International Association for Cryptologic Research

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2014-12-19
18:00 [News] Call for IACR Cryptology School Proposals

 

In 2014, IACR started to sponsor a small number of Cryptology Schools providing intensive training on clearly identified topics in cryptology. The aim of this program is to develop awareness and increased capacity for research in cryptology.

A Cryptology School is typically held full-time for 4-5 days of intensive learning and constitutes an efficient way to provide high-quality training for graduate students, as well as for professionals. Attendance should be open to anyone who is interested and qualified. In order to facilitate learning, a school is usually taught by a few domain experts with a focus on educating the audience rather than impressing with results. In line with the mission of IACR, a Cryptology School should enable the audience to advance the theory and practice of cryptology and related fields.

There are two rounds of submissions every year. The submission deadlines are:

  • December 31st of year X-1: For schools that take place between March of year X and February of year X + 1.
  • June 30th of year X: For schools that take place between September of year X and August of year X + 1.
Submissions must be sent by email to schools@iacr.org.

For more information about this new program and how to prepare a proposal, please refer to http://www.iacr.org/schools/



15:09 [Event][New] RCD 2015: 3rd Romanian Cryptology Days Conference

  Submission: 15 May 2015
Notification: 15 June 2015
From September 21 to September 23
Location: Bucharest, Romania
More Information: http://www.sie.ro/rcd2015/




2014-12-18
05:08 [Pub][ePrint] ePrint surpasses 1000 papers in 2014

  Today is a historic day for ePrint, with our 1000th paper published in 2014. Check out the exciting new 4-digit paper IDs!

04:17 [Pub][ePrint] Cryptanalysis of Full PRIDE Block Cipher, by Yibin Dai and Shaozhen Chen

  PRIDE is a lightweight block ciphers designed by Albrecht et al., appears in CRYPTO 2014. The designers claim that the construction of linear layers is nicely in line with a bit-sliced implementation of the Sbox layer and security. In this paper, we find 8 2-round iterative related-key differential characteristics, which can be used to construct 18-round related-key differentials. Then, by discussing the function $g^{(1)}_r$, we also find 4 2-round iterative related-key differential characteristics with $\\Delta g^{(1)}_r(k_{1,2})=0x80$ and 4 2-round iterative characteristics with $\\Delta g^{(1)}_r(k_{1,2})=0x20$ which cause three weak-key classes. Based on the related-key differentials, we launch related-key differential attack on full PRIDE. The data and time complexity are $2^{39}$ chosen plaintexts and $2^{60}$ encryptions, respectively. Moreover, by using multi related-key differentials, we improve the cryptanalysis, which requires $2^{41.4}$ chosen plaintexts and $2^{44}$ encryptions, respectively. Finally, by using 17-round related-key differentials, the cryptanalysis requires $2^{34}$ plaintexts and $2^{53.7}$ encryptions. These are the first results on full PRIDE.



04:17 [Pub][ePrint] Armadillo: a compilation chain for privacy preserving applications, by Sergiu Carpov and Paul Dubrulle and Renaud Sirdey

  In this work we present Armadillo a compilation chain used for compiling applications written in a high-level language (C++) to work on encrypted data. The back-end of the compilation chain is based on homomorphic encryption. The tool-chain further automatically handle a huge amount of parallelism so as to mitigate the performance overhead of using homomorphic encryption.



04:17 [Pub][ePrint] Controlled Homomorphic Encryption: Definition and Construction, by Yvo Desmedt and Vincenzo Iovino and Giuseppe Persiano and Ivan Visconti

  Fully Homomorphic Encryption schemes (FHEs) and Functional Encryption schemes (FunctEs) have a tremendous impact in Cryptography both for the natural questions that they address and for the wide range of applications in which they have been (sometimes critically) used. In this work we put forth the notion of a Controllable Homomorphic Encryption scheme (CHES), a new primitive that includes features of both FHEs and FunctEs. In a CHES it is possible (similarly to a FHE) to homomorphically evaluate a ciphertext Ct = Enc(m) and a circuit C therefore obtaining Enc(C(m)) but only if (similarly to a FunctE) a token for C has been received from the owner of the secret key. We discuss difficulties in constructing a CHES and then show a construction based on any FunctE.



04:17 [Pub][ePrint] Combining Secret Sharing and Garbled Circuits for Efficient Private IEEE 754 Floating-Point Computations, by Pille Pullonen and Sander Siim

  Two of the major branches in secure multi-party computation research are secret sharing and garbled circuits. This work succeeds in combining these to enable seamlessly switching to the technique more efficient for the required functionality. As an example, we add garbled circuits based IEEE 754 floating-point numbers to a secret sharing environment achieving very high efficiency and the first, to our knowledge, fully IEEE 754 compliant secure floating-point implementation.



04:17 [Pub][ePrint] Constant Round Concurrent Zero-knowledge from Indistinguishability Obfuscation, by Kai-Min Chung and Huijia Lin and Rafael Pass

  We present a constant-round concurrent zero-knowledge protocol for NP. Our protocol relies on the existence of families of collision-resistant hash functions, one-way permutations, and indistinguishability obfuscators for P/poly (with slightly super-polynomial security).



04:17 [Pub][ePrint] Incentivized Outsourced Computation Resistant to Malicious Contractors, by Alptekin Kupcu

  With the rise of Internet computing, outsourcing difficult computational tasks became an important need. Yet, once the computation is outsourced, the job owner loses control, and hence it is crucial to provide guarantees against malicious actions of the contractors involved. Cryptographers have an almost perfect solution, called fully homomorphic encryption, to this problem. This solution hides both the job itself and any inputs to it from the contractors, while still enabling them to perform the necessary computation over the encrypted data. This is a very strong security guarantee, but the current constructions are highly impractical.

In this paper, we propose a different approach to outsourcing computational tasks. We are not concerned with hiding the job or the data, but our main task is to ensure that the job is computed correctly. We also observe that not all contractors are malicious; rather, majority are rational. Thus, our approach brings together elements from cryptography, as well as game theory and mechanism design. We achieve the following results: (1) We incentivize all the rational contractors to perform the outsourced job correctly, (2) we guarantee high fraction (e.g., 99.9%) of correct results even in the existence of a relatively large fraction (e.g., 33%) of malicious irrational contractors in the system, (3) and we show that our system achieves these while being almost as efficient as running the job locally (e.g., with only 3% overhead). Such a high correctness guarantee was not known to be achieved with such efficiency.



04:17 [Pub][ePrint] How Different Electrical Circuits of ECC Designs Influence the Shape of Power Traces measured on FPGA, by Thomas Basmer and Christian Wittke and Zoya Dyka and Peter Langendoerfer

  Side channel and fault attacks take advantage from the fact that the behavior of crypto implementations can be observed and provide hints that simplify revealing keys. These attacks use identical devices either for preparation of attacks or for measurements. By the preparation of attacks the structure and the electrical circuit of devices, that are identical to the target, is analyzed. By side channel attacks usually the same device is used many times for measurements, i.e. measurements on the identical device are made serially in time. Another way is to exploit the difference of side channel leakages; here two identical devices are used parallel, i.e. at the same time. In this paper we investigate the influence of the electrical circuit of a cryptographic implementation on the shape of the resulting power trace, because individualizing of circuits of cryptographic devices can be a new means to prevent attacks that use identical devices. We implemented three different designs that provide exactly the same cryptographic function, i.e. an ECC kP multiplication. For our evaluation we use two different FPGAs. The visualization of the routed design and measurement results show clear differences in the resources consumed as well as in the power traces.



04:17 [Pub][ePrint] Two novel applications of bilinear groups to ABE encryption, by Riccardo Longo and Chiara Marcolla and Massimiliano Sala

  Bilinear groups are often used to create Attribute-Based Encryption (ABE) algorithms.

In particular, they have been used to create an ABE system with multi authorities, but limited to the ciphertext-policy instance.

Here, for the first time, we propose two multi-authority key-policy ABE systems.

In our first proposal, the authorities may be set up in any moment and without any coordination.

A party can simply act as an ABE authority by creating its own public parameters and issuing private keys to the users.

A user can thus encrypt data choosing both a set of attributes and a set of trusted authorities, maintaining full control unless all his chosen authorities collude against him.

In our second system, the authorities are allowed to collaborate to achieve shorter keys and parameters, enhancing the efficiency of encryption and decryption.

We prove our systems secure under algebraic assumptions on the bilinear groups: the bilinear Diffie-Hellmann assumption and an original variation of the former.