I think that people, in general, ought to be able to use general purpose computers. In fact, I think it would be a grave moral evil to disallow people to use them, in most circumstances.
Why should one believe something like this?
First, assume that God exists and Aristotelian-Thomist metaphysics is true. It follows from this that the natural law exists. I’m not going to justify these assumptions. That isn’t the purpose of this post.
Second, assume that people are morally obligated to know things, and to further their knowledge of things. Why should you believe this? There are various ways of motivating this belief. One way would be to say that ignorance is a privation, privations are bad, and so, the less ignorant we are, the less bad we are, i.e., the more we know, the more perfect we become. So, knowing things is good, and knowing more things is better.
Third, assume that a general purpose computer is functionally equivalent to a man following a set of rules that allows him to further his knowledge by use of the rules, i.e. a general purpose computer isn’t doing anything above or beyond what a man is doing when he’s writing a proof.
Finally, assume that it’s not the case that it would be contrary to the natural law to disallow people the use of general purpose computers. But if this was the case, then it wouldn’t be contrary to the natural law to disallow people to follow rules that allow them to further their knowledge by use of the rules, but then it wouldn’t be contrary to the natural law to disallow people to write proofs, but then it wouldn’t be contrary to the natural law to keep people from eliminating their ignorance, but then it wouldn’t be contrary to the natural law to inhibit people’s moral perfection, but God wills people to be morally perfected, and so, it’s contrary to the natural law to disallow people the use of general purpose computers.
One direct consequence of this, in conjunction with the assumption that it is pleasing to God for some things to be kept in confidence, is that we are morally obligated to use, and allow the ability to use, encrypted means of communication, in those circumstances that justify it.