*21:17* [Pub][ePrint]
A low complexity bit-parallel Montgomery multiplier based on squaring for trinomials , by Yin Li and Yiyang Chen
In this paper, we present a new bit-parallel Montgomery multiplier for $GF(2^m)$ generated with irreducible trinomials. A newly proposed divide-and-conquer approach is applied to simplify the polynomial multiplication while the Montgomery squaring is induced to simplify the modular reduction. Meanwhile, this design effectively exploits the overlapped elements in squaring and reduction operation to reduce the space complexity. As a result, the proposed multiplier has about 25\\% reduced space complexity compared with previous multipliers, with a slight increase of time complexity. Among five binary fields recommended by NIST for the ECDSA (Elliptic Curve Digital Signature Algorithm), there exist two fields, i.e., $GF(2^{409})$, $GF(2^{233})$,defined by trinomials. For these two fields, we show that our proposal outperforms the previous best known results if the space and time complexities are both considered.

*21:17* [Pub][ePrint]
Faster Maliciously Secure Two-Party Computation Using the GPU, by Tore Kasper Frederiksen and Thomas P. Jakobsen and Jesper Buus Nielsen
We present a new protocol for maliciously secure two-partycomputation based on cut-and-choose of garbled circuits using the recent idea of ``forge-and-loose\'\' which eliminates around a factor 3 of garbled circuits that needs to be constructed and evaluated. Our protocol introduces a new way to realize the \"forge-and-loose\" approach which avoids an auxiliary secure two-party computation protocol, does not rely on any number theoretic assumptions and parallelizes well in a same instruction, multiple data (SIMD) framework.With this approach we prove our protocol universally composable-secure against a malicious adversary assuming access to oblivious transfer, commitment and coin-tossing functionalities in the random oracle model.

Finally, we construct, and benchmark, a SIMD implementation of this protocol using a GPU as a massive SIMD device. The findings compare favorably with all previous implementations of maliciously secure, two-party computation.

*18:17* [Pub][ePrint]
Cryptanalysis of the MORE symmetric key fully homomorphic encryption scheme, by Boaz Tsaban and Noam Lifshitz
The fully homomorphic symmetric encryption scheme \\emph{MORE} encrypts keys by conjugation with a random invertible matrix over an RSA modulus.

We provide a two known-ciphertexts cryptanalysis recovering a linear dependence among

the two encrypted keys.

*18:17* [Pub][ePrint]
Practical and Secure Query Processing for Large-scale Encrypted Cloud Storage Systems, by Fangquan Cheng and Qian Wang and Kui Ren and Zhiyong Peng
With the increasing popularity of cloud-based data services, data owners are highly motivated to store their huge amount of (potentially sensitive) personal data files on remote servers in encrypted form. Clients later can query over the encrypted database to retrieve files of interest while preventing database servers from learning private information about the contents of files and queries.In this paper, we investigate new and novel SSE designs which meet all practical properties, including one-round multi-keyword query, comprehensive and practical privacy protection, sublinear search time, and efficient dynamic data operation support. Moreover, our solutions can well support parallel search and run for very large-scale cloud databases. Compared to the existing SSE solutions,

our solution is highly compact, efficient and flexible. Its performance and security are carefully characterized by rigorous analysis. Experimental evaluations conducted over large representative real-word data sets demonstrate that compared with the state-of-the-art our solution indeed achieves desirable properties for large-scale encrypted database systems.

*18:17* [Pub][ePrint]
Certification and Efficient Proofs of Committed Topology Graphs, by Thomas Gross
Digital signature schemes are a foundational cryptographic building block in certification and the projection of trust. Based on a signature scheme on committed graphs, we propose a toolkit of certification and proof methods to sign committed topology graphsand to prove properties of their certificates in zero-knowledge.

This toolkit allows an issuer, such as an auditor, to sign the topology representation of an infrastructure. The prover, such as an infrastructure provider, can then convince a verifier of topology properties, such as partitions, connectivity or isolation, without disclosing the structure of the topology itself. By that, we can achieve the certification of the structure of critical systems, such as infrastructure clouds or outsourced systems, while still maintaining confidentiality. We offer zero-knowledge proofs of knowledge for a general specification language of security goals for virtualized infrastructures, such that high-level security goalscan be proven over the topology certificate. Our method builds upon the Camenisch-Lysyanskaya signature scheme, is based on honest-verifier proofs and the strong RSA assumption.