Vitalik, the problem with this idea is the centralised entity/authority.
The centralised entity would need to have some sort of way to verify that a
user is indeed a human - most entities that do this require information
from you that would compromise anonymity.

If you have no way to verify that someone is indeed a human, then one
person can have thousands of PSCs and do a sybil attack, or they can just
obtain a new PSC when the identity behind one of their PSCs is compromised
and seen to be behind criminal actions.

Pirateat40 for example, or many other people behind bitcoin scams, if they
have the ability to just obtain a new username or pseudonym or in this
case, PSC - then there's no way to ensure they won't scam people again -
and there's also no way to ensure that they suffer the consequences of such
scams (one ancap way to do justice is through exclusion, which does not
work if the person can hide behind multiple identities).

Let me know what you think though, I'd love to flesh out of these ideas a
bit more :)


On Fri, Jul 12, 2013 at 1:11 PM, Vitalik Buterin <vbuterin@???> wrote:

> It is theoretically (ie. cryptographically) possible to limit quantity
> without compromising anonymity. The centralized solution would be to create
> a specialized currency, call it person-coin (PSC), and have a central
> authority give everyone 1 PSC. People can then use decentralized mixers,
> Zerocoin, etc, to mix up their PSC, and then to use your unique identity
> you sign a message with the address owning the PSC. You can recover a
> public key from a signature, so any kind of online service would simply
> maintain a list of all public keys to check for duplicates.
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