Wei Dai

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Wei Dai

Wei Dai (戴维 in Pinyin).[1] is a computer engineer[2] and cypherpunk[3] best known as creator of 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[4] and is described as an "intensely private computer engineer".[2] His profile as a member of the advisory board[5] for the (now defunct) VoteHere.net indicated:

"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."


Dai has made numerous contributions to the field of cryptography and has identified critical Cipher Block Chaining (CBC) vulnerabilities affecting SSH2[6] and the browser exploit against SSL/TLS known as BEAST (Browser Exploit Against SSL/TLS).[7][8]


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 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.[9]


In 1998, Dai helped to spark interest in cryptocurrencies[10] 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".[11]

Influence on the development of Bitcoin

Described as "money which is impossible to regulate",[12] Dai's b-money described the core concepts later implemented in Bitcoin[13] 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., 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[2] and the b-money paper was referenced in the subsequent Bitcoin whitepaper.[14]

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

Myself, Wei Dai, and 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).[15]

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

...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.[16]

There has been much speculation as to the identity of Satoshi Nakamoto, with suspects including Wei Dai, Nick Szabo, Hal Finney and accompanying denials.[17][18][10][19]

Wei currency unit

The smallest unit of Ether (cryptocurrency of the Ethereum network) is the wei (named after Wei Dai).[20][21]

External links


  1. Wei Dai (January 12, 2014). "Wei Dai Ask any LessWronger anything". http://lesswrong.com/lw/jgz/aalwa_ask_any_lesswronger_anything/ap3c.
  2. 2.0 2.1 2.2 Popper, Nathaniel (May 15, 2015). "Decoding the Enigma of Satoshi Nakamoto and the Birth of Bitcoin". New York Times. http://www.nytimes.com/2015/05/17/business/decoding-the-enigma-of-satoshi-nakamoto-and-the-birth-of-bitcoin.html. Retrieved 31 August 2015.
  3. Andrew Smith (March 2, 2014). "Desperately seeking Satoshi". The Sunday Times. http://failover-www.thesundaytimes.co.uk/Magazine/article1379779.html.
  4. Morgen E. Peck (May 30, 2012). "Bitcoin: The Cryptoanarchists’ Answer to Cash". IEEE Spectrum. http://spectrum.ieee.org/computing/software/bitcoin-the-cryptoanarchists-answer-to-cash.
  5. Kerry Alexander (April 19, 2000). "B-Money". 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.
  6. ZiJie, Xu. "Some Fixes To SSH". http://eprint.iacr.org/2013/151.pdf. Retrieved 16 September 2015.
  7. Goodin, Dan (Sep 21, 2011). "Google preps Chrome fix to slay SSL-attacking BEAST". The Register. http://www.theregister.co.uk/2011/09/21/google_chrome_patch_for_beast/. Retrieved 16 September 2015.
  8. Bard, Gregory V.. "A Challenging but Feasible Blockwise-Adaptive Chosen-Plaintext Attack on SSL". University of Maryland, Department of Mathematics. http://citeseerx.ist.psu.edu/viewdoc/download?doi= Retrieved 16 September 2015.
  9. Krovetz, Ted; Dai, Wei (2007). "VHASH Security". http://citeseerx.ist.psu.edu/viewdoc/summary?doi= Retrieved 16 September 2015.
  10. 10.0 10.1 Peterson, Andrea (January 3, 2014). "Hal Finney received the first Bitcoin transaction. Here’s how he describes it.". The Washington Post. https://www.washingtonpost.com/news/the-switch/wp/2014/01/03/hal-finney-received-the-first-bitcoin-transaction-heres-how-he-describes-it/. Retrieved 16 September 2015.
  11. Wei Dai (1998). "B-Money". http://www.weidai.com/bmoney.txt.
  12. Daniel Cooper (May 8, 2013). "The rise (and rise?) of Bitcoin". Engadget. http://www.engadget.com/2013/05/08/engadget-primed-bitcoin/.
  13. DuPont, Quinn (2014). "The politics of cryptography: Bitcoin and the ordering machines.". Journal of Peer Production (1.4).
  14. Satoshi Nakamoto. "Bitcoin: A Peer-to-Peer Electronic Cash System". https://bitcoin.org/bitcoin.pdf.
  15. Nick Szabo (2011-05-28). "Bitcoin, what took ye so long?". Unenumerated. http://unenumerated.blogspot.com/2011/05/bitcoin-what-took-ye-so-long.html. Retrieved 2014-03-12.
  16. Wei Dai. "Wei_Dai comments on Making money with Bitcoin?". http://lesswrong.com/lw/4cs/making_money_with_bitcoin/3lq1.
  17. "Satoshi Nakamoto is (probably) Nick Szabo". LikeInAMirror. WordPress. Archived from the original on 2014-04-13. https://likeinamirror.wordpress.com/2013/12/01/satoshi-nakamoto-is-probably-nick-szabo/#%21. Retrieved 5 December 2013.
  18. Weisenthal, Joe (19 May 2013). "Here's The Problem With The New Theory That A Japanese Math Professor Is The Inventor Of Bitcoin". Business Insider. Archived from the original on 2013-11-03. http://www.businessinsider.com/did-shinichi-mochizuki-invent-bitcoin-2013-5. Retrieved 19 May 2013.
  19. Vigna, Paul (Apr 16, 2014). "Bitcoin Creator ‘Satoshi Nakamoto’ Unmasked–Again?". Wall Street Journal. http://blogs.wsj.com/moneybeat/2014/04/16/bitcoin-creator-satoshi-nakamoto-unmasked-again/. Retrieved 16 September 2015.
  20. Buterin, Vitalik. "[English White Paper: A Next-Generation Smart Contract and Decentralized Application Platform"]. ethereum / wiki on GitHub (Self-published). https://github.com/ethereum/wiki/wiki/%5BEnglish%5D-White-Paper. Retrieved 11 April 2014.
  21. Wood, DR. Gavin. "Ethereum: A Secure Decentralised Generalised Transaction Ledger". http://gavwood.com/Paper.pdf. Retrieved 16 September 2015.