When it comes to opening or editing encrypted PowerPoint files, the best option for recovering lost passwords is always Free Download Passper for PowerPoint, a full version standalone offline installer for Windows.
Overview of Passper for PowerPoint: Retrieve forgotten or lost PowerPoint passwords without compromising the PowerPoint information. Read-only PowerPoint files can have their limitations removed so that you can edit, copy, and print them.
Passper for PowerPoint’s features
Retrieve Opening Passwords for PowerPoint and Unlock PowerPoint file that can be read only Dictionary attack Mask attack Combination attack
Brute-Force Offensive
Technical Specifications and System Prerequisites
Operating systems supported: Windows 11, Windows 10, Windows 8.1, and Windows 7.
RAM: 2 GB of RAM (memory); 4 GB is advised.
200 MB or more of free hard disk space