Change ServicePointManager.SecurityProtocol through configuration appsettings

App.config

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <appSettings>
    <add key="SecurityProtocol.Remove" value="Ssl3,Tls" />
    <add key="SecurityProtocol.Add" value="Tls11,Tls12" />
  </appSettings>
</configuration>

ConfigureSecurityProtocols.cs

using System.Net;
using System.Configuration;
using System;
using System.Linq;

public static class ConfigureSecurityProtocols
{
    public static void Configure()
    {
        RemoveSecurityProtocols();
        AddSecurityProtocols();
    }

    private static void RemoveSecurityProtocols()
    {
        var securityProtocolsToRemove = ConfigurationManager.AppSettings["SecurityProtocol.Remove"]
            ?.Split(',')
            .Select(o => o.Trim());

        if (securityProtocolsToRemove == null)
        {
            return;
        }

        foreach(var securityProtocolString in securityProtocolsToRemove)
        {
            SecurityProtocolType securityProtocolEnum;
            if (Enum.TryParse(securityProtocolString, out securityProtocolEnum)){
                // removes security protocol using binary operation
                ServicePointManager.SecurityProtocol &= ~securityProtocolEnum;
            }
        }
    }

    private static void AddSecurityProtocols()
    {
        var securityProtocolsAdd = ConfigurationManager.AppSettings["SecurityProtocol.Add"]
            ?.Split(',')
            .Select(o => o.Trim());

        if (securityProtocolsAdd == null)
        {
            return;
        }

        foreach (var securityProtocolString in securityProtocolsAdd)
        {
            SecurityProtocolType securityProtocolEnum;
            if (Enum.TryParse(securityProtocolString, out securityProtocolEnum))
            {
                // adds security protocol using binary operation
                ServicePointManager.SecurityProtocol |= securityProtocolEnum;
            }
        }
    }
}