How hard is this to hack? The first observation is that the system is entirely manual, making it immune to the sorts of technological attacks that make modern voting systems so risky. The second observation is that the small group of voters — all of whom know each other — makes it impossible for an outsider to affect the voting in any way. The chapel is cleared and locked before voting. No one is going to dress up as a cardinal and sneak into the Sistine Chapel. In effect, the voter verification process is about as perfect as you’re ever going to find.
In summary, it’s far harder to fix the election of a new Pope, and Schneier goes into glorious detail.
Photo credit: magamaps.