        // (And if the CA should have been root trusted anyways, also checks that)
        if ((errors & Mask) != SslPolicyErrors.None)
        {
            return false;
        }

        foreach (X509ChainElement element in chain.ChainElements)
        {
            if (element.Certificate.RawData.SequenceEqual(s_issuingCABytes))
            {
                // The expected certificate was found, huzzah!
                return true;
            }
        }

        // The expected cert was not in the chain.
        return false;
    };