View source for Wei Dai

{{Infobox person
|name              = Wei Dai
|image             =
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|field             = [[cryptography]], [[computer science]], [[digital currencies]], [[crypto-anarchy]]
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|ethnicity         =
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|notable_students  =
|known_for         = [[#b-money|b-money]], [[Crypto++]], [[VMAC]]
|alma_mater        = Bachelor of Science degree from the [[University of Washington]] in computer science, with a minor in mathematics.
|influences        = [[Timothy C. May]], [[Cypherpunks]]
|influenced        = [[Satoshi Nakamoto]]
|awards            = 
|religion          =
|signature         =  <!--(filename only)-->
|footnotes         =
|website           = {{URL|http://www.weidai.com/}}
}}

'''Wei Dai''' (戴维 in Pinyin).<ref>{{cite web|title=Wei Dai Ask any LessWronger anything|url=http://lesswrong.com/lw/jgz/aalwa_ask_any_lesswronger_anything/ap3c|author=Wei Dai|date=January 12, 2014}}</ref> is a computer engineer<ref name=nytimes-satoshi>{{cite news|last1=Popper|first1=Nathaniel|title=Decoding the Enigma of Satoshi Nakamoto and the Birth of Bitcoin|url=http://www.nytimes.com/2015/05/17/business/decoding-the-enigma-of-satoshi-nakamoto-and-the-birth-of-bitcoin.html|accessdate=31 August 2015|work=New York Times|date=May 15, 2015}}</ref> and cypherpunk<ref>{{cite news|author=Andrew Smith|work=The Sunday Times|date=March 2, 2014|url=http://failover-www.thesundaytimes.co.uk/Magazine/article1379779.html|title=Desperately seeking Satoshi}}</ref> best known as creator of [[#b-money|b-money]] and the developer of the Crypto++ library.  Dai is listed as inventor on U.S. patents 5724279 and 6081598 which were assigned to Microsoft.

== Education and career ==
Mr. Dai graduated from the University of Washington with a degree in computer science<ref name="ieee-spectrum-2012">{{cite web|title=Bitcoin: The Cryptoanarchists’ Answer to Cash|url=http://spectrum.ieee.org/computing/software/bitcoin-the-cryptoanarchists-answer-to-cash|author=Morgen E. Peck|date=May 30, 2012|work=IEEE Spectrum}}</ref> and is described as an "intensely private computer engineer".<ref name=nytimes-satoshi></ref>  His profile as a member of the advisory board<ref>{{cite web|title=B-Money|url=http://www.zoominfo.com/CachedPage/?archive_id=0&page_id=305671154&page_url=//www.registerhere.net/news/archive00/041900.html&page_last_updated=2002-07-16T11:05:01&firstName=Wei&lastName=Dai|author=Kerry Alexander|date=April 19, 2000}}</ref> for the (now defunct) VoteHere.net indicated:
<blockquote>
"Mr. Dai worked in the Cryptography Research Group at Microsoft Corporation in Redmond, Washington. While at Microsoft, he was involved in the study, design and implementation of cryptosystems for specialized applications. Prior to joining Microsoft, Mr. Dai was a programmer with TerraSciences of Acton, Massachusetts. Mr. Dai holds a Bachelor of Science degree from the University of Washington in computer science, with a minor in mathematics."
</blockquote>

== Cryptography ==
Dai has made numerous contributions to the field of cryptography and has identified critical Cipher Block Chaining (CBC) vulnerabilities affecting SSH2<ref>{{cite web|last1=ZiJie|first1=Xu|title=Some Fixes To SSH|url=http://eprint.iacr.org/2013/151.pdf|website=International Association for Cryptologic Research|accessdate=16 September 2015}}</ref> and the browser exploit against SSL/TLS known as BEAST (Browser Exploit Against SSL/TLS).<ref>{{cite news|last1=Goodin|first1=Dan|title=Google preps Chrome fix to slay SSL-attacking BEAST|url=http://www.theregister.co.uk/2011/09/21/google_chrome_patch_for_beast/|accessdate=16 September 2015|work=The Register|date=Sep 21, 2011}}</ref><ref>{{cite web|last1=Bard|first1=Gregory V.|title=A Challenging but Feasible Blockwise-Adaptive Chosen-Plaintext Attack on SSL|url=http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.61.5887&rep=rep1&type=pdf|publisher=University of Maryland, Department of Mathematics|accessdate=16 September 2015}}</ref>

=== Crypto++ ===
Crypto++ (also known as '''CryptoPP''', '''libcrypto++''', and '''libcryptopp''') is a free and open source C++ class library of cryptographic algorithms and schemes written by Wei Dai. Crypto++ has been widely used in academia, student projects, open source and non-commercial projects, as well as businesses.

=== VMAC ===
[https://en.wikipedia.org/wiki/VMAC VMAC] is a block cipher-based message authentication code (MAC) algorithm using a universal hash proposed by Ted Krovetz and Wei Dai in April 2007. The algorithm was designed for high performance backed by a formal analysis.<ref>{{cite web|last1=Krovetz|first1=Ted|last2=Dai|first2=Wei|title=VHASH Security|url=http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.65.9987|website=SiteSeerX|accessdate=16 September 2015|year=2007}}</ref>

=== b-money ===
In 1998, Dai helped to spark interest in [[Cryptocurrency|cryptocurrencies]]<ref name=washington-post-first-bitcoin /> with the publication of "b-money, an anonymous, distributed electronic cash system".  In the paper, Dai outlines the basic properties of all modern day cryptocurrency systems: "...a scheme for a group of untraceable digital pseudonyms to pay each other with money and to enforce contracts amongst themselves without outside help".<ref>{{cite web|title=B-Money|url=http://www.weidai.com/bmoney.txt|author=Wei Dai|year=1998}}</ref>

== Influence on the development of Bitcoin ==
Described as "money which is impossible to regulate",<ref>{{cite news|title=The rise (and rise?) of Bitcoin|url=http://www.engadget.com/2013/05/08/engadget-primed-bitcoin/|author=Daniel Cooper|work=Engadget|date=May 8, 2013}}</ref> Dai's '''b-money''' described the core concepts later implemented in [[Bitcoin]]<ref>{{cite journal|work=Journal of Peer Production|issue=1.4|title=The politics of cryptography: Bitcoin and the ordering machines.|author=DuPont, Quinn|year=2014}}</ref> and other cryptocurrencies:

* Requires a specified amount of computational work (aka [[Proof of work]]).
* The work done is verified by the community who update a collective ledger book.
* The worker is awarded funds for their effort.
* Exchange of funds is accomplished by collective bookkeeping and authenticated with cryptographic hashes.
* Contracts are enforced through the broadcast and signing of transactions with digital signatures (i.e., [https://en.wikipedia.org/wiki/Public-key_cryptography public key cryptography]).

=== Relationship with Satoshi Nakamoto ===
Wei Dai and [[Adam Back]] were the first two people contacted by [[Satoshi Nakamoto]] as he was developing [[Bitcoin]] in 2008<ref name=nytimes-satoshi></ref> and the b-money paper was referenced in the subsequent Bitcoin whitepaper.<ref>{{cite web|url=https://bitcoin.org/bitcoin.pdf|title=Bitcoin: A Peer-to-Peer Electronic Cash System|author=[[Satoshi Nakamoto]]|}}</ref>

In a May 2011 article, noted cryptographer [[Nick Szabo]] states:

{{quote|text=Myself, Wei Dai, and [[Hal Finney (cypherpunk)|Hal Finney]] were the only people I know of who liked the idea (or in Dai's case his related idea) enough to pursue it to any significant extent until Nakamoto (assuming Nakamoto is not really Finney or Dai).<ref>{{cite news|author=Nick Szabo |url=http://unenumerated.blogspot.com/2011/05/bitcoin-what-took-ye-so-long.html | title=Bitcoin, what took ye so long?|date=2011-05-28 |accessdate=2014-03-12|work=Unenumerated}}</ref>}}

However Dai questions b-money's influence on Bitcoin:

{{quote|text=...my understanding is that the creator of Bitcoin, who goes by the name Satoshi Nakamoto, didn't even read my article before reinventing the idea himself. He learned about it afterward and credited me in his paper. So my connection with the project is quite limited.<ref>{{cite web|url=http://lesswrong.com/lw/4cs/making_money_with_bitcoin/3lq1|title=Wei_Dai comments on Making money with Bitcoin?|author=Wei Dai|}}</ref>}}

There has been much speculation as to the identity of Satoshi Nakamoto, with suspects including Wei Dai, [[Nick Szabo]], [[Hal Finney (cypherpunk)|Hal Finney]] and accompanying denials.<ref name="LikeInAMirror1">{{cite web|title=Satoshi Nakamoto is (probably) Nick Szabo|url=https://likeinamirror.wordpress.com/2013/12/01/satoshi-nakamoto-is-probably-nick-szabo/#%21|work=LikeInAMirror|publisher=WordPress|accessdate=5 December 2013| archiveurl = http://web.archive.org/web/20140413135108/https://likeinamirror.wordpress.com/2013/12/01/satoshi-nakamoto-is-probably-nick-szabo/ | archivedate = 2014-04-13| deadurl=no}}</ref><ref>{{cite news |last= Weisenthal |first= Joe |url= http://www.businessinsider.com/did-shinichi-mochizuki-invent-bitcoin-2013-5|title= Here's The Problem With The New Theory That A Japanese Math Professor Is The Inventor Of Bitcoin |publisher= Business Insider| date= 19 May 2013 |accessdate = 19 May 2013 | archiveurl = http://web.archive.org/web/20131103105304/http://www.businessinsider.com/did-shinichi-mochizuki-invent-bitcoin-2013-5 | archivedate = 2013-11-03| deadurl=no}}</ref><ref name="washington-post-first-bitcoin">{{cite news|last1=Peterson|first1=Andrea|title=Hal Finney received the first Bitcoin transaction. Here’s how he describes it.|url=https://www.washingtonpost.com/news/the-switch/wp/2014/01/03/hal-finney-received-the-first-bitcoin-transaction-heres-how-he-describes-it/|accessdate=16 September 2015|work=The Washington Post|date=January 3, 2014}}</ref><ref>{{cite news|last1=Vigna|first1=Paul|title=Bitcoin Creator ‘Satoshi Nakamoto’ Unmasked–Again?|url=http://blogs.wsj.com/moneybeat/2014/04/16/bitcoin-creator-satoshi-nakamoto-unmasked-again/|accessdate=16 September 2015|work=Wall Street Journal|date=Apr 16, 2014}}</ref>

=== Wei currency unit ===
The smallest unit of [[Ethereum#Ether|Ether]] (cryptocurrency of the [[Ethereum]] network) is the '''wei''' (named after Wei Dai).<ref>{{cite journal |last = Buterin|first = Vitalik|authorlink = Vitalik Buterin|url = https://github.com/ethereum/wiki/wiki/%5BEnglish%5D-White-Paper|title = [English] White Paper: A Next-Generation Smart Contract and Decentralized Application Platform|work = ethereum / wiki on GitHub|publisher = Self-published|accessdate = 11 April 2014}}</ref><ref>{{cite web|last1=Wood|first1=DR. Gavin|title=Ethereum: A Secure Decentralised Generalised Transaction Ledger|url=http://gavwood.com/Paper.pdf|accessdate=16 September 2015}}</ref>

== External links ==
* [http://www.weidai.com/ Home page]
* [http://sourceforge.net/u/weidai/profile/ Profile on SourceForge]
* [http://lesswrong.com/user/Wei_Dai/submitted/ Posts on LessWrong]
* [http://nakamotoinstitute.org/authors/wei-dai/ Profile at the Nakamoto Institute]
* [https://scholar.google.com/citations?user=YQSmJLUAAAAJ&hl=en Wei Dai - Google Scholar Citations]

== References ==