Patents by Inventor David Chaum

David Chaum has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6718314
    Abstract: 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 cryptographic without themselves performing the extensive computations usually associated with such cryptography. Integrity of complex transaction sequences and plural card storage updates are maintained even under intentionally generated interruptions and/or modifications of data transmitted between card and terminal. Cards do not reveal any information to the terminal which is not directly necessary for the transaction or any information to which the terminal should not have access, though externally measurable aspects of its behavior. Transaction types supported include those suitable for off-line credit cards, in which the “open to buy” is maintained on the card.
    Type: Grant
    Filed: August 12, 2002
    Date of Patent: April 6, 2004
    Assignee: Infospace, Inc.
    Inventors: David Chaum, Niels Ferguson, Jelte Van Der Hoek
  • Publication number: 20030205070
    Abstract: An electronic lock that can be pre-programmed or trained in the field to recognize ordinary flat metal keys by sensing their shape and comparing to a database is disclosed. The lock can be contained in standard configurations for door locks, communicates with external systems, provides control logic for querying and amending its database of allowed keys and rules, provides controlled access to logs of selected data, allows convenient but protected access to replacement batteries, can have all its electronics in the rotatable plug, can communicate and obtain power from devices in the adjacent door jam, can recognize special series key-blanks, can receive coded information entered using an unknown key that makes it useable, can be operated without a key to gain access with a code, can resist manipulation of the latching mechanism, can unlatch with very low power requirements, and provides for integration of almost all mechanism in silicon.
    Type: Application
    Filed: September 24, 2001
    Publication date: November 6, 2003
    Inventor: David Chaum
  • Publication number: 20030158775
    Abstract: An election system provides, in one example, each voter with multiple physical “layers” that the voter is able to choose between. The voter takes part of the layers as a kind of receipt and the other layers are retained and/or destroyed the system. The actual vote is not readily revealed by the layers taken by the voter, thus protecting against improper influence. In the voting booth, when all the layers are combined, however, the voter is readily able to verify the vote. Moreover, posted images of the layers not taken by the voter can be used to compute the election results in a way that is verifiable by interested parties. The results cannot be changed without substantial probability of detection and privacy of votes can be maintained unless a number of parties are compromised or collude.
    Type: Application
    Filed: January 21, 2003
    Publication date: August 21, 2003
    Inventor: David Chaum
  • Publication number: 20030104859
    Abstract: Random number generation and systems for their use are disclosed in which parts of some contributing values are committed to or hidden or uncontrollable before they are revealed or combined. Plural parties generally contribute to the process of developing the random values and in some exemplary systems incorporating the random generator concepts other parties perform and verify the operation of the system. In some preferred embodiments, commitments or physical locking are believed to impede various cheating and collusion strategies. In other exemplary embodiments values that are committed to by a system remain hidden while a user influences other values that are ultimately combined with committed values to determine the results. In some further exemplary embodiments users of ordinary skill are able to control their contributions and in other examples users are believed to be unable to deliberately choose their contribution.
    Type: Application
    Filed: December 5, 2002
    Publication date: June 5, 2003
    Inventor: David Chaum
  • Publication number: 20030097344
    Abstract: 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 cryptographic without themselves performing the extensive computations usually associated with such cryptography. Integrity of complex transaction sequences and plural card storage updates are maintained even under intentionally generated interruptions and/or modifications of data transmitted between card and terminal. Cards do not reveal any information to the terminal which is not directly necessary for the transaction or any information to which the terminal should not have access, though externally measurable aspects of its behavior. Transaction types supported include those suitable for off-line credit cards, in which the “open to buy” is maintained on the card.
    Type: Application
    Filed: August 12, 2002
    Publication date: May 22, 2003
    Inventors: David Chaum, Niels Ferguson, Jelte Van Der Hoek
  • Patent number: 6434238
    Abstract: 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 cryptographic without themselves performing the extensive computations usually associated with such cryptography. Integrity of complex transaction sequences and plural card storage updates are maintained, even under intentionally generated interruptions and/or modifications of data transmitted between card and terminal. Cards do not reveal any information to the terminal which is not directly necessary for the transaction or any information to which the terminal should not have access, though externally measurable aspects of its behavior. Transaction types supported include those suitable for off-line credit cards, in which the “open to buy” is maintained on the card.
    Type: Grant
    Filed: August 11, 1997
    Date of Patent: August 13, 2002
    Assignee: InfoSpace, Inc.
    Inventors: David Chaum, Niels Ferguson, Jelte Van Der Hoek
  • Patent number: 6318137
    Abstract: An electronic lock that can be pre-programmed or trained in the field to recognize ordinary flat metal keys by sensing their shape and comparing to a database is disclosed. The lock can be contained in standard configurations for door locks, communicates with external systems, provides control logic for querying and amending its database of allowed keys and rules, provides controlled access to logs of selected data, allows convenient but protected access to replacement batteries, can have all its electronics in the rotatable plug, can communicate and obtain power from devices in the adjacent door jam, can recognize special series key-blanks, can receive coded information entered using an unknown key that makes it useable, can be operated without a key to gain access with a code, can resist manipulation of the latching mechanism can unlatch with very low power requirements, and provides for integration of almost all mechanism in silicon.
    Type: Grant
    Filed: April 6, 1999
    Date of Patent: November 20, 2001
    Inventor: David Chaum
  • Publication number: 20010034640
    Abstract: Election automation systems are disclosed that allow plural entities, for example trustees, to ensure various properties of an election, including correctness of the outcome, by initially using confidential information to form printed ballots and transferring the ballots to voters. Later when voters electronically cast ballots, such as over networks, they use the confidential information and optionally physical ballot structures to authenticate information provided them, including information indicating whether their votes were received by the trustees. Voters can also use the information in ballots to ensure the secrecy of their vote while it is transmitted to the trustees. The trustees can tabulate results while preventing colluding subsets of trustees from being able to improperly modify the outcome of the election or violate the privacy of individual voters.
    Type: Application
    Filed: January 29, 2001
    Publication date: October 25, 2001
    Inventor: David Chaum
  • Patent number: 6035380
    Abstract: A single chip processor for use in a smart card has a plurality of instruction memory areas and a processor. Different instructions sets are selectively executable in response to a signal defining a memory area from which instructions are supplied. Preferably instruction and data memory areas are addressable as pages, wherein a page address cannot be directly accessed by a subset of instructions. The processor may include a central processing unit and a cryptographic logic unit which operate at different times and share common instruction memory and sequencing logic. Instructions are supplied to said cryptographic logic unit at an integer multiple of the rate at which they are supplied to said central processing unit.
    Type: Grant
    Filed: February 19, 1998
    Date of Patent: March 7, 2000
    Inventors: Christopher D. Shelton, Martin S. Kelly, William E. Orme, Marius P. M. Schilder, Niels T. Ferguson, David Chaum, Wolfgang Mayerwieser, Reinhard Posch, Volker Schindler
  • Patent number: 5956400
    Abstract: 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 delegating control over retrieval of the data stored at the partial-databases to one or more mappers, typically operated by one or more trusted third parties. Update terminals supply information, that is stored in fragmented form by the partial-databases. Data-fragment identifiers and pseudonyms are introduced, preventing unauthorized de-fragmentation of information--thus providing compliance to privacy legislation--while at the same time allowing query terminals to retrieve (part of) the stored data or learn properties of the stored data. The mapper is necessarily involved in both operations, allowing data access policies to be enforced and potential abuse of stored information to be reduced.
    Type: Grant
    Filed: July 19, 1996
    Date of Patent: September 21, 1999
    Assignee: DigiCash Incorporated
    Inventors: David Chaum, Niels T. Ferguson, Berry Schoenmakers, Erik W. Voskuil
  • Patent number: 5878140
    Abstract: Cryptographic methods and apparatus for payment and related transaction systems are disclosed that allow some kinds of tracing under some conditions and make substantially infeasible other kinds of tracing under other conditions.
    Type: Grant
    Filed: October 6, 1997
    Date of Patent: March 2, 1999
    Assignee: DigiCash Incorporated
    Inventor: David Chaum
  • Patent number: 5781631
    Abstract: Cryptographic methods and apparatus for payment and related transaction systems are disclosed that allow some kinds of tracing under some conditions and make substantially infeasible other kinds of tracing under other conditions.
    Type: Grant
    Filed: August 12, 1997
    Date of Patent: July 14, 1998
    Assignee: DigiCash Incorporated
    Inventor: David Chaum
  • Patent number: 5712913
    Abstract: Cryptographic methods and apparatus for payment and related transaction systems are disclosed that allow some kinds of tracing under some conditions and make substantially infeasible other kinds of tracing under other conditions.
    Type: Grant
    Filed: February 8, 1994
    Date of Patent: January 27, 1998
    Assignee: DigiCash Incorporated
    Inventor: David Chaum
  • Patent number: 5493614
    Abstract: Cryptographic methods and apparatus for forming (102) and verifying (103) private signatures and proofs (203,204, 207, and 209) are disclosed. Such a signature convinces the intended recipient that it is a valid undeniable or designated-confirmer signature. And such a proof convinces the intended recipient, just as any cryptographic proof. Even though the signatures and proofs are convincing to the intended recipient, they are not convincing to others who may obtain them.Unlike previously known techniques for convincing without transferring the ability to convince others, those disclosed here do not require interaction--a signature or proof can simply be sent as a single message. Because the intended recipient can forge the signatures and proofs, they are not convincing to others; but since only the intended recipient can forge them, they are convincing to the intended recipient.
    Type: Grant
    Filed: May 3, 1994
    Date of Patent: February 20, 1996
    Inventor: David Chaum
  • Patent number: 5485520
    Abstract: 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 (IVU to RCS) communication sessions and at least one downlink (RCS to IVU) communication session are transacted in real time during the limited duration of an RCS communication footprint as the vehicle travels along its lane past a highway toll plaza. Especially efficient data formatting and processing is utilized so as to permit, during this brief interval, computation of the requisite toll amount and a fully verified and cryptographically secured (preferably anonymous) debiting of a smart card containing electronic money. Preferably an untraceable electronic check is communicated in a cryptographically sealed envelope with opener.
    Type: Grant
    Filed: October 7, 1993
    Date of Patent: January 16, 1996
    Assignee: Amtech Corporation
    Inventors: David Chaum, Peter L. Hendrick
  • Patent number: 5434919
    Abstract: 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 public key signature, since the endorser needs only to perform conventional cryptographic operations and has to store less data per signature than required by previously known endorsement schemes.A hierarchy of compression functions takes a plurality of one-time signatures into the value upon which the public key signature is formed. Each endorsement uses up one of the one-time signatures and provides a subset of inputs to the compression hierarchy sufficient to allow its evaluation. Preparation for subsequent endorsements is made by pre-evaluating one-time signatures and saving only some of the intermediate values of the compression hierarchy.
    Type: Grant
    Filed: January 11, 1994
    Date of Patent: July 18, 1995
    Inventor: David Chaum
  • Patent number: 5373558
    Abstract: Cryptographic methods and apparatus for signing (101), receiving (102), verifying (103), and confirming (104) designated-confirmer signatures are disclosed. Such a signature (11) convinces the receiver that the confirmer can convince others that the signer issued the signature. Thus, more protection is provided to the recipient of a signature than with prior art zero-knowledge or undeniable signature techniques, and more protection is provided to the signer than with prior art self-authenticating signatures.A designated confirmer signature is formed in a setting where the signer creates and issues a public key (201) and the confirmer also creates and issues a public key (202). Should the confirmer offer a confirmation (13), the verifier is convinced that the signature was issued by the signer. Such confirmation can itself be, for example, self-authenticating, unconvincing to other parties, or designated confirmer.
    Type: Grant
    Filed: May 25, 1993
    Date of Patent: December 13, 1994
    Inventor: David Chaum
  • Patent number: 5276736
    Abstract: 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 ensure that certain transactions with the external system are unlinkable to each other. In the unmoderated configuration the tamper-resistant part can also ensure the unlinkability of certain transactions. Also testing configurations are disclosed that allow improper functioning of the tamper-resistant part, such as that which could link transactions, to be detected by user-controlled equipment. Another testing configuration can detect improper functioning of an external system that could, for instance, obtain linking information from a tamper-resistant part.
    Type: Grant
    Filed: July 13, 1992
    Date of Patent: January 4, 1994
    Inventor: David Chaum
  • Patent number: 5131039
    Abstract: 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 ensure that certain transactions with the external system are unlinkable to each other. In the unmoderated configuration, the tamper-resistant part can also ensure the unlinkability of certain transactions. Also testing configurations are disclosed that allow improper functioning of the tamper-resistant part, such as that which could link transactions, to be detected by user-controlled equipment. Another testing configuration can detect improper functioning of an external system that could, for instance, obtain linking information from a tamper-resistant part.
    Type: Grant
    Filed: November 5, 1990
    Date of Patent: July 14, 1992
    Inventor: David Chaum
  • Patent number: 4991210
    Abstract: Blind signature systems secure against chosen message attack are disclosed. Multiple candidate original messages can be accommodated. Each of plural candidates in the final signature can be marked by the party issuing the signature in a way that is unmodifiable by the party receiving the signatures. The exponents on the candidates in the final signature need not be predictable by either party. In some embodiments, these exponents are not at all or are only partly determined by the candidates in the signature shown. Single candidate signatures are also accommodated.
    Type: Grant
    Filed: May 4, 1989
    Date of Patent: February 5, 1991
    Inventor: David Chaum