A computer-implemented method for submitting feedback for an entity to a blockchain is disclosed. The method, which is implemented at one of a plurality of participating nodes, includes: obtaining a first key, the first key being one of a fixed set of keys distributed to participating nodes that are eligible to submit feedback for the entity; generating first feedback (r.sub.j) of the entity for submission to the blockchain; encrypting the first feedback (r.sub.j) using at least the first key; and submitting the encrypted first feedback to a mixing service, the mixing service being configured to generate a mixed transaction based on the encrypted first feedback and at least one other encrypted feedback submission from one or more eligible participating nodes.

Systems and methods are disclosed herein for improved per-frequency counting systems that record interactions between individuals and a group of providers while maintaining differential privacy. A protocol may be defined that specifies frequency bins to categorize identifiers corresponding to individuals. A provider may generate a plurality of private sketches, each corresponding to a plurality of frequencies defined in the protocol. Frequency data is determined for each identifier. Identifiers are encoded into the private sketches corresponding to the identifiers’ associated frequency. The plurality of private sketches from each provider in the group of providers are combined to generate a deduplicated distribution across the group. In one implementation, the private sketches of each provider are sequentially merged until all sketches have been combined, from which the total distribution can be estimated.

Disclosed is a method for verifying an electronic vote in a voting system, wherein each voter is associated with a respective token generated by an authentication process in the voting system and wherein each token is configured for identifying the respective voter while maintaining an anonymity of the voter in the voting system. The method comprises steps being performed by a device operably connected to the voting system of; obtaining a token associated with a voter for which a vote is to be verified, providing the obtained token to an access manager in the voting system, obtaining a signature sequence generated by the access manager, wherein the signature sequence is generated based on the provided token, generating an audit request based on the obtained signature sequence and the obtained token, wherein the generated audit request comprises a binary sequence of actions to be performed on a ballot associated with the vote to be verified, providing the generated audit request to a processing server in the voting system, and obtaining a recounted tally based on the audit request from the processing server for comparison with a published tally on a bulletin board of the voting system. Corresponding computer program product, apparatus, device, access manager, processing server and voting system are also disclosed.

This disclosure describes systems and techniques for using controlling access to user information using ephemeral user identifiers. In one aspect, a method includes determining, for a given domain, engagement by a user with content provided by the given domain for display by an application at a client device of the user. A determination is made, based on the engagement by the user, to extend, for the given domain, a linkage between user identifiers for a user of the application. In response to determining to extend, for the given domain, the linkage between the user identifiers for the user of the application, one or more future domain-specific ephemeral user identifiers for the user and the given domain are obtained. An attestation record that includes a current domain-specific ephemeral user identifier and the one or more is generated and sent to the given domain.

This disclosure relates to protecting the confidential information of multiple entities using secure multi-party computation (MPC) and k-anonymity techniques. In some aspects, a method includes receiving, by a first MPC computing system from a client device, a content request including encrypted user group identifiers. Each encrypted user group identifier is encrypted using a first encryption key of a second MPC computing system. For each encrypted user group identifier, a request is transmitted to the second MPC computing system. The request includes the encrypted user group identifier. For each user group identifier that satisfies a k-anonymity, the first MPC computing system receives, from the second MPC computing system, a plaintext value of the user group identifier. The first MPC computing system transmits a selection parameter request to one or more platforms. The selection parameter request includes the plaintext value of the user group identifier.

Techniques are disclosed to provide enforceable pseudonymous reputation through chained endorsers. In various embodiments, a request associated with a chained endorsement operation is received via a communication interface. A client identity information is extracted from the request. Data comprising or associated with the client identity information is combined with a secret value. A one-way transform of the combined value is performed. A result of the one-way transform is returned to a client with which the chained endorsement operation is associated.

Described in detail herein is a method for encrypting or encoding time-stamped location data associated with a computing device. The method converts time and location information associated with the computing device into a vector format. The method generates a code vector based on the converted time and location vector. The method sorts entries in the code vector based at least in part on a predetermined ordering scheme. The method executes a random modification to each of the sorted entries. The method compares the code vector to at least one other code vector associated with another computing device. The method identifies other code vectors within a specified distance of the given code vector. The method concludes that the computing device and the at least one other computing device were in proximity to each other during a time period corresponding to the time information.

Systems and methods are disclosed which use a block chain (“blockchain”) to enable the establishment of file dates and the absence of tampering, even for documents held in secrecy and those stored in uncontrolled environments, but which does not require trusting a timestamping authority or document archival service. In an exemplary operation, an internet browser retrieves a website document, hashes at least a portion of the website document to produce a first hash value, retrieves blockchain registration data for the website document; compares the first hash value with a second hash value found in a blockchain; and responsive to the first and second hash values matching, displays a verification indication. Some embodiments may be used as parental controls for internet browsers.

Embodiments facilitate interoperability and secure determination of healthcare costs. An entity may receive a first Electronic Health Record (EHR) sub-block with patient medical coverage information and first treatments and may transmit a first Device Drug Information (DIR) sub-block comprising first treatment classes corresponding to each first treatment, first treatment class members corresponding to each first treatment class, and corresponding first treatment class member cost information. In response, the entity may receive a second EHR sub-block comprising second treatments each: associated with a corresponding first treatment, and selected from corresponding first treatment class members. Upon receipt of a transaction confirmation, the entity may augment a multi-dimensional blockchain with a multi-dimensional block formed by linking: a DIR block including second treatment information, an EHR block including information based on the second EHR sub-block and a transaction block. Payment assistance information determined from the second EHR block may be transmitted to a patient.

An example operation may include one or more of identifying a first blockchain transaction stored on a blockchain ledger based on a first identifier of a user that submitted the first blockchain transaction, retrieving a secret key shared between an auditor node and the user, decrypting, via the auditor node, ciphertexts included in the first blockchain transaction based on the secret key to recover a second user identifier of the user, and identifying, via the auditor node, a second blockchain transaction of the user stored on the blockchain ledger which includes the second user identifier.