3

All NT-based versions of Windows since 2000 have a feature called Encrypting File System (EFS), although "Home" and similarly low-end editions can't use it. You can look up more information about this feature from Microsoft as well, but here are some relevant ones: Encryption and decryption is transparent; keys are managed by the OS and used automatically ...


1

If the ZIP file only holds that one TXT file, then I'm afraid chances of recovery are low. Try visually inspecting the file's hex dump. A "true", undamaged ZIP file should contain high-entropy, random values (all the more so if it's encrypted too). If there are large swaths of repeated filler characters (0x00, 0xC0, 0xA9, 0xFF...), then that section of file ...


Only top voted, non community-wiki answers of a minimum length are eligible