1
David Chaum: Cryptographic identification, financial transaction, and credential device. Spensley Horn Jubas & Lubitz, July 16, 1985: US04529870 (451 worldwide citation)

The invention provides a cryptographic apparatus which may be "personalized" to its owner. The apparatus may be utilized by its owner to identify himself to an external computer system, to perform various financial transactions with an external system, and to provide various kinds of credentials to ...


2
David Chaum: Card-computer moderated systems. Nixon & Vanderhye, May 15, 1990: US04926480 (320 worldwide citation)

A user controlled card computer C and communicating tamper-resistant part T are disclosed that conduct secure transactions with an external system S. All communication between T and S is moderated by C, who is able to prevent T and S from leaking any message or pre-arranged signals to each other. Ad ...


3
David Chaum, Peter L Hendrick: Automatic real-time highway toll collection from moving vehicles. Amtech Corporation, Nixon & Vanderhye, January 16, 1996: US05485520 (252 worldwide citation)

One or more roadside collection stations (RCS) communicate over a short-range, high speed bidirectional microwave communication link with one or more in-vehicle units (IVU) associated with one or more respectively corresponding vehicles in one or more traffic lanes of a highway. At least two up-link ...


4
David Chaum, Niels T Ferguson, Berry Schoenmakers, Erik W Voskuil: Partitioned information storage systems with controlled retrieval. DigiCash Incorporated, Nixon & Vanderhye P C, September 21, 1999: US05956400 (118 worldwide citation)

An information storage system includes one or more information update terminals, a mapper, one or more partial-databases, and one or more query terminals, exchanging messages over a set of communication channels. An identifier-mapping mechanism provides (to an update terminal) a method for delegatin ...


5
David Chaum, Niels Ferguson, Jelte Van Der Hoek: Multi-purpose transaction card system. InfoSpace, August 13, 2002: US06434238 (117 worldwide citation)

Disclosed is a multi-purpose transaction card system comprising an issuer, one or more cards, one or more terminals, and optionally one or more acquires, communicating using a variety of cryptographic confidentiality and authentication methods. Cards authenticate messages using public key based cryp ...


6
David Chaum: Undeniable signature systems. Nixon & Vanderhye, August 7, 1990: US04947430 (113 worldwide citation)

Cryptographic methods and apparatus for forming, checking, blinding, and unblinding of undeniable signatures are disclosed. The validity of such signatures is based on public keys and they are formed by a signing party with access to a corresponding private key, much as with public key digital signa ...


7
David Chaum: One-show blind signature systems. Nixon & Vanderhye, April 3, 1990: US04914698 (106 worldwide citation)

Numbers standing for cash money can be spent only one time each, otherwise the account from which they were withdrawn would be revealed. More generally, a technique for issuing and showing blind digital signatures ensures that if they are shown responsive to different challanges, then certain inform ...


8
David Chaum: Optionally moderated transaction systems. Nixon & Vanderhye, January 4, 1994: US05276736 (101 worldwide citation)

A tamper-resistant part is disclosed that can conduct transactions with an external system through a moderating user-controlled computer or that can on other occasions be brought into direct connection with the external system. In the moderated configuration, the moderating computer is able to ensur ...


9
David Chaum: Returned-value blind signature systems. Nixon & Vanderhye, August 14, 1990: US04949380 (100 worldwide citation)

A payer party obtains from a signer party by a blind signature system a first public key digital signature having a first value in a withdrawal transaction; the payer reduces the value of the first signature obtained from the first value to a second value and provides this reduced-value form of the ...


10
David Chaum: Compact endorsement signature systems. Nixon & Vanderhye, July 18, 1995: US05434919 (97 worldwide citation)

Cryptographic methods and apparatus for issuing (101), endorsing (102), and verifying (103, 104) compact endorsement signatures are disclosed. Such signatures allow an endorser to provide a public-key verifiable signature on a chosen message more efficiently than if the endorser were to make a publi ...