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07:17 [Pub][ePrint] Constructing Differentially 4-uniform Permutations over GF(2^{2k}) from the Inverse Function Revisited, by Yongqiang Li and Mingsheng Wang and Yuyin Yu

  Constructing S-boxes with low differential uniformity and high

nonlinearity is of cardinal significance in cryptography. In the

present paper, we show that numerous differentially 4-uniform

permutations over GF(2^{2k}) can be constructed by composing

the inverse function and cycles over GF(2^{2k}). Two sufficient

conditions are given, which ensure that the differential uniformity

of the corresponding compositions equals 4. A lower bound on

nonlinearity is also given for permutations constructed with the

method in the present paper. Moreover, up to CCZ-equivalence, a new

differentially 4-uniform permutation with the best known

nonlinearity over GF(2^{2k}) with $k$ odd is constructed. For

some special cycles, necessary and sufficient conditions are given

such that the corresponding compositions are differentially


13:47 [Event][New] LATINCRYPT 2014: Third International Conference on Cryptology and Information Security

  Submission: 5 July 2014
Notification: 23 August 2014
From September 17 to September 19
Location: Florian´┐Żpolis, Brazil
More Information:

08:54 [Event][New] IWSEC 2013: The 8th International Workshop on Security (Poster Session)

  Submission: 15 November 2013
Notification: 16 November 2013
From November 18 to November 20
Location: Okinawa, Japan
More Information:

08:50 [Job][New] Security Engineer, CloudFlare Inc., San Francisco, CA, USA, the Northern Hemisphere


CloudFlare is looking for a talented security engineer to join our team. We are working on a number of ambitious projects to secure the web and protect our customers from threats of all sorts. The role of security engineer at CloudFlare is more that of a builder than a breaker. You will have to approach problems with creativity and flexibility and be able to identify and use the best tools for the job or build better ones from scratch. At CloudFlare, we are serious about protecting our customers and advancing the state of the art in computer security.


Strong systems-level programming skills?

Deep understanding of networking protocols (TCP/IP, SSL/TLS, DNS)

Experience with cryptographic libraries and APIs

Expert in C/C++ and performance analysis

Proficiency in Go and/or Lua or willingness to learn

Strong understanding of security concepts (key management, access control, authentication)

Understanding of Linux internals

Interest in advancements in security and cryptography

Bonus Points:

Contributions to the open source community

Experience implementing production-grade cryptographic algorithms

Knowledge or expertise in White-box cryptography

Experience with DNSSEC

Familiarity with compilers or code generation tools

Experience with cryptographic hardware (TPM, HSM, etc.)

Healthy sense of paranoia

08:48 [Job][New] Ph.D. Scholarships, University of Salerno, Italy

  to appear

07:17 [Pub][ePrint] Deep Attacks of a Certificateless Signature Scheme, by Bo Yang and Zhao Yang and Zibi Xiao and Shougui Li

  Certificateless public key cryptography is an attractive paradigm since it eliminates the use of certificates in traditional public key cryptography and alleviates the inherent key escrow problem in identity-based cryptography. Recently, Xiong et al. proposed a certificateless signature scheme and proved that their scheme is existentially unforgeable against adaptive chosen message attack under the random oracle model. He et al. pointed out that Xiong et al.\'s scheme is insecure against the Type II adversary. But, their forged signatures are not random, and their improved scheme has the same security defects as Xiong et al.\'s scheme. In this paper, we present two malicious-but-passive KGC attack methods on Xiong et al.\'s scheme and our results show that their scheme is insecure against malicious-but-passive KGC attack.

07:17 [Pub][ePrint] The Realm of the Pairings, by Diego F. Aranha and Paulo S. L. M. Barreto and Patrick Longa and Jefferson E. Ricardini

  Bilinear maps, or pairings, initially proposed in a cryptologic context for cryptanalytic purposes, proved afterward to be an amazingly flexible and useful tool for the construction of cryptosystems with unique features. Yet, they are notoriously hard to implement efficiently, so that their effective deployment requires a careful choice of parameters and algorithms. In this paper we review the evolution of pairing-based cryptosystems, the development of efficient algorithms and the state of the art in pairing computation, and the challenges yet to be addressed on the subject, while also presenting some new algorithmic and implementation refinements in affine and projective coordinates.

07:17 [Pub][ePrint] Amplifying Privacy in Privacy Amplification, by Divesh Aggarwal and Yevgeniy Dodis and Zahra Jafargholi and Eric Miles and Leonid Reyzin

  We study a classical problem of privacy amplification, where two parties Alice and Bob share a weak secret X of min-entropy k, and wish to agree on secret key $R$ of length $m$ over a public communication channel completely controlled by a computationally unbounded attacker Eve.

Despite being extensively studied in the literature, the design of (efficient) \"optimal\" privacy amplification protocols is still open. Part of the reason is that there are quite a few important efficiency/security goals when designing privacy amplification protocols. The most basic such goal is to minimize the {\\em entropy loss} L=k-m, and it is known that the optimal value for L=O(\\lambda), where \\eps=2^{-\\lambda} is the desired security of the protocol. Other important considerations include (1) minimizing the number of communication rounds, (2) achieving strongest security notion called {\\em post-application robustness}, and (3) ensuring that the protocol $P$ does not leak some ``useful information\'\' about the source $X$ (this is called {\\em source privacy}). Additionally,

when trying to extract a key R which is much shorter than the source length |X| (and, often, the min-entropy bound k), \"Goal (0)\" of minimizing the entropy loss is replaced by asking (4) if P can be made {\\em locally computable} (meaning it reads only O(|R|) bits of X; this is called the {\\em Bounded Retrieval Model} (BRM)), and/or (5) if P can be sequentially run to extract the optimal number t = \\Theta(k/\\lambda) of session keys R_1,...,R_t of length m=O(\\lambda) each.

As a result, {\\em all} existing protocols in the literature fail to achieve at least two of Goals (0)-(3) (or, when |R|

07:17 [Pub][ePrint] Verifiable Set Operations over Outsourced Databases, by Ran Canetti and Omer Paneth and Dimitrios Papadopoulos and Nikos Triandopoulos

  We study the problem of verifiable delegation of computation over

outsourced data, whereby a powerful worker maintains a large data

structure for a weak client in a verifiable way. Compared to the

well-studied problem of verifiable computation, this setting imposes

additional difficulties since the verifier needs to verify consistency

of updates succinctly and without maintaining large state. In particular,existing general solutions are far from practical in this setting.

We present a scheme for verifiable evaluation of hierarchical set

operations (unions, intersections and set-differences) applied to a

collection of dynamically changing sets of elements from a given

domain. That is, we consider two types of queries issued by the

client: updates (insertions and deletions) and data queries, which

consist of ``circuits\'\' of unions, intersections, and set-differences

on the current collection of sets.

This type of queries comes up in database queries, keyword search and

numerous other applications, and indeed our scheme can be effectively

used in such scenarios. The verification cost incurred is proportional

only to the size of the final outcome set and to the size of the query, and is independent of the cardinalities of the involved sets. The cost of updates is optimal ($O(1)$ modular operations per update).

Our construction extends that of [Papamanthou et al., Crypto 2011]

and relies on a modified version of the \\emph{extractable collision-resistant hash function} (ECRH) construction, introduced in [Bitansky et al., ITCS 2012] that can be used to succinctly hash univariate polynomials.

07:17 [Pub][ePrint] Mobile Transaction over NFC and GSM, by Muhammad Qasim Saeed and Pardis Pourghomi

  Although NFC mobile services have great potential for growth, they have raised a number of issues which are of concern to researchers and are preventing the wide adoption of this technology within society. Dynamic relationships of NFC ecosystem players in an NFC transaction process make them partners in a way that sometimes requires that they share access permission to applications that are running in the service environment. One of the technologies that can be used to ensure secure NFC transactions is cloud computing. This offers a wider range of advantages than the use of a Secure Element (SE) as a single entity in an NFC enabled mobile phone. In this paper, we propose a protocol for NFC mobile payments based on cloud Wallet model. In our protocol, the SE in the mobile device is used for customer authentication whereas the customer\'s banking credentials are stored in a cloud under the control of the Mobile Network Operator (MNO). The proposed protocol eliminates the requirement for a shared secret between the Point of Sale (PoS) and the MNO before execution of the protocol, a mandatory requirement in the earlier version of this protocol. This makes it more practicable and user friendly. A detailed analysis of the protocol discusses multiple attack scenarios.

07:17 [Pub][ePrint] Homomorphic Authenticated Encryption Secure Against Chosen-Ciphertext Attack, by Chihong Joo and Aaram Yun

  We study homomorphic authenticated encryption, where privacy

and authenticity of data are protected simultaneously. We define homomorphic versions

of various security notions for privacy and authenticity, and investigate

relations between them. In particular, we show that it is possible to

give a natural definition of IND-CCA for homomorphic authenticated encryption, unlike

the case of homomorphic encryption. Also, we construct a homomorphic

authenticated encryption scheme supporting arithmetic circuits on $\\ZZ_Q$

for smooth modulus $Q$, which is chosen-ciphertext secure both for privacy

and authenticity. Our scheme is based on the error-free approximate GCD assumption.