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In 1968 Shirley Chisholm became the first Black woman elected to the United States Congress. In 1972 she launched a campaign for the Democratic presidential nomination, breaking another political barrier.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
David Chaum | |
|---|---|
 Chaum in 2018 | |
| Born | 1955 (age 70–71) |
| Education | University of California, Berkeley |
| Occupations | |
| Known for | |
| Scientific career | |
| Fields | Computer science |
| Thesis | Computer Systems Established, Maintained, and Trusted by Mutually Suspicious Groups (1982) |
| Bernard Marcel Mont-Reynaud | |
| Website | www |
David Lee Chaum (born 1955) is an American computer scientist, cryptographer, and inventor. He is known as a pioneer in cryptography and privacy-preserving technologies and widely recognized as the inventor of digital cash. His 1982 dissertation, "Computer Systems Established, Maintained, and Trusted by Mutually Suspicious Groups," is the first known proposal for a blockchain protocol.[1] Complete with the code to implement the protocol, Chaum's dissertation proposed all but one element of the blockchain later detailed in the Bitcoin whitepaper. He has been referred to as "the father of online anonymity",[2] and "the godfather of cryptocurrency."[3]
He is also known for developing ecash, an electronic cash application that aims to preserve a user's anonymity, and inventing many cryptographic protocols like the blind signature, mix networks, and the Dining Cryptographers Protocol. In 1995, his company DigiCash created the first digital currency with eCash.[4]: 65–70 His 1981 paper, "Untraceable Electronic Mail, Return Addresses, and Digital Pseudonyms," laid the groundwork for the field of anonymous communications research.[5]
More recently, in 2020, Chaum founded the xx network, a privacy-focused blockchain platform, and in 2021 launched xx coin (abbreviation XX), a cryptocurrency designed to enhance user privacy and provide quantum resistance.[6][7]
Chaum was born to a Jewish family in Los Angeles, California.[8] He gained a doctorate in computer science from the University of California, Berkeley, in 1982.[9][10] Also that year, he founded the International Association for Cryptologic Research (IACR), which currently organizes academic conferences in cryptography research.[11]: 47 Subsequently, he taught at the New York University Graduate School of Business Administration and at the University of California, Santa Barbara (UCSB). He also formed a cryptography research group at CWI, the Dutch National Research Institute for Mathematics and Computer Science in Amsterdam.[12] He founded DigiCash, an electronic cash company, in 1990.[4]: 119
Chaum received the Information Technology European Award for 1995.[13] In 2004, he was named an IACR Fellow.[14] In 2010, at the RSA Conference, he was honored with the RSA Award for Excellence in Mathematics.[15] In 2019, he was awarded the honorary title of Dijkstra Fellow by CWI.[16] He received an honorary doctorate from the University of Lugano in 2021.[17]
Chaum resides in Sherman Oaks, Los Angeles.[18]
Recently credited by Alan Sherman's "On the Origins and Variations of Blockchain Technologies",[1] Chaum's 1982 Berkeley dissertation proposed every element of the blockchain found in Bitcoin except proof of work. The proposed vault system lays out a plan for achieving consensus state between nodes, chaining the history of consensus in blocks, and immutably time-stamping the chained data. The paper also lays out the specific code to implement such a protocol.
Chaum is credited as the inventor of secure digital cash for his 1983 paper, which also introduced the cryptographic primitive of a blind signature.[19] These ideas have been described as the technical roots of the vision of the Cypherpunk movement that began in the late 1980s.[20] Chaum's proposal allowed users to obtain digital currency from a bank and spend it in a manner that is untraceable by the bank or any other party.[21] In 1988, he extended this idea (with Amos Fiat and Moni Naor) to allow offline transactions that enable detection of double-spending.[22]
In 1990, he founded DigiCash, an electronic cash company, in Amsterdam to commercialize the ideas in his research.[4]: 119 The first electronic payment was sent in 1994.[23] In 1998, DigiCash filed for bankruptcy, and in 1999 Chaum sold off DigiCash and ended his involvement with the company.[12][24]
In 2021, Chaum, Claude Crépeau, and Ivan Damgård received a 30-Year STOC Test of Time Award from the ACM Special Interest Group on Algorithms and Computation Theory (SIGACT) for their 1988 paper, "Multiparty Unconditionally Secure Protocols." The paper was recognized as one of three seminal works on information-theoretically secure multiparty computation. [1]
In the same 1982 paper that proposed digital cash, Chaum introduced blind signatures.[19] This form of digital signature blinds the content of a message before it is signed, so that the signer cannot determine the content. The resulting blind signature can be publicly verified against the original, unblinded message in the manner of a regular digital signature.[25]
In 1989, he (with Hans van Antwerpen) introduced undeniable signatures.[26] This form of digital signature uses a verification process that is interactive, so that the signatory can limit who can verify the signature. Since signers may refuse to participate in the verification process, signatures are considered valid unless a signer specifically uses a disavowal protocol to prove that a given signature was not authentic.[27]
In 1991, he (with Eugene van Heyst) introduced group signatures, which allow a member of a group to anonymously sign a message on behalf of the entire group.[28] However an appointed group manager holds the power to revoke the anonymity of any signer in the case of disputes.[29]
In 1981, Chaum proposed the idea of an anonymous communication network in a paper.[30] His proposal, called mix networks, allows a group of senders to submit an encryption of a message and its recipient to a server. Once the server has a batch of messages, it will reorder and obfuscate the messages so that only this server knows which message came from which sender. The batch is then forwarded to another server who does the same process. Eventually, the messages reach the final server where they are fully decrypted and delivered to the recipient. A mechanism to allow return messages is also proposed. Mix networks are the basis of some remailers and are the conceptual ancestor to modern anonymous web browsing tools like Tor (based on onion routing). Chaum has advocated that every router be made, effectively, a Tor node.[31]
In 1988, Chaum introduced a different type of anonymous communication system called a DC-Net, which is a solution to his proposed Dining Cryptographers Problem.[32] DC-Nets is the basis of the software tool Dissent.[33]
In 2017, Chaum published a description of a new variety of mix network.[34] A real-world implementation of this network, called cMix and running on the xx network, later became the data transmission layer for the instant messaging platform xx messenger.[35]
Chaum has made numerous contributions to secure voting systems, including the first proposal of a system that is end-to-end verifiable. This proposal, made in 1981,[30] was given as an application of mix networks. In this system, the individual ballots of voters were kept private which anyone could verify that the tally was counted correctly. This, and other early cryptographic voting systems, assumed that voters could reliably compute values with their personal computers. In 1991,[citation needed] Chaum introduced SureVote which allowed voters to cast a ballot from an untrustworthy voting system,[36] proposing a process now called "code voting" and used in remote voting systems like Remotegrity and DEMOS.[37][38]
In 1994, Chaum introduced the first in-person voting system in which voters cast ballots electronically at a polling station and cryptographically verify that the DRE did not modify their vote (or even learn what it was).[39] In the following years, Chaum proposed (often with others) a series a cryptographically verifiable voting systems that use conventional paper ballots: Prêt à Voter,[40] Punchscan,[41] and Scantegrity.[42] The city of Takoma Park, Maryland used Scantegrity for its November, 2009 election.[43] This was the first time a public sector election was run using any cryptographically verifiable voting system.[44]
In 2011, Chaum proposed Random Sample Elections.[45] This electoral system allows a verifiably random selection of voters, who can maintain their anonymity, to cast votes on behalf the entire electorate.[46]
In a 1979 report published as Memorandum No. UCB/ERL M79/10[47] by the Electronics Research Laboratory at the University of California, Berkeley, Chaum proposed a mechanism for splitting a cryptographic key into partial keys that could be distributed among mutually suspicious groups. This concept was a significant predecessor to what is now known as secret sharing.[48]
In 1985, Chaum proposed the original anonymous credential system,[21] which is sometimes also referred to as a pseudonym system.[49] This stems from the fact that the credentials of such a system are obtained from and shown to organizations using different pseudonyms that cannot be linked.
In 1988, Chaum with Gilles Brassard and Claude Crépeau published a paper [50] that introduced zero-knowledge arguments, as well as a security model using information-theoretic private channels, and also first formalized the concept of a commitment scheme.
1991, with Torben Pedersen, he demonstrated a well-cited zero-knowledge proof of a DDH tuple.[51] This proof is particularly useful as it can prove proper reencryption of an ElGamal ciphertext.
Chaum contributed to an important commitment scheme which is often attributed to Pedersen. In fact, Pedersen, in his 1991 paper,[52] cites a rump session talk on an unpublished paper by Jurjen Bos and Chaum for the scheme. It appeared even earlier in a paper by Chaum, Damgard, and Jeroen van de Graaf.[53]
In 1993 with Stefan Brands, Chaum introduced the concept of a distance-bounding protocol.[54]
In 2019, he was one of the speakers at the fifth Ethereum developer conference, which was held in Japan.[55]
In July 2024, Chaum was on a panel on the future of privacy at the Plasmacon conference at the United Nations University in Tokyo, Japan, with Vitalik Buterin, co-founder of Ethereum.[56]
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Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
David Lee Chaum (born 1955) is an American computer scientist, cryptographer, and inventor. He is known as a pioneer in cryptography and privacy-preserving technologies and widely recognized as the inventor of digital cash. His 1982 dissertation, "Computer Systems Established, Maintained, and Trusted by Mutually Suspicious Groups," is the first known proposal for a blockchain protocol. Complete with the code to implement the protocol, Chaum's dissertation proposed all but one element of the blockchain later detailed in the Bitcoin whitepaper. He has been referred to as "the father of online anonymity", and "the godfather of cryptocurrency." He is also known for developing ecash, an electronic cash application that aims to preserve a user's anonymity, and inventing many cryptographic protocols like the blind signature, mix networks, and the Dining Cryptographers Protocol. In 1995, his company DigiCash created the first digital currency with eCash. His 1981 paper, "Untraceable Electronic Mail, Return Addresses, and Digital Pseudonyms," laid the groundwork for the field of anonymous communications research. More recently, in 2020, Chaum founded the xx network, a privacy-focused blockchain platform, and in 2021 launched xx coin (abbreviation XX), a cryptocurrency designed to enhance user privacy and provide quantum resistance.
In cryptography a blind signature, as introduced by David Chaum, is a form of digital signature in which the content of a message is disguised (blinded) before it is signed. The resulting blind signature can be publicly verified against the original, unblinded message in the manner of a regular digital signature. Blind signatures are typically employed in privacy-related protocols where the signer and message author are different parties. Examples include cryptographic election systems and digital cash schemes. An often-used analogy to the cryptographic blind signature is the physical act of a voter enclosing a completed anonymous ballot in a special carbon paper lined envelope that has the voter's credentials pre-printed on the outside. An official verifies the credentials and signs the envelope, thereby transferring his signature to the ballot inside via the carbon paper. Once signed, the package is given back to the voter, who transfers the now signed ballot to a new unmarked normal envelope. Thus, the signer does not view the message content, but a third party can later verify the signature and know that the signature is valid within the limitations of the underlying signature scheme. Blind signatures can also be used to provide unlinkability, which prevents the signer from linking the blinded message it signs to a later un-blinded version that it may be called upon to verify. In this case, the signer's response is first "un-blinded" prior to verification in such a way that the signature remains valid for the un-blinded message. This can be useful in schemes where anonymity is required. Blind signature schemes can be implemented using a number of common public key signing schemes, for instance RSA and DSA. To perform such a signature, the message is first "blinded", typically by combining it in some way with a random "blinding factor". The blinded message is passed to a signer, who then signs it using a standard signing algorithm. The resulting message, along with the blinding factor, can be later verified against the signer's public key. In some blind signature schemes, such as RSA, it is even possible to remove the blinding factor from the signature before it is verified. In these schemes, the final output (message/signature) of the blind signature scheme is identical to that of the normal signing protocol.
Mix networks are routing protocols that create hard-to-trace communications by using a chain of proxy servers known as mixes which take in messages from multiple senders, shuffle them, and send them back out in random order to the next destination (possibly another mix node). This breaks the link between the source of the request and the destination, making it harder for eavesdroppers to trace end-to-end communications. Furthermore, mixes only know the node that it immediately received the message from, and the immediate destination to send the shuffled messages to, making the network resistant to malicious mix nodes. Each message is encrypted to each proxy using public key cryptography; the resulting encryption is layered like a Russian doll (except that each "doll" is of the same size) with the message as the innermost layer. Each proxy server strips off its own layer of encryption to reveal where to send the message next. If all but one of the proxy servers are compromised by the tracer, untraceability can still be achieved against some weaker adversaries. The concept of a mix "cryptosystem" in the context of electronic mail was first described by David Chaum in 1981 because of the "traffic analysis problem" (traffic analysis). Applications that are based on this concept include anonymous remailers (such as Mixmaster), onion routing, garlic routing, and key-based routing (including Tor, I2P, and Freenet). Large-scale implementations of the mix network concept began to emerge in the 2020s, driven by advancements in privacy-preserving technologies and decentralized infrastructure.
Mixmaster is a Type II anonymous remailer which sends messages in fixed-size packets and reorders them, preventing anyone watching the messages go in and out of remailers from tracing them. It is an implementation of a David Chaum's mix network.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Shirley Chisholm, elected in 1968.
