International Association for Cryptologic Research

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14:43 [Job][New] Ph.D. / M.Sc. Scholarships and Summer Internship, Cryptography, Security, and Privacy Research Group, Koç University, Istanbul, Turkey

  Cryptography, Security & Privacy Research Group at Koç University has multiple openings for both M.Sc. and Ph.D. level applications. All accepted applicants will receive competitive scholarships including tuition waiver, housing, monthly stipend, computer, travel support, etc.

For more information about our group and projects, visit

For questions, contact Asst. Prof. Alptekin Küpçü

For applying online, and questions about the application-process, visit

For summer internship opportunities, visit

08:00 [Job][New] Professor in Cryptography (W1 - non-tenured), Ruhr-Universität Bochum, Germany

  The Ruhr-Universität Bochum (RUB) is one of Germany’s leading research universities with more than 50 scientists working in IT-security and cryptography. The Faculty of Mathematics invites applications for the position of a Junior Professor (W1) in Cryptography to start as soon as possible.

The future holder of the position will represent the subject in research and teaching.

We are seeking a candidate with an excellent research record in cryptography, in particular in theoretical cryptography, provable security, protocols, or secure multi-party computation.

The position is non-tenured with an initial appointment for 3 years, and renewable for another 3 years after a positive mid-term review.

Candidates for the professorship are expected to have strong leadership qualities, particularly

• excellent level of commitment in academic teaching

• willingness to participate in interdisciplinary research

• willingness and ability to attract externally funded research projects

• or to contribute to joint research projects of the department.

09:17 [Pub][ePrint] LCPR: High Performance Compression Algorithm for Lattice-Based Signatures and Schnorr-like Constructions, by Rachid El Bansarkhani and Johannes Buchmann

  We present a novel and generic construction of a lossless compression algorithm for Schnorr-like signatures utilizing publicly accessible randomness. This strategy is from a mathematical and algorithmic point of view very interesting, since it is closely related to vector quantization techniques used for audio and video compression. Conceptually, exploiting public randomness in order to reduce the signature size has never been considered in cryptographic applications. This opens new directions for improving existing signature schemes. We illustrate the applicability of our compression algorithm using the examples of current-state-of-the-art signature schemes such as the efficient constructions due to Lyubashevsky et al. and the GPV signature scheme instantiated with the efficient trapdoor construction from Micciancio and Peikert. Both schemes benefit from increasing the main security parameter $n$, which is positively correlated with the compression rate measuring the amount of storage savings. For instance, GPV signatures admit improvement factors of approximately $\\lg n$ implying compression rates of about $65$\\% for practical parameters without suffering loss of information or decrease in security, meaning that the original signature can always be recovered from its compressed state. Similarly, for signatures generated according to the scheme due to G\\\"uneysu et al. we achieve compression rates of approximately $60$\\% and even $73$\\%, when combining with previous compression algorithms. As a further interesting result, we propose a generic unrestricted aggregate signature scheme.

09:17 [Pub][ePrint] Shadow Numbers Public Key Encryption, by John Almeida

  The present public key encryption in this paper involves the use of two values and they are the shadows values of a base value, and the base value is derived from the two shadows values. Whenever two integer values (first shadow value and second shadow value) are multiplied producing a product value and the value of one is subtracted from the product value a first base value is derived and it is the first base value of the two shadows values. The derived first base value may be divided by any divisor that it may be divided with which produces a positive integer quotient result and zero for the remainder. All values that are used in the division and the quotient result are bases values for the chosen shadow value-pair. Then one of the base values is chosen along with the two chosen shadows values and they comprise a triplet values that represent the public key to encrypt a message and the private key to decrypt the encrypted message.

09:17 [Pub][ePrint] Private Predictive Analysis on Encrypted Medical Data, by Joppe W. Bos and Kristin Lauter and Michael Naehrig

  Increasingly, confidential medical records are being stored in data centers hosted by hospitals or large companies. As sophisticated algorithms for predictive analysis on medical data continue to be developed, it is likely that, in the future, more and more computation will be done on private patient data. While encryption provides a tool for assuring the privacy of medical information, it limits the functionality for operating on such data. Conventional

encryption methods used today provide only very restricted possibilities or none at all to operate on encrypted data without decrypting it first. Homomorphic encryption provides a tool for

handling such computations on encrypted data, without decrypting the data, and without even needing the decryption key.

In this paper, we discuss possible application scenarios for homomorphic encryption in order to ensure privacy of sensitive medical data. We describe how to privately conduct predictive analysis tasks on encrypted data using homomorphic encryption. As a proof of concept, we present a working implementation of a prediction service running in the cloud (hosted on Microsoft\'s Windows Azure), which takes as input private encrypted health data, and returns the probability of suffering cardiovascular disease in encrypted form. Since the cloud service uses homomorphic encryption, it makes this prediction while handling only encrypted data, learning nothing about

the submitted confidential medical data.

09:17 [Pub][ePrint] Related Randomness Attacks for Public Key Encryption, by Kenneth G. Paterson and Jacob C.N. Schuldt and Dale L. Sibborn

  Several recent and high-profile incidents give cause to believe that randomness failures of various kinds are endemic in deployed cryptographic systems. In the face of this, it behoves cryptographic researchers to develop methods to immunise - to the extent that it is possible - cryptographic schemes against such failures. This paper considers the practically-motivated situation where an adversary is able to force a public key encryption scheme to reuse random values, and functions of those values, in encryption computations involving adversarially chosen public keys and messages. It presents a security model appropriate to this situation, along with variants of this model. It also provides necessary conditions on the set of functions used in order to attain this security notation, and demonstrates that these conditions are also sufficient in the Random Oracle Model. Further standard model constructions achieving weaker security notions are also given, with these constructions having interesting connections to other primitives including: pseudo-random functions that are secure in the related key attack setting; Correlated Input Secure hash functions; and public key encryption schemes that are secure in the auxiliary input setting (this being a special type of leakage resilience).

09:17 [Pub][ePrint] A Tamper and Leakage Resilient Random Access Machine, by Sebastian Faust and Pratyay Mukherjee and Jesper Buus Nielsen and Daniele Venturi

  We present a ``universal\'\' Random Access Machine (RAM in short) for tamper and leakage resilient computation. The RAM has one CPU that accesses three storages (called disks in the following), two of them are secret, while the other one is public. The CPU has constant size for each fixed value of security parameter $k$. We construct a compiler for this architecture which transforms any keyed primitive into a RAM program where the key is encoded and stored on the two secret disks and the instructions for evaluating the functionality are stored on the public disk.

The compiled program tolerates arbitrary independent tampering of the disks. That is, the adversary can tamper with the intermediate values produced by the CPU, and the program code of the compiled primitive on the public disk. In addition, it tolerates bounded independent leakage from the disks and continuous leakage from the communication channels between the disks and the CPU.

Although it is required that the circuit of the CPU is tamper and leakage proof, its design is independent of the actual primitive being computed and its internal storage is non-persistent, i.e., all secret registers are reset between invocations. Hence, our result can be interpreted as reducing the problem of shielding arbitrary complex computations to protecting a single, simple and ``universal\'\' component. As a main ingredient of our construction we use continuous

non-malleable codes that satisfy certain additional properties.

09:17 [Pub][ePrint] Public-Coin Concurrent Zero-Knowledge in Logarithmic Rounds, by Yi Deng


09:17 [Pub][ePrint] A Strong and Efficient Certificateless Digital Signature Scheme, by Mohammed Alfateh Hassouna and Mohsin Hashim

  This paper extends the certificateless public key infrastructure model that was proposed by Hassouna et al by proposing new digital signature scheme to provide true non-repudiation,

the proposed signature scheme is short and efficient, it is also has strength point that the KGC has no contribution in signature generation/verification process, therefore any compromise

of the KGC does not affect the non-repudiation service of the system. Furthermore, even the KGC cannot do signature forgery by (temporary) replacing the user\'s public key.

09:17 [Pub][ePrint] Formal Analysis of Chaumian Mix Nets with Randomized Partial Checking, by Ralf Kuesters and Tomasz Truderung and Andreas Vogt

  Mix nets with randomized partial checking (RPC mix nets) have been introduced by Jakobsson, Juels, and Rivest as particularly simple and efficient verifiable mix nets. These mix nets have been used in several implementations of prominent e-voting systems to provide vote privacy and verifiability. In RPC mix nets, higher efficiency is traded for a lower level of privacy and verifiability. However, these mix nets have never undergone a rigorous formal analysis. Recently, Kahazei and Wikstroem even pointed out several severe problems in the original proposal and in implementations of RPC mix nets in e-voting systems, both for so-called re-encryption and Chaumian RPC mix nets. While Kahazei and Wikstroem proposed several fixes, the security status of Chaumian RPC mix nets (with the fixes applied) has been left open; re-encryption RPC mix nets, as they suggest, should not be used at all.

In this paper, we provide the first formal security analysis of Chaumian RPC mix nets. We propose security definitions that allow one to measure the level of privacy and verifiability RPC mix nets offer, and then based on these definitions, carry out a rigorous analysis. Altogether, our results show that these mix nets provide a reasonable level of privacy and verifiability, and that they are still an interesting option for the use in e-voting systems.

00:19 [News] Mass Surveillance and the Subversion of Cryptography


Statement of Principle from the IACR Membership on Mass Surveillance and the Subversion of Cryptography

The membership of the IACR repudiates mass surveillance and the undermining of cryptographic solutions and standards. Population-wide surveillance threatens democracy and human dignity. We call for expediting research and deployment of effective techniques to protect personal privacy against governmental and corporate overreach.