GetMachineKeyConfiguration.cs

namespace MyWebApp
{
    using System;
    using System.Collections.Generic;
    using System.Configuration;
    using System.Linq;
    using System.Reflection;
    using System.Text;
    using System.Web.Configuration;
    using System.Web.Mvc;

    public class SystemController : Controller
    {
        public ActionResult GetMachineKeyConfiguration()
        {
            var section = (MachineKeySection)ConfigurationManager.GetSection("system.web/machineKey");

            var flags = BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.GetProperty;

            Func<string, byte[]> propertyReader =
                name => (byte[])section.GetType().GetProperty(name, flags).GetValue(section, null);

            var decryptionKey = ConvertToHex(propertyReader("DecryptionKeyInternal"));
            var validationKey = ConvertToHex(propertyReader("ValidationKeyInternal"));

            var output = new StringBuilder();
            output.AppendLine(section.Validation.ToString());
            output.AppendLine(validationKey);
            output.AppendLine(section.Decryption);
            output.AppendLine(decryptionKey);

            return this.Content(output.ToString());
        }

        private static string ConvertToHex(IEnumerable<byte> binary)
        {
            return binary.Aggregate(new StringBuilder(), (acc, c) => acc.AppendFormat("{0:x2}", c), acc => acc.ToString());
        }
    }
}