# Wei Dai

Wei Dai (Chinese: 戴维 or Chinese: 戴伟) 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.

## Education and career

Dai graduated from the University of Washington with a degree in computer science, just before creating b-money in 1998.
He is described as an "intensely private computer engineer". Wei Dai was a member of the Cypherpunks, Extropians, and SL4 mailing lists in the 1990s. On SL4 he exchanged with people such as Eliezer Yudkowsky, Robin Hanson, Nick Bostrom, Aubrey de Grey, Anders Sandberg, Eric Drexler, David Pearce, Hal Finney, and others in a nascent rationalist community.
Dai has contributed 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++

Crypto++ is an open-source C++ library that provides implementations of cryptographic algorithms. It was originally written by Dai and first released in 1995. In June 2015 Dai stepped away from the Crypto++ project to work on other projects, with the Crypto++ community continuing to maintain the project.

### b-money

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".

### 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.

## Influence on the development of Bitcoin

Described as "money which is impossible to regulate", Dai's b-money described the core concepts later implemented in Bitcoin 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 and the b-money paper was referenced in the subsequent Bitcoin whitepaper.
In a May 2011 article, noted cryptographer Nick Szabo stated:
   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.
There has been much speculation as to the identity of Satoshi Nakamoto, with suspects including Wei Dai himself, Nick Szabo, and Hal Finney, all of whom have denied the putative identification.