My customer wants me to supply them with logos that are "locked" so that when they are imported into a document they can't be stretched/resized. Is that possible?
To add to Andrew's reply, JPG is already "locked", in a way. So, technically, the file is not a working file if saved in a medium to small size. JPG is a lossy compressed file format, and stretching it will just cause artefacts that will eventually make the image look pretty terrible.
You will probably provide your client with at least two formats for the logo: One scalable (vector, say), and one non-scalable (JPG, PNG). You could tell them to use the JPG/PNG for distribution and keep the scalable logo for internal/official use only.
The logo can be available only as an insertable object that has built-in smartiness (= carries some programmed code). No JPG logo anywhere.This belongs to programmer's sphere of influence. It's not manageable by low profile system administrators or by graphic designers. But it works, if it's supported by company management and the staff already is prohibited to make system changes by policies.
Good policies protect the system but cause easily angriness. Even 10 years ago it was quite irritating to have a password asking dialog under my nose nearly every time when I had got some idea.