Quote from: ifinta on December 28, 2011, 06:23:14 AM

http://en.wikipedia.org/wiki/Personally_identifiable_information
a fingerprint of a person, a computer, a cpu id or special HW

Can be cheated or played, special HW requires central authority.

I am identified in mtgox through a yubikey (+ some personal data - see wikipedia link)

Requires a central authority to manufacturing yubikeys

I am identified in Bitcoin forum through my activity (+ some personal data - e-mail, ...)

can be played, and requires a central authority
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bitcoin is designed to be DECENTRALIZED, it is a feature!
Therefor it does not need a single point of weekness. your plan is to introduce a SPOW into the bitcoin system, which is BAD. if we did that there would be no need for a blockchain at all, as the central authority could just validate every transaction, like creditcard companies does right now.