using System;

​

public class Program {

    public enum EntityTypeId { JobManagement = 1, DocumentFolder = 2 }

    // Represents a composite key on 64 bits (long) where the high 32 bits

    // is the type of the entity and the low 32 bits is the unique identifier of the entity.

    // This could be passed into SenseNet Security if we replace int IDs with long: https://github.com/SenseNet/sn-security

    public readonly struct EntityCompositeId {

        public int TypeId { get; }

        public int Id { get; }      

        public long CompositeId => ((long)TypeId << 32) | (Id & 0x_00000000_ffffffff);

        public EntityCompositeId(int typeId, int id) { TypeId = typeId; Id = id; }

        public static explicit operator long(EntityCompositeId id) => id.CompositeId;

    }

​

    public static void Main() {

        var jobManagement = new { Id = 10 }; // Represents a system permission (placeholder entity) in the Db.

        var documentFolder = new { Id = 1000 }; // Represents a concrete project folder entity in the Db.

        // Generate some composite keys merging both type and entity id into one long id.

        var compKey1 = (long)(new EntityCompositeId((int)EntityTypeId.JobManagement, jobManagement.Id));    

        var compKey2 = (long)(new EntityCompositeId((int)EntityTypeId.DocumentFolder, documentFolder.Id));      

        var compKey3 = (long)(new EntityCompositeId(int.MaxValue, int.MaxValue));

        var compKey4 = (long)(new EntityCompositeId(-int.MaxValue, -int.MaxValue));

        Console.WriteLine("{0,15}{1,65}", nameof(EntityTypeId.JobManagement), ToBinary(compKey1));

        Console.WriteLine("{0,15}{1,65}", nameof(EntityTypeId.DocumentFolder), ToBinary(compKey2));

        Console.WriteLine("{0,15}{1,65}", "Positive max", ToBinary(compKey3)); // sign bit = 0

        Console.WriteLine("{0,15}{1,65}", "Negative max", ToBinary(compKey4)); // sign bit = 1

        static string ToBinary(long value)

            => Convert.ToString(value, 2).PadLeft(sizeof(long) * 8, '0');

    }       

}

​