Wei Dai (Chinese: 戴维) is a computer engineer known for contributions to cryptography and cryptocurrencies. He developed the Crypto++ cryptographic library, created the b-money cryptocurrency system, and co-proposed the VMAC message authentication algorithm. The smallest subunit of Ether, the wei, is named after him.
Dai has made numerous contributions to the field of cryptography and has identified critical Cipher Block Chaining (CBC) vulnerabilities affecting SSH2 and the browser exploit against SSL/TLS known as BEAST (Browser Exploit Against SSL/TLS).
Crypto++ (also known as CryptoPP, libcrypto++, and libcryptopp) is a free and open source C++ class library of cryptographic algorithms and schemes originally written by Wei Dai. Crypto++ has been widely used in academia, student projects, open source and non-commercial projects, as well as businesses.
In June 2015 Dai stepped away from the Crypto++ project to work on other projects. Crypto++ is now maintained by the Crypto++ community.
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.
In 1998, Dai helped to spark interest in cryptocurrencies 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".
Wei Dai and Adam Back were the first two people contacted by Satoshi Nakamoto as he was developing Bitcoin in 2008 and the b-money paper was referenced in the subsequent Bitcoin whitepaper.
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).
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.
^Bard, Gregory V. "A Challenging but Feasible Blockwise-Adaptive Chosen-Plaintext Attack on SSL". University of Maryland, Department of Mathematics. CiteSeerX10.1.1.61.5887. Cite journal requires |journal= (help)