What is a solution for multiple inheritance - with opportunity to change protection?

Question

I need a solution for multiple inheritance. I know that I can use interfaces. That would be good solution but...

I need opportunity to change protection level but fields of interface must be public.

For example:

I have

interface IInterface_1 {
  string field_1{set;get;}
  string field_2{set;get;}
}

interface IInterface_2 {
  string field_3{set;get}
  string field_4{set;get}
}

And in main class I need to hide some fields

class MainClass : IInterface_1, IInterface_2 {
  public string field_1{set;get;}
  private string field_2{set;get;}
  public string field_3{set;get}
  public string field_4{set;get}
}

Do you have any solution for this?

Answer 1

[Copied from Robson's question and his rejected edit to Marc's answer]

My solution is:

public class PermissionDeniedException : Exception {}

class MainClass : IInterface_1, IInterface_2 {
  public string field_1{set;get;}
  private string field_2{set;get;}
  string IInterface_1.field_2 {
    get {throw new PermissionDeniedException();}
    set {throw new PermissionDeniedException();}
  }
  public string field_3{set;get}
  public string field_4{set;get}
}