I was looking for this in the PeopleBooks and could not find it. Also after searching Google for a bit, I also came up empty. So I thought I would share this with you to save you some time.
PeopleSoft does have a Social Security Number (or rather National ID) masking feature.
Browse to Main Menu > Set Up SACR > Security > Secure Student Administration > Permission List > Demographic Data Access.
Under the *Mask National ID column select Mask entire field from the dropdown. This will mask it for everyone. You can setup additional ones within this window and secure them by primary permission list. Example, you have some people that need to see them and others that don’t.
To apply this change you have to run a process. Browse to Main Menu > Set Up SACR > Security > Secure Student Administration > Process > Demographic Data Access. You now have to create a Run Control ID. I simply named mine, SSN. And click Add.
Then hit OK.
You can then go into the Process Monitor and make sure your request went through successfully.