roobarb: If the audience is a select group then a Non-Disclosure Agreement may be simplest.

Don't try and fool them with 'Security Theatre' that doesn't stand up to scrutiny if you are trying to impress them about security.

NDAs are standard procedure of course.  And I'm beginning to think you're right.

The security issue that you are trying to resolve is not about preventing authorised and legitimate users from stealing the info. There is nothing you can do to prevent them from cheating/stealing as an NDA is like any other contract, it is the meeting of minds or mutual assent that provides compliance and security.

It seems that what you are trying to do is to ensure that non-authorised and illegitimate users cannot access the information provided the authorised users adhere to the NDA and comply with your standard procedure. A secure system provides a level of assurance for your authorised users that is not available without the additional security.