changing lots of file dates?

[rikona]

I had to do a restore of lots of data files back a bit, from a backup
disk. That did restore the files, but for some reason the 'modified'
date for all these files got set to a date way in the past - way earlier
than the 'create' date. May be 100K files or so. That backup no longer
exists, so I can't 'redo' the restore to fix the problem.

Is there a way to SAFELY reset all these on the disk using the
following conditions:
(1) if the modified date is earlier than the create date, set the mod
date to the create date.
(2) if the modified date is later than or = to the
create date, do not change the mod date.
(3) do not change any other date, and don't make the mod or access date
the date when this was done.