International Business Machines Corporation

Jan Leonhard Camenisch

Dieter M Sommer

Thomas R Gross

Gregory Neven

Maria Dubovitskaya

Christopher Mark Kenyon

Tadeusz J Pietraszek

Abhi A Shelat

Roger Daniel Zimmermann

Chris P Vanden Berghe

Kai Samelin

Jonathan A Poritz

Greg Zaverucha

Thomas Scott Heydt-Benjamin

Luca Alessandro Comparini

Computer-implemented methods for privacy attribute based credentials include issuing a privacy-preserving attribute-based credential, which is signed with a private key and has a unique credential handle; updating an accumulator in a tamperproof log to incorporate the credential handle; and facilitating providing access to a service in response to a zero-knowledge proof that the accumulator contains the credential handle. The methods also include generating revocation conditions and initial revocation information; submitting the initial revocation information and the revocation conditions to the tamperproof log; revoking a credential by adding a credential handle of the credential to the initial revocation information; and submitting the updated revocation information to the tamperproof log. Further, the methods include writing to the tamperproof log an audit token that contains an encrypted credential handle, which is encrypted by an auditor's public key that is published on the tamperproof log.

Establishing trust in an attribute authentication system

A method is provided for communicating messages between sender and receiver computers, connectable via a network to a system of servers, based on authentication of receiver passwords, associated with respective receiver IDs, by the system. A method is also provided for receiving a message from a sender based on authentication of a receiver password, associated with a receiver ID, by a system of servers, in a network, wherein each server stores for the ID a ciphertext produced by encrypting the receiver password under a public key via a homomorphic threshold encryption scheme having a threshold, and a key-share of a secret key corresponding to that public key, and stores an encrypted message from the sender encrypted under the public key. Systems are provided including servers, for communicating messages between sender and receiver computers based on authentication of receiver passwords, associated with respective receiver IDs, by the system.

Communication of messages over networks

A method, apparatus, and a computer readable storage medium having computer readable instructions to carry out the steps of the method for anonymous access to a database. Each record of the database has different access control permissions (e.g. attributes, roles, or rights). The method allows users to access the database record while the database does not learn who queries a record. The database does not know which record is being queried: (i) the access control list of that record or (ii) whether a user's attempt to access a record had been successful. The user can only obtain a single record per query and only those records for which he has the correct permissions. The user does not learn any other information about the database structure and the access control lists other than whether he was granted access to the queried record, and if so, the content of the record.

Oblivious transfer with hidden access control lists

A method and system for performing transactions between a client and a server. The client sends to the server a transaction request for performing a transaction, and receives from the server a transaction policy. The client displays a first representation of the transaction policy depicting transaction policy options for fulfilling the transaction policy. After the user selects a first transaction policy option, the client displays a second representation of the transaction policy, depicting at least one mechanism pertaining to the first transaction policy option for satisfying the requirements of the first transaction policy option. After the user selects a first mechanism, the client depicts evidence options for each requirement of the first transaction policy option. After the user selects an evidence option for each requirement of the first transaction policy option, the client sends to the server transaction enablement information that includes evidence dictated by the selected evidence options.

Method and computer system for performing transactions between a client and a server

Methods and apparatus are provided for cryptographically encoding secret data in a data processing system. The secret data is encoded in accordance with a verifiable encryption process to produce a cryptographic construction (&#x3b8;) having a decryption constraint dependent on the occurrence of a predetermined event. An event-dependent decryption constraint is thereby built into the cryptography, so that there is an intrinsic restriction on the ability to decrypt the encoded secret data which is dependent on occurrence of the predetermined event. Decoding apparatus for such a cryptographic construction is also provided, as well as distributed trust data processing systems providing accountable privacy based on use of such cryptographic constructions.

Cryptographic encoding and decoding of secret data

A system for verifying an electronic document, including a first device comprising a first display, a first interface and a first displaying program for displaying the electronic document on the first display, a second device comprising a second display, a second interface and a second displaying program, a communication channel between the first interface and the second interface, wherein the first and the second device are operable to exchange the electronic document and wherein the system comprises a selection function, the selection function for selecting a part of the electronic document and generating position information of the selected part of the electronic document, and wherein the second displaying program is operable to lock the electronic document after the exchange with the first device and display the selected part of the electronic document on the second display.

System and method for verifying an electronic document

A method and apparatus for attesting the configuration of a computing platform to a verifier. A signature key (SK) is bound to the platform and bound to a defined configuration of the platform. A credential (C(SK), C(SK)) for the signature key (SK) is obtained from an evaluator. This credential (C(SK), C(SK)) certifies that the signature key (SK) is bound to an unspecified trusted platform configuration. The platform can then demonstrate to the verifier the ability to sign a challenge from the verifier using the signature key (SK), and demonstrate possession of the credential (C(SK), C(SK)) to the verifier, thereby attesting that the platform has a trusted configuration without disclosing the platform configuration to the verifier.

Attestation of computing platforms

The invention relates to a method for providing an assertion message () from a proving party () to a relying party (), the method comprising the steps of: &#x2014;creating an assertion (A) comprising one or more statements, &#x2014;creating an assertion proof (p A), &#x2014;creating a temporary private key and a corresponding temporary public key (K) from the assertion (A) and the assertion proof (p A), &#x2014;creating a key proof (PK) for the temporary public key (K), &#x2014;creating an assertion message signature (S) by means of the temporary private key, &#x2014;creating the assertion message () comprising the temporary public key (K), the assertion proof (PA), the key proof (PK), the assertion (A), a message body () and the assertion message signature (S) to the relying party ().

Assertion message signatures

A method for automatically linking an anonymous electronic trade order having an order quantity (q) to an identity of a trader by providing an identity marker (s) of the trader; embedding the identity marker (s) by splitting the anonymous trade order into a number (n) of trade orders each having a corresponding order quantity x (i) to generate a trade order set; and placing the generated trade order set in an electronic order book.

Method and system for linking an anonymous electronic trade order to an identity of a trader

A method and apparatus for proving and a method and apparatus for verifying that a secret value is a member of a predetermined set of values. The proving mechanism receives a set of signatures which has respective values in the predetermined set signed using a private key. The proving mechanism sends to the verifying mechanism a commitment on the secret value of the proving mechanism. The proving mechanism and verifying mechanism then communicate to implement a proof of knowledge protocol demonstrating knowledge by the proving mechanism of a signature on the secret value committed to in the commitment, thus proving that the secret value is a member of the predetermined set.

Set membership proofs in data processing systems

A computer implemented method for performing a privacy enhanced comparison of a plurality of data sets includes allocating a private encryption key to each of the data sets; performing an encryption operation for each of the data sets, the encryption operation comprising generating a commutatively encrypted data set of the respective data set, wherein the commutatively encrypted data sets are generated by successively applying a keyed commutative encryption function on the respective data set with the private encryption key of the respective data set itself and with the private encryption keys of the other data sets; and comparing the commutatively encrypted data sets.

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Thalwil, Switzerland

Jan Leonhard Camenisch