C#

using System;
using System.DirectoryServices;
using System.Runtime.InteropServices;
 
public sealed class AdsiUtils
{
    private AdsiUtils() {}
    
    [
        ComImport,
        Guid("9068270b-0939-11d1-8be1-00c04fd8d503"),
        InterfaceType(ComInterfaceType.InterfaceIsIDispatch)
    ]
    private interface IADsLargeInteger
    {
        [DispId(2)] int HighPart { get; set; }
        [DispId(3)] int LowPart { get; set; }
    }
    
    public static DateTime AdsDateValue(object value)
    {
        try
        {
            IADsLargeInteger v = value as IADsLargeInteger;
            if (null == v) return DateTime.MinValue;
            
            long dV = ((long)v.HighPart << 32) + (long)v.LowPart;
            return DateTime.FromFileTime(dV);
        }
        catch
        {
            return DateTime.MinValue;
        }
    }
}

IADsLargeInteger v = value as IADsLargeInteger;

Guid objectGuid = new Guid((byte[])entry.Properties["objectGUID"].Value);

[DllImport("kernel32.dll", SetLastError=true)]
private static extern IntPtr LocalFree(IntPtr hMem);
 
[DllImport("advapi32", CharSet=CharSet.Auto, SetLastError=true)]
private static extern bool ConvertSidToStringSid(
    [MarshalAs(UnmanagedType.LPArray)] byte[] pSID, 
    out IntPtr ptrSid);
        
public static string FormatSid(byte[] sid)
{
    if (null == sid || 0 == sid.Length)
        throw new ArgumentNullException("sid");
 
    IntPtr ptrSid;
    if (!ConvertSidToStringSid(sid, out ptrSid))
        throw new System.ComponentModel.Win32Exception();
 
    try
    {
        return Marshal.PtrToStringAuto(ptrSid);
    }
    finally
    {
        LocalFree(ptrSid);
    }
}
...
string objectSid = FormatSid((byte[])entry.Properties["objectSid"].Value);