・2009年〜2015年 ダウンタイムゼロ ストレステストに耐え続け、現在に至る
・Counterparty on top of Bitcoin Blockchain = permissionless on permissionless
・sidechains = permissioned or premissionless on permissionless
・Hybrid of PoW and PoS?: Ethereum
MIT Technology Review
Chain ビットコイン → プライベート
Visa, Nasdaq, Citi, CapitalOne, fiserv., orangeから$30M出資
Chain was founded in early 2014 to provide software for the nascent Bitcoin industry. But the company
decided to switch to developing private blockchain technology after meeting with executives from Wall
Street companies who made it clear that Bitcoin was not suited to large-scale financial services, says
For one, Bitcoin was designed to primarily support transactions in Bitcoin over the Internet, but Ludwin
found that financial companies didn’t care much for the currency. They were interested in better ways
to move their existing assets around. Another problem was the volume and speed of transactions.
Bitcoin’s design currently supports only roughly seven transactions per second. On average, it
takes a new transaction 10 minutes to be added to the blockchain. And the total value of all
Bitcoins today, underpinned by its blockchain, is $3.4 billion, a small figure to large banks.
Barry Silvert ザ・ブロックチェーン
“We’re likely going to see years of exploration and talking and some preliminary
products with companies like Chain, but it’ll be a very narrow use case,” says
Silbert. He predicts that in coming years Bitcoin will rise to become a recognized
store of value of something like gold, and that innovation in its design and services
built on top will see the original, public blockchain become an underpinning for
financial services of all kinds. “Eventually Wall Street will come to appreciate
that the Bitcoin blockchain is the most secure and most flexible and can
solve a lot of the issues that they have,” he says.
Ludwin also thinks Bitcoin will survive, but he says it will only represent a fraction
of the value of less-radically open blockchains. Nakamoto’s invention will persist
as a kind of backstop that offers a way for people unable to use or trust more
conventional financial systems to move money around, he says. “The
encroachment of other asset classes is actually bad for that; we need Bitcoin to
thrive at that level,” he says. “The long-term vision is where we have many
blockchains that are interoperable, as opposed to a single chain where
everything is wedged in.”
“[Bank] bureaucracies are so heavily invested in the expertise and importance of local regulations and standards that it’s
extremely difficult for them to cut the Gordian knot and implement seamless global systems,” said Szabo. “So they keep
trying to re-inject points of control, and thus points of vulnerability, into blockchains, e.g. through ‘permissioning’; but this
nullifies their main benefits, which come from removing points of vulnerability.”
On the contrary, according to Szabo, the banks should embrace the crowd-sourced power and resiliency of
permissionless blockchains like Bitcoin.
If banks were to embrace permissionless blockchains they could participate as well or better than the newcomers, Szabo told IBTimes UK.
"But their bureaucracies are so heavily invested in the expertise and importance of local regulations and standards that it's extremely difficult for them to cut the Gordian knot and
implement seamless global systems.
"So they keep trying to re-inject points of control, and thus points of vulnerability, into blockchains, e.g. through 'permissioning'; but this nullifies their main benefits, which come from
removing points of vulnerability."
Szabo reiterated the point: to remove vulnerability banks also have to remove individual human control and the individuals in charge or with root access. Banks naturally hate that loss to
their power. But they don't have any choice if they want to gain the benefits of having an army of independent computers that rigorously, constantly and securely check each others' work,
Szabo pointed out that proper financial controls are already somewhat decentralised, thanks to a "human blockchain" of accountants, auditors, etc. checking each others' work.
"There are half a dozen or so different entities involved when you do a stock trade on Wall Street, again checking each others' work. You typically see full vulnerability to unaccountable
third parties only in pathological situations where naive newcomers try to do money on the centralised web, as with Mt.Gox.
"But the traditional 'human blockchain' is very labor-intensive and very local — each is based on local regulations and customs and thus splits the world up into mutually untrusting
national silos. Permissionless blockchains cut through that like Alexander cutting through the Gordian knot."
Nick Szabo: If banks want benefits of blockchains they must
"I'm surprised they honed in on that first. A private
federated blockchain doesn't solve any major problems
and ultimately I don't have a high level of optimism it's
going to succeed. I'm surprised they haven't figured that
out yet and I'm surprised they are doing that first."
・サイファーパンク 対 巨大投資銀行
・サイファーパンク（Nick Szabo, Adam Back, Greg Maxwell and etc.）はビットコインを