A method for re-keying an encrypted data file, the data file being stored chunkwise on a storage entity (SE), data file chunks being encrypted with a global secret, and the method being performed in a memory available to a computing device, includes partially updating a global secret for encryption data for a data chunk to be re-keyed such that an output of a non-interactive oblivious key exchange is used to identify the private key of the data chunk to be re-keyed with a new private key; and reencrypting the data chunk to be re-keyed with the updated global secret.

A method for performing spacetime-constrained oblivious transfer between a party A and a party B. The method includes imposing relativistic signaling constraints on a cryptographic task of one out-of-m oblivious transfer involving parties A and B. The method further includes using quantum systems for the one-out of-m oblivious transfer. The method guarantees unconditional security of the spacetime-constrained oblivious transfer, based on the imposed relativistic signaling constraints and based on using quantum systems for the one-out of-m oblivious transfer.

Systems, computer-readable media and methods for enabling secure computation on spreadsheet software. A secure spreadsheet is implemented as an add-in to an existing spreadsheet program, or as a new spreadsheet program/web application, to allow secure computations on private input data (and also optionally with private functions) without the parties learning anything about them, via the familiar spreadsheet interface and its formula language. Automatic conversion of previous spreadsheet data and formulas is provided whenever possible, or assisted via a helper. The secure computation can be executed between the computers of the involved parties, or outsourced to a third-partycloud computing system (FIG. 4): the secure cryptographic calculation module automatically optimizes for the best performing technique of secure computation (for example, homomorphic encryption, garbled circuits, oblivious transfers, secret sharing, oblivious random access machines and/or a combination of the previous crypto-primitives).

A private set intersection protocol in which a third party may determine intersections of a first set of a first party and a second set of a second party. The third party may not obtain any information regarding the first set or the second set other than the intersection result. The protocol may be communicatively efficient and computationally efficient to allow for secure private set intersection to be performed.

The invention is directed to a system that enables an authentication process that involves secure multi-party computation. The authentication process can be performed between a user device operated by a user and an access device. The user device and the access device may conduct the authentication process such that enrollment information and authentication information input by the user is not transmitted between the devices. Instead, the user device may determine and utilize obfuscated values associated with the authentication information. The user device may also determine an obfuscated authentication function that can be utilized to determine an authentication result without revealing enrollment information and authentication information associated with the user. The user can be authenticated based on the authentication result.

A server module evaluates a circuit based on concealed inputs provided by respective participant modules, to provide a concealed output. By virtue of this approach, no party to the transaction (including the sever module) discovers any other party's non-concealed inputs. In a first implementation, the server module evaluates a garbled Boolean circuit. This implementation also uses a three-way oblivious transfer technique to provide a concealed input from one of the participant modules to the serer module. In a second implementation, the server module evaluates an arithmetic circuit based on ciphertexts that have been produced using a fully homomorphic encryption technique. This implementation modifies multiplication operations that are performed in the evaluation of the arithmetic circuit by a modifier factor; this removes bounds placed on the number of the multiplication operations that can be performed.

Systems, methods and financial instruments enhanced with secure computation. A financial instrument management system is implemented with secure computation capabilities, respecting the privacy and secrecy rights during computation of the information contained within financial instruments, external datasets and/or secure computation programs. Automatic conversion and aggregation of conventional financial instruments is also disclosed. Furthermore, secure computation programs can be certified with mathematical proofs about very advantageous and valuable properties such as their correct termination, conformance to a specification, or any other pre-conditions, post-conditions and invariants on their inputs and outputs, encrypted or in plaintext form.

Methods, systems, and articles of manufacture are provided for oblivious order preserving encryption. A method may include: traversing, by a cloud service provider, an order preserving encryption (OPE) tree based on a result of an oblivious comparison performed by a data owner and a data client, the OPE tree having nodes that each correspond to a ciphertext of data associated with the data owner, the ciphertext of the data being stored at the cloud service provider, and a relative position of the nodes within the OPE tree corresponding to an order that is present in the data associated with the data owner; and determining, based on the traversing of the OPE tree, an OPE encoding for an input value from the data client, the OPE encoding for the input value indicative of a position of a node corresponding to the input value within the OPE tree.

A system for authenticating a user accessing a device includes an authentication server and a ticket granting server. The authentication server is configured to generate a part of an authentication ticket which is combinable with at least one other part generated by at least one other authentication server to produce a complete authentication ticket, and to generate a part of a user session key which is combinable with at least one other part generated by the at least one other authentication server to produce a combined user session key. The ticket granting server is configured to authenticate the user by collaboratively, with at least one other ticket granting server, decrypting user request information using the combined user session key and comparing content of the decrypted user request information with the complete authentication ticket.

Updatable private set intersection (PSI) protocols allow parties that each have an updatable private set to determine the intersection of their sets after an update without the need to compare each element of each set and without compromising privacy. In some protocols, a first party can determine an update to the intersection by determining an intersection of elements that were previously in the first party's set with elements that were added to the second party's set and determining an intersection of elements that were added to the first party's set with elements that are in the second party's (updated) set. In some protocols, both parties can determine the updated intersection.