Restoring a macOS from scratch on to Intel-based MacBook Pro Model A1398 I encountered the error while running "Reinstall macOS":
"This copy of the Install macOS High Sierra application is damaged, and can't be user to install macOS"
This error can be mainly due to the fact that the process running from the recovery has a "date" outside the validity period of a certificate that participates in the recovery process, I do not know if it is from the copy to recover or from the installer. The solution is to play until you put a "date" of the validity period of this certificate, entering the console and executing the following command:
date mmddhhmiyy
Where "mm" is the month, "dd" the day within the month, "hh" is the hour, "mi" the minutes, and "yy" the last two digits of the year.
For example:
date 0328014015
And try again to run the "Reinstall macOS" until you find a correct date.
On the internet you can find pages that give valid dates for different versions of macOS.
This error can surely also occur in a normal recovery, not from scratch of a Mac (for example when Mac has an OS upgrade that does not end well and is corrupt, a situation that has been given to me a couple of times although it seems incredible in an OS of this level), if it is a computer with a certain antiquity. In my case I found it in a total recovery of a Mac that had installed other operating system than a macOS.
