.NET Framework WebApi Bearer Token Decode

MachineKeyProtector.cs

public class MachineKeyProtector : IDataProtector
{
  private readonly string[] _purpose =
  {
    typeof(OAuthAuthorizationServerMiddleware).Namespace,
    "Access_Token",
    "v1"
  };
  
  public byte[] Protect(byte[] userData)
  {
    throw new NotImplementedException();
  }
  
  public byte[] Unprotect(byte[] protectedData)
  {
    return System.Web.Security.MachineKey.Unprotect(protectedData, _purpose);
  }
}

TokenUtils.cs

public class TokenUtils
{
  public static AuthenticationTicket DecodeBearerToken(string token)
  {
    var secureDataFormat = new TicketDataFormat(new MachineKeyProtector());
    AuthenticationTicket ticket = secureDataFormat.Unprotect(token);
    return ticket;
  }
}