"All crypto is economics," and this is what made seals and sealing wax so useful for so long. Saying "seals were duplicatable from the start" does not mean this feat was easy, even if technically possible.
In fact, the fine details produced by a good seal are hard to exactly emulate with a copy. Even on a two-dimensional surface. And with the advent of three-dimensional surfaces, which sealing wax made possible, the fine detail of a good seal was in fact very hard to forge.
Not impossible, but very costly with the technology of the day. Or even the technology of _today_. After all, paper currency is largely based on seal technology, with various embossing, printing, etc. methods used (on special paper) that remain fairly hard to duplicate.
The House Banking, Finance and Urban Affairs Committee last year held hearings on the redesign of the U.S. currency. Some of the testimony about physical document security was pretty interesting (for those with the requisite proclivities). I only have a hardcopy, though if enough people are interested, I might be persuaded to scan some of it in. -- Mark Chen chen@intuit.com 415/329-6913 finger for PGP public key D4 99 54 2A 98 B1 48 0C CF 95 A5 B0 6E E0 1E 1D