International Association for Cryptologic Research

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16:18 [Job][New] Post-Doc, Mathematical Institute, Oxford

  This is a 3-year Postdoctoral Research Fellowship in Post-Quantum Cryptography. Candidates should have previous post-doctoral experience, and expertise in cryptography. Knowledge of quantum computing is desirable but not essential.

15:44 [Job][New] Professorship in Cyber Security and Privacy, School of Informatics, University of Edinburgh, UK

  Informatics at Edinburgh is recruiting a new (full) professor in the general area of Cyber Security and Privacy. Specific topics of interest include applied cryptography, systems security, network security, but experts in other areas are encouraged to apply.

Our department is the largest, most research productive Informatics and Computer Science department in the UK; we are also one of the top places for undergraduate teaching. We are looking for an outstanding research leader and educator who can help us grow our existing expertise in the security and privacy area.

Please check the information at the link below and the online vacancy details page for full details of the job specification. We encourage making informal contact before application.

22:02 [Event][New] CANS 2015: The 14th International Conference on Cryptology and Network Security

  Submission: 19 June 2015
Notification: 31 August 2015
From December 8 to December 12
Location: Marrakesh, Morocco
More Information:

06:17 [Pub][ePrint] Secure Multi-Party Computation with Identifiable Abort, by Yuval Ishai and Rafail Ostrovsky and Vassilis Zikas

  Protocols for secure multi-party computation (MPC) that resist a dishonest majority are susceptible to \"denial of service\" attacks, allowing even a single malicious party to force the protocol to abort. In this work, we initiate a systematic study of the more robust notion of security with identifiable abort, which leverages the effect of an abort by forcing, upon abort, at least one malicious party to reveal its identity.

We present the first information-theoretic MPC protocol which is secure with identifiable abort (in short ID-MPC) using a correlated randomness setup. This complements a negative result of Ishai et al. (TCC 2012) which rules out information-theoretic ID-MPC in the OT-hybrid model, thereby showing that pairwise correlated randomness is insufficient for information- theoretic ID-MPC.

In the standard model (i.e., without a correlated randomness setup), we present the first computationally secure ID-MPC protocol making black-box use of a standard cryptographic primitive, namely an (adaptively secure) oblivious transfer (OT) protocol. This provides a more efficient alternative to existing ID-MPC protocols, such as the GMW protocol, that make a non-black-box use of the underlying primitives.

As a theoretically interesting side note, our black-box ID-MPC provides an example for a natural cryptographic task that can be realized using a black-box access to an OT protocol but cannot be realized unconditionally using an ideal OT oracle.

06:17 [Pub][ePrint] Cryptanalysis Of An Authenticated Image Encryption Scheme Based On Chaotic Maps And Memory Cellular Automata, by Saeideh Kabirirad and Hamideh Hajiabadi

  Recently an image encryption scheme based on chaotic maps and memory cellular automata has been proposed. In this paper, the security of the scheme is evaluated and it is demonstrated that the scheme can be broken by chosen plain-text attack. Having one or more monochrome plain-images and their corresponding cipher-images, a part of key-stream can be retrieved. Furthermore, it is discovered that the scheme can be broken by brute search attack with efficient time complexity, and it is also vulnerable to differential attack. Meanwhile, we provide experimental results to support the proposed attacks and suggest several improvements to make scheme stronger.

06:17 [Pub][ePrint] Some results on Sprout, by Subhadeep Banik

  Sprout is a lightweight stream cipher proposed by Armknecht and Mikhalev at FSE 2015. It has a Grain-like structure with two State Registers of size 40 bits each, which is exactly half the state size

of Grain v1. In spite of this, the cipher does not appear to lose in security against generic Time-Memory-Data Tradeoff attacks due to the novelty of its design. In this paper, we first present improved results on Key Recovery with partial knowledge of the internal state. We show that if 50 of the 80 bits of the internal state are guessed then the remaining bits along with the Secret Key can be found in a reasonable time using a SAT solver. Thereafter we show that it is possible to perform a distinguishing attack on the full Sprout stream cipher in the multiple IV setting using around $2^{40}$ randomly chosen IVs on an average. The attack requires around $2^{48}$ bits of memory. Thereafter we will show that for every Secret Key, there exist around $2^{30}$ IVs for which the LFSR used in Sprout enters the all zero state during the Keystream generating phase. Using this observation, we will first show that it is possible to enumerate Key-IV pairs that produce keystream bits with period as small as 80. We will then outline a simple Key recovery attack that takes time equivalent to $2^{66.7}$ encryptions with negligible memory requirement. This although is not the best attack reported against this cipher in terms of the Time complexity, it is the best in terms of the memory required to perform the attack.

06:17 [Pub][ePrint] Strongly Secure Authenticated Key Exchange from Ideal Lattices, by Xiaopeng Yang and Wenping Ma

  In this paper, we propose an efficient and practical authenticated key exchange (AKE) protocol from ideal lattices, which is well-designed and has some similarity to the HMQV protocol. Using the hardness of the graded discrete logarithm (GDL) problem and graded decisional Diffie-Hellman (GCDH) problem, the proposed protocol is provably secure in the extended Canetti-Krawczyk model.

06:17 [Pub][ePrint] Non-malleability under Selective Opening Attacks: Implication and Separation, by Zhengan Huang and Shengli Liu and Xianping Mao and Kefei Chen

  We formalize the security notions of non-malleability under selective opening attacks (NM-SO security) in two approaches: the indistinguishability-based approach and the simulationbased approach. We explore the relations between NM-SO security notions and the known selective

opening security notions, and the relations between NM-SO security notions and the standard non-malleability notions.

06:17 [Pub][ePrint] Leakage-Resilient Cryptography over Large Finite Fields: Theory and Practice, by Marcin Andrychowicz and Daniel Masny and Edoardo Persichetti

  Information leakage is a major concern in modern day IT-security. In fact, a malicious user is often able to extract

information about private values from the computation performed on the

devices. In specific settings, such as RFID, where a low computational complexity is required, it is hard to apply standard techniques to achieve resilience against this kind of attacks.

In this paper, we present a framework to make cryptographic

primitives based on large finite fields robust against information leakage

with a bounded computational cost.

The approach makes use

of the inner product extractor and guarantees security in the presence of

leakage in a widely accepted model. Furthermore, we show how to apply the proposed

techniques to the authentication protocol Lapin, and we compare it to existing


06:17 [Pub][ePrint] Practical Divisible E-Cash, by Patrick Märtens

  Divisible e-cash systems allow a user to withdraw a wallet containing K coins and to spend k < K + 1 coins in a single operation, respectively. Independent of the new work of Canard, Pointcheval, Sanders and Traoré (Proceedings of PKC \'15) we present a practical and secure divisible e-cash system in which the bandwidth of each protocol is constant while the system fulfills the standard security

requirements (especially which is unforgeable and truly anonymous) in the random oracle model. In other existing divisible e-cash systems that are truly anonymous, either the bandwidth of withdrawing

depends on K or the bandwidth of spending depends on k. Moreover, using some techniques of the work of Canard, Pointcheval, Sanders and Traoré we are also able to prove the security in the standard model.

Furthermore, we show an efficient attack against the unforgeability of Canard and Gouget\'s divisible e-cash scheme (FC \'10).

Finally, we extend our scheme to a divisible e-cash system that provides withdrawing and spending of an arbitrary value of coins (not necessarily a power of two) and give an extension to a fair e-cash


06:17 [Pub][ePrint] Point Decomposition Problem in Binary Elliptic Curves, by Koray Karabina

  We analyze the point decomposition problem (PDP) in binary elliptic curves. It is known that PDP in an elliptic curve group can be reduced to solving a particular system of multivariate non-linear system of equations derived from the so called Semaev summation polynomials.

We modify the underlying system of equations by introducing some auxiliary variables. We argue that the trade-off between lowering the degree of Semaev polynomials and increasing the number of variables is worth.