(回答先: 英国王室領にあたるガーンジーの管轄下にあるノルマンディー諸島オルデニーでは、ビットコインを鋳造することを決定した。 投稿者 てんさい（い） 日時 2013 年 12 月 02 日 21:43:17)

2013年12月6日
http://jp.techcrunch.com/2013/12/06/20131205who-is-the-real-satoshi-nakamoto-one-researcher-may-have-found-the-answer/

先週インターネットでちょっと不思議なことが起きた。Skye Greyという研究者がBitcoinの創作者、Satoshi Nakamotoと、ジョージワシントン大学のNick Szaboという研究者が同一人物であるとする、詳細なテキスト分析結果を公開したところ、関心はおよそ薄かった。
https://likeinamirror.wordpress.com/2013/12/01/satoshi-nakamoto-is-probably-nick-szabo/

Greyは、個人的な内容に立ち入ることを拒んだが、果たして彼は謎を解明したのか？あるいは、例のごとく単なる臆測なのか。

果たしてSatoshが実在の人物なのか、集団なのか、あるいは何らかの政府組織でなのかは重要だ。それによって、この貸幣の誕生秘話は終りを告げ、Bitcoin市場の異端な部分に関する数多くの噂やほのめかしの真偽が確認される。果たしてBTCは、われわれが政府から逃がれるための方法だったのか、なぜSatoshiはそこまで秘密主義なのか？ Greyの分析は未だに証明も反証もされていないが、そのプロセスは実に興味をそそられる。

見たところGreyの分析は信頼できそうだったので、私は短かいインタビューを行うことにした。

TC：自身について。なぜこの研究を行ったのか？
SG：当初は単なる興味からだった。私はミステリー好きだ。その後2つの理由から公開する決心をした。
・他の人々に私の方法と発見を反証あるいは証明してもらうため。私は確信を持ちたかったし、自分の発見の真偽がわからないままになるのはいやだった。
・「悪いやつ」がBitcoinを作ったのではないか、という人々の懸念を解消したかった。この問題は、近い将来Bitcoinが主流になることを妨げると私は考えている。

TC：その人物がNick Szaboであるという確信はあるか？
SG：Nick Szaboであるという確信はないが、彼を指し示す個別の証拠が数多くあり、いずれも興味深い。
・テキスト分析（暗号研究者のわずか0.1%しか、この文章スタイルで書いていない ― 改めてお願いするが、これに関して私の方法を批判してほしい）
・Nickが、Bitcoin発表の数ヵ月前にbit goldプロジェクト（非常によく似た暗号化通貨）の共同研究者を探していたという事実（そして、それ以来bit goldプロジェクトが全く音沙汰なしであること）
・Nickの研究についてSatoshiが言及しておらず、より関連の薄い暗号化通貨には言及していること。
・NickがBitcoinについて発言していないこと。Bitcoinのような分散的通貨は10年以上にわたって彼の主要研究であったにもかかわらず。
・Nickが、Bitcoinの発表直後に、自分のbit goldに関する記事の日付を書き換えてBitcoinより後に見えるようにした事実。

現在私は、それぞれ独自のテキスト分析手法を持つ2人の人物に、私の方法を検証してもらおうとしている。

TC：これに意味はあるのか？ もしあるなら何が変わると思うか？
SG：Bitcoinの歴史上のこの時点でSatoshiの正体を特定することは非常に重要だと思っている。Bitcoinの背後に「筋書き」があるとして、もし代貸通貨の主流になるのであれば、陰のままでい続けることはできない。Bitcoinは政府機関（暗号を研究する数学者の主要雇用主）が、金銭取引のデータパターンを発見しやすくするために作った、という臆測もある。われわれの生活にBitcoinが深く浸透する前に、それを確かめておく必要がある。

もしNick Szaboが首謀者なら、Bitcoinにとってすばらしいニュースだと思う。Nickは、才気あふれる私欲のない博識な学者だと思われる。Bitcoinの創造者としてどちらがいいと思うだろうか？ 洞察力のある教授と協力者たち、それとも幽霊。

TC：BTCコミュニティーの反応は？ 不評な話題のようだが。
SG：まだ好意的に受け入れられておらず、人々は私に「Satoshiをそっとしておけ」と言っている。しかし、世界に大きな影響力を持つようになった人物は、匿名でいる権利を失う。Satoshiは現在約100万BTC、10億ドル相当を所有し、Bitcoin市場を破壊する潜在能力を持っている。われわれは、誰が自分たちを支配する権力を持っているか、その意図は何かを知る必要がある。リーダーを選ぶ際に素性調査が必要なのはこのためだ。同じように、われわれが貨幣交換取引に使い始める前に、Bitcoinシステムの「素性調査」が必要だ。その次は、Satoshiの隠しBTCがどうなるかを知ることだ。

おそらくSatoshiの匿名性は、Bitcoinの早期導入に役立っただろう（「誰もがSatoshi」）。その神秘性が早期熱狂者たちを引き込む強力なストーリーを生んだからだ。今この匿名性は、本流への参入を妨げている。Bitcoinの起源と目的に関する当然の懸念があるからだ。

TC：文章中の「癖」から個人を特定するのは簡単なのか？
SG：比較的簡単だ。人はみな独自の方法で言語を使っている。われわれの書く文章の中の、稀な表現、文構成、無意味な単語の確率分布は、一種の「シグナチャー」になる。指紋やDNAほどの特定識別性はないが、数百人数千人の中から1人を特定するのに十分な識別性はある。作家や学者等の中にはとりわけ特徴的な癖を持つ傾向の人がいて、確実な識別が可能だ。

Satoshiの場合、内容に依存しない稀な表現が、Satoshiの白書とNicksの論文から複数見つかった。そのうち4つの表現について、（Google Scholarを使って）論文でこれらの表現を使う可能性のある研究者が暗号学界にいる確率を推定することができた。確率はそれぞれ15%、10%、15%、および50%だった。それぞれの表現を使うする可能性が互いに独立であると仮定すると、ある研究者がその全部を著作物に使用する同時確率は0.1%のオーダーになる。つまり、この「癖」の組み合わせを用いて、1000人から1人の暗号研究者を識別できる。推定確率が大きくずれたとしても、同時確率はかなり小さいままだ。

TC：Satoshiのアイデンティティーに、僅差の次点はいるのか？
SG：Nickは、断トツでナンバーワンの候補だ。言うに値する名前は他にない。

TC：あなたはBitcoinをどれだけ持っているのか？
SG：1から10 BTCというところ。私はBitcoinに巨額な投資をしていないが、これが受け入れられる見通しについては、間違いなく楽観的だ。

（翻訳：Nob Takahashi / facebook）

https://likeinamirror.wordpress.com/2013/12/01/satoshi-nakamoto-is-probably-nick-szabo/

LikeInAMirror

Thoughts on computing

01Dec / 2013
Satoshi Nakamoto is (probably) Nick Szabo

I recently became interested in identifying the pseudonymous creator of Bitcoin, Satoshi Nakamoto. I started from the Bitcoin whitepaper [0] published in late 2008, and proceeded to run reverse textual analysis –essentially, searching the internet for highly unusual turns of phrase and vocabulary patterns (in particular places which you would expect a cryptography researcher to contribute to), then evaluating the fitness of each match found by running textual similarity metrics on several pages of their writing.

Which led me rather directly to several articles from Nick Szabo’s blog.

For those who wouldn’t know Nick Szabo and his documented links to Bitcoin: prior to the apparition of Bitcoin, Nick had been developing for several years (since 1998 [1]) the enabling mechanism for a decentralized digital currency, eventually converging on a system he called “bit gold” [3], which is the direct precursor to the Bitcoin architecture.

According to what seems to be a widely accepted origin story of Bitcoin, Satoshi Nakamoto was a highly skilled computer scientist (or group thereof) who found about Nick’s proposition for bit gold, hit upon an idea for bettering it, published the Bitcoin whitepaper, and decided to turn it into reality by developing the original Bitcoin client. Nick denies being Satoshi, and has stated his official opinion on Satoshi and Bitcoin in a May 2011 article [1].

I would argue that Satoshi is actually Nick Szabo himself, probably together with one or more technical collaborators.

As I mention above, what originally led me to this hypothesis is that reverse-searching for content similar to the Bitcoin whitepaper led me to Nick’s blog, completely independently of any knowledge of the official Bitcoin story. I must stress this: an open, unbiased search of texts similar in writing to the Bitcoin whitepaper over the entire Internet, identifies Nick’s bit gold articles as the best candidates. It could still be a coincidence, although an unlikely one -since cryptocurrencies were a fairly niche topic in 2008 and earlier (seemingly 3 or 4 people), every contributor to the field was going to be reusing the same shared expressions and vocabulary. Satoshi would have been a reader of Nick’s blog, so you would expect him to describe the same concepts in a similar way. But there’s more.

Running similarity metrics on the whitepaper and Nick’s bit gold articles as well as his paper “formalizing and securing relationships on public networks” [2] indicated an excellent match over content-neutral expressions as well –so either Nick wrote the whitepaper, or it was written by somebody imitating Nick’s writing style. Here is a brief summary of some of the more salient common points. For each expression, when it is possible and relevant, we will mention the proportion of cryptography papers containing the expression (using Google Scholar), to measure how common its use is among researchers, and later provide a rough value for the probability of the null hypothesis. Of course, we’ll only do this for content-neutral expressions.

Content-neural terms:

Repeated use of “of course” without isolating commas, contrary to convention (“the problem of course is”)
Expression “can be characterized”, frequent in Nick’s blog (found in 1% of crypto papers)
Use of “for our purposes” when describing hypotheses (found in 1.5% of crypto papers)
Starting sentences with “It should be noted”(found in 5.25% of crypto papers)
Use of “preclude” (found in 1.5% of crypto papers)
Expression “a level of “ + noun (“achieves a level of privacy by…”) as a standalone qualifier

Content-bearing terms that have common synonyms in the field and thus could easily have been expressed in a different way:

Expression “timestamp server”, central in the Bitcoin paper, used in Nick’s blog as early as January 2006
Repeated use of expression “trusted third party”
Expressions “cryptographic proof” and “digital signatures”
Repeated use of “timestamp” as a verb

Consider this: if we assume that, when a content-neutral expression is part of a researcher’s vocabulary, they use it in at least one in ten papers (for instance “for our purposes” appears in 1.5% of papers, so we’ll assume that 15% of researchers would be susceptible of using it in a paper), then the probability of finding all of “it should be noted”, “for our purposes”, “can be characterized” and “preclude” as part of a given researcher’s vocabulary has the upper bound 0.08%. That’s our p-value right there (8e-4): this particular combination could pinpoint one researcher in a thousand.

Of course, the “one in ten papers” hypothesis is purely arbitrary, so it’s up to you to judge if it is acceptable. It seems rather generous to me, as most researchers actually tend to constantly reuse the same handful of expressions.

In short: most of the unusual wording found in the Bitcoin whitepaper can also be found in recurring occurrences in Nick’s articles. Not all of it, though: the Britishism “favour” used by Satoshi is not used by Nick, who writes “favor”. However, the Bitcoin paper may have had several authors, Nick being merely the main one. In fact, since all the paper is written in American English except for this one word, it is highly probable that either the paper had several authors, or this one word was a deliberate attempt at adding confusion as to the origins of the paper.

Then, there is secondary evidence. It is obvious that Satoshi did extensive research about prior mentions of concepts similar to Bitcoin, as any proper scientist writing a paper would have. This is evidenced by Satoshi’s reference to Wei Dai’s b-money, as well as hashcash, while both of them do not even seem to have been a direct inspiration to Bitcoin. However, he made no mention of Nick Szabo’s bit gold, whereas Bitcoin is quite visibly built directly on top of the bit gold ideas. If Satoshi had been writing independently from Nick, wouldn’t he have cited his work as per proper scientific etiquette?

There is also the remarkable lack of public reaction on Nick’s part when Bitcoin started taking off. For somebody as deeply involved in these concepts as Nick, it strikes me as surprising that it took Nick many months to even mention Bitcoin, while his ideas were coming to life in an exciting way.

Another interesting fact that may or may not be significant, is that the main mentions of bit gold on Nick’s blog have been retroactively post-dated to appear as slightly posterior to the Bitcoin whitepaper, and this right after the publication of the whitepaper. There are two major articles on bit gold on Nick’s blog, one originally posted in December 2005 and post-dated to December 2008 [3], and one from April 2008, also post-dated to December 2008 [4] (note: it is possible to manually edit the dates of blog posts on Blogger, however the original date is still visible in the (uneditable) url of the posts).

It is unclear why this post-dating occurred –it cannot really be an effort to confuse the dating of the bit gold system, since it is widely documented to have been publicized prior to 2008 (and again, Nick asserted once that he had started working on the idea as early as 1998 [1]). I would guess that, shortly after the publication of the Bitcoin whitepaper, Nick found something to edit in both of his bit gold articles.

Lastly, one thing to consider is that the profiles of Nick and Satoshi match perfectly. Satoshi is highly likely to have an academic background (Nick is a professor with a significant publication history), as demonstrated by his mastery of scientific writing –writing a paper following proper scientific convention is something difficult to improvise if you haven’t already done it a few times. In fact, the whole idea of getting an idea out there by writing a scientific paper, of all things, is very academically-minded. And the idea of a decentralized digital currency was a central project of Nick’s, that only a handful of people were interested in around the time of publication of the whitepaper. Who was on the 2008 list of academics passionate about cryptocurrencies and who wrote like Nick Szabo? Nick Szabo.

In summary, it seems to me highly likely that Satoshi is Nick (and collaborators). At the very least, there is strong textual analysis evidence that Nick has written significant parts of the Bitcoin whitepaper. I would suppose that either Nick, wanting to get his long-time dream of a decentralized currency further, had contacted one or more technical collaborators that helped him address the shortcomings of bit gold and ship the first client under the collective name Satoshi Nakamoto, or that a brilliant engineer happened to hit upon a better solution for bit gold, contacted Nick, and they decided to bring it to life together. As a side-note, it seems much more likely that a Satoshi-like character inventing Bitcoin would first contact the original father of the project, rather than start devoting all of their resources to shipping what was largely somebody else’s pet idea.

The scenario in which Szabo goes to a technically-minded computer scientist to get help turning bit gold into a reality is strongly backed by the fact that in April 2008, just a few months before the announcement of Bitcoin, Nick was actively looking for collaborators on the bit gold project. He asks on his blog [5] :

“[bit gold] would greatly benefit from a demonstration, an experimental market (with e.g. a trusted third party substituted for the complex security that would be needed for a real system). Anybody want to help me code one up?”

So, after 10 years of thinking about bit gold, Nick becomes interested in producing a concrete implementation of his decentralized currency dream. What happens right after? The Bitcoin whitepaper and software.

Then again, keep in mind that these two scenarios are pure speculation on my part –the only thing that I do have serious evidence for is merely the authorship of the Bitcoin whitepaper.

[0] http://bitcoin.org/bitcoin.pdf

[1] http://unenumerated.blogspot.com/2011/05/bitcoin-what-took-ye-so-long.html

[2] http://firstmonday.org/ojs/index.php/fm/article/view/548/469

[3] http://unenumerated.blogspot.com/2005/12/bit-gold.html

[4] http://unenumerated.blogspot.com/2008/04/bit-gold-markets.html

[5] http://unenumerated.blogspot.com/2008/04/bit-gold-markets.html#3741843833998921269 　

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