How to Print a Secret

Date Added: Jul 2009
Format: PDF

The authors consider the problem of how to print a human-readable message, or image, on a piece of paper, while simultaneously preventing the participating printing agents or devices from learning its contents. They examine the problem in two set-tings: with a trusted dealer who knows the message, and in a distributed scenario that allows two non-colluding printers to obliviously generate the secret message and print it without ever learning it. They present a basic protocol for printing arbitrary-length messages in the trusted dealer model, as well as protocols for printing different types of messages in the distributed model: a randomly selected element from a set, a random permutation of elements in a set, and an optimization for printing alphanumeric characters using 16- segment display logic.