Are digital signatures using preprocessed paper pads possible? My idea was, given that a computer could produce some sort of lookup tables on paper, could then a human use those lookup tables to create a system for digital signatures?

This was really an idea for fictional writing. I was trying to figure out whether it could be possible in a society at sort of 1950s technology to create a more secure alternative to handwritten signatures.

E.g. that people could order paper pads produced by a computer as service and use those to sign contracts etc with a number rather than a handwritten signature. Another paper pad which was public should be used for verifying the authenticity of the paper.

Could anything like this be done. We assume that given that processing power availability in such a society is much worse than today, this system does not need to be nearly as secure (require as much computation) as today.
The best answer I can come up with is using some sort of Geometric cryptography. It is based on the difficulty of trisecting an angle using a ruler and compass. So you could hand over people a triplet of some secret angle.