International Business Machines Corporation

Emc Corporation

Ran Canetti

Nikolaos Triandopoulos

Dimitrios Papadopoulos

Andrew Stephen Tomkins

Shanmugasundaram Ravikumar

Shai Halevi

Sridhar Rajagopalan

Michael Steiner

Amit Sahai

Moses Samson Charikar

Methods and apparatus are provided for authenticated hierarchical set operations. A third party server processes a query (possibly from a client) on data sets outsourced by a source of the data. The query comprises a hierarchical set operation between at least two of the data sets. Authenticated Set Operation techniques for flat set operations can be iteratively applied for hierarchical set operations. In addition, bilinear accumulators are extended to provide an extractable accumulation scheme comprising a primary bilinear accumulator and a secondary bilinear accumulator. The client receives (i) an encoding of an answer to the query, (ii) a verification comprising, for example, one or more of subset witnesses, completeness witnesses, and/or accumulation values, and (iii) at least one argument for at least one intersection operation, union operation and/or set difference operation.

Authenticated hierarchical set operations and applications

Methods and apparatus are provided for authenticated hierarchical set operations. A third party server processes a query q (possibly from a client) on outsourced data sets S, . . . , Son behalf of a source of the data. The query q comprises a hierarchical set operation. Authenticated Set Operation techniques for flat set operations can be iteratively applied for hierarchical set operations. In addition, bilinear accumulators are extended to provide an extractable accumulation scheme comprising a primary bilinear accumulator and a secondary bilinear accumulator. In addition, a query q is parsed as a tree and for each tree node, a Union/Intersection argument is provided that is related to one or more accumulation values associated with the corresponding tree node. The client receives an answer to the query and a verification proof comprising, for example, subset witnesses, completeness witnesses, and/or accumulation values, but not necessarily intermediate results associated with the internal tree nodes of the query q.

The invention includes a method for key creation and recovery based on solutions to puzzles solvable by humans and not computers. In some exemplary embodiments, the key is created and recovered based on the solution(s) in conjunction with the password entered by the user. The puzzle(s) is selected based on the password used by the user from a puzzle database containing multiple puzzles that is greater in number to the number of puzzles used in conjunction with a particular password.

Mitigating dictionary attacks on password-protected local storage

An anonymous credential system which requires a user who is asserting a credential to have knowledge of the master key of the user who was originally granted that credential. In order for a user to transfer the ability to assert any one of their credentials to another user, they must also transfer their master key to that same user. The master key, however, provides such unlimited rights to its holder that a user is strongly motivated not to share their master key with anyone else. In this manner, anonymous credentials become non-transferrable because a user cannot transfer a credential without transferring their entire electronic identity.

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Brookline, MA, United States of America

Ran Canetti