Prophylaxis Plus is a program that forces the user to enter a password
whenever the Mac is turned on. It's simple and effective startup
security; most users can't bypass it, but it's not impossible (or even
that difficult) for a determined hacker to defeat Prophylaxis Plus.
The only way that I have found to bypass it is to start from a
different System file, such as that on a System disk, so if you lock
your floppy drive, or are convinced that your enemy doesn't carry Mac
System Disks around, it's probably pretty good protection even from
that determined hacker.

First DL is Prophylaxis Plus v1.1
Second DL is Prophylaxis v1.0

Compatibility
Architecture: 68k