Perry says:

root says:

...

This is the same problem that arose with the original idea of seals once the skills of metalworking became commen enough. By the 1500's it was nearly impossible to keep a seal confidential more than a few weeks until somebody got a impression and built a copy.

Seals were duplicatable from the start. You just needed clay and a seal made with the oritinal if you wanted to forge them -- fairly common stuff. Signatures have been duplicatable from the start, too.

"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. (Not impossible, and counterfeiting flourishes. It's all about economics, and I'm only disputing the claims of easiness. As an added note, transactions in the Far East are still often "sealed" with "chop marks," carved stamps that are uniquely associated with persons or groups.)

Signatures and seals are NOT truly authenticating technologies. They are just a legal mechanism for an entity to demonstrate that it has read and agreed to the terms on a document. It was always assumed that someone might forge a signature, which is why if you had a document where you cared that people might disclaim their signature, you got people who could testify to the signature to witness the signing.

I think this understates the importance of signatures and seals in these earlier times. --Tim May .......................................................................... Timothy C. May | Crypto Anarchy: encryption, digital money, tcmay@netcom.com | anonymous networks, digital pseudonyms, zero 408-688-5409 | knowledge, reputations, information markets, W.A.S.T.E.: Aptos, CA | black markets, collapse of governments. Higher Power: 2^859433 | Public Key: PGP and MailSafe available. "National borders are just speed bumps on the information superhighway."