Cryptography Reference
In-Depth Information
Young and Yung's research was motivated by the U.S. government's
“Capstone” proposal to develop cryptographic algorithms for encryption,
signature, key exchange, and hashing and embed them in a hardware chip.
Given that the specifications of the encryption algorithm were classified,
“kleptography” provided additional arguments for the essential function
for peer review of cryptographic code by the scientific community: “Cap-
stone, cryptographic servers, and cryptographic libraries are all guards used
to prevent system infiltration . . . measures need to be taken to guard these
guards.” 53
Reconciling Authentication and Anonymity
Another strand of the problem of mutual cooperation in the absence of
trust was picked up by David Chaum, one of cryptography's most visible
figure in the 1980s and 1990s. Unlike Simmons, Chaum did not view
cryptography's role as merely replicating existing paper-and-pen protocols.
Rather, he envisioned it as an active intervention in severing the link
between increased computerization and data collection practices.
In several widely read publications, Chaum articulated a broad-reaching
research program seeking to provide the mathematical foundations for the
design of computer systems supportive of transactional anonymity—for
example, pseudonym systems and anonymous cash. 54 Whereas Simmons
had sought to unlink authentication from secrecy, Chaum sought to unlink
authentication from identification and developed a series of cryptographic
techniques whereby participants could perform information exchange pro-
tocols with surprising properties. Chaum called his central technique for
ensuring transactional anonymity “blind signatures,” which could be
applied to payment, voting, or credentials systems. A blind signature is a
verifiable digital signature on a document (say, a bank note), with the
property that the signatory has seen neither the document nor the result-
ing digital signature. A bank could, for example, issue such signed bank
notes and provide customers with the assurance that it could not trace its
subsequent use. 55 The implications of Chaum's work were important for
global networking, suggesting ways to make traffic analysis difficult for
several types of transactions.
Chaum's entrepreneurial ambitions led him to secure numerous patents
on his ideas. He founded DigiCash in 1990, a celebrated start-up that
sought to commercialize anonymous electronic cash but eventually filed
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