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15:17 [Pub][ePrint] Cryptanalysis of the OKH Authenticated Encryption Scheme, by Peng Wang and Wenling Wu and Liting Zhang

  Alomair proposed a new authenticated encryption scheme OKH at ACNS 2012, and proved the security, i.e. authenticity and privacy, of OKH. Our research shows that it is not the case. We only need one query to break the authenticity of OKH with success probability of $1$, and two queries to break the privacy of OKH with success probability of $1-1/2^n$, where $n$ is the block-length of underlying blockcipher.

15:17 [Pub][ePrint] On the security of two smart-card-based remote user authentication schemes for WSN, by Ding Wang and Chun-guang Ma

  Understanding security failures of cryptographic protocols is the key to both patching existing protocols and designing future schemes. The design of secure and efficient remote user authentication schemes for real-time data access in wireless sensor networks (WSN) is still an open and quite challenging problem, though many schemes have been proposed lately. In this study, we analyze two recent proposals in this research domain. Firstly, Das et al.\'s scheme is scrutinized, demonstrating its vulnerabilities to smart card security breach attack and privileged insider attack, which are among the security objectives pursued in their protocol specification. Then, we investigate a temporal-credential-based password authentication scheme introduced by Xue et al. in 2012. This protocol only involves hash and XOR operations and thus is suitable for the resource-constrained WSN environments where an external user wants to obtain real-time data from the sensor nodes inside WSN. However, notwithstanding their security arguments, we point out that Xue et al.\'s protocol is still vulnerable to smart card security breach attack and privileged insider attack, and fails to provide identity protection. The proposed cryptanalysis discourages any use of the two schemes under investigation in practice and reveals some subtleties and challenges in designing this type of schemes. Besides reporting the security flaws, we put forward a principle that is vital for designing more robust two-factor authentication schemes for WSN.

15:17 [Pub][ePrint] Using Randomizers for Batch Verification of ECDSA Signatures, by Sabyasachi Karati and Abhijit Das and Dipanwita Roychowdhury

  Randomizers are popularly used to prevent various types of attacks on batch-verification schemes. Recently, several algorithms based upon symbolic computation are proposed for the batch verification of ECDSA signatures. In this article, we demonstrate that the concept of randomizers can be easily embedded in these symbolic-computation algorithms. The performance degradation caused by randomizers is comparable with that associated with ECDSA*.

15:17 [Pub][ePrint] New Constructions and Proof Methods for Large Universe Attribute-Based Encryption, by Yannis Rouselakis and Brent Waters

  We propose two large universe Attribute-Based Encryption constructions. In a large universe ABE construction any string can be used as an attribute and attributes need not be enumerated at system setup. Our first construction establishes a novel large universe Ciphertext-Policy ABE scheme on prime order bilinear groups, while the second achieves

a significant efficiency improvement over the large universe Key-Policy ABE systems of Lewko-Waters and Lewko. Both schemes are selectively secure in the standard model under two \"q-type\" assumptions similar to ones used in prior works. Our work brings back \"program and cancel\" techniques to this problem.

We provide implementations and benchmarks of our constructions

in Charm; a programming environment for rapid prototyping of cryptographic primitives.

15:17 [Pub][ePrint] Quantitative Analysis of the Full Bitcoin Transaction Graph, by Dorit Ron and Adi Shamir

  The Bitcoin scheme is a rare example of a large scale global

payment system in which all the transactions are publicly

accessible (but in an anonymous way). We downloaded the full history

of this scheme, and analyzed many statistical properties of its

associated transaction graph. In this paper we answer for the

first time a variety of interesting questions about the typical

behavior of account owners, how they acquire and how they spend

their Bitcoins, the balance of Bitcoins they keep in their

accounts, and how they move Bitcoins between their various

accounts in order to better protect their privacy. In addition, we

isolated all the large transactions in the system, and discovered

that almost all of them are closely related to a single large

transaction that took place in November 2010, even though the

associated users apparently tried to hide this fact with many

strange looking long chains and fork-merge structures in the

transaction graph.

15:17 [Pub][ePrint] ON PROVABLY SECURE CODE-BASED SIGNATURE AND SIGNCRYPTION SCHEME, by Preetha Mathew K and Sachin Vasant and C Pandu Rangan

  Signcryption is a cryptographic protocol that provides authentication and confidentiality as a single primitive at a cost lower than the combined cost of sign and encryption. Due to the improved efficiency, signcryption schemes have found significant applications in areas related to E-commerce. Shor\'s algorithm [22] poses a threat to number-theoretic algorithms, as it can solve the number-theoretic hard problems in polynomial time using quantum computers. Therefore, code-based cryptography offers an exciting alternative to number-theoretic cryptography, as it is not only resistant to quantum algorithms, but also, the base operation (matrix-vector multiplication) is far less computationally intensive

compared to the modular exponentiation required in number-theoretic schemes. Courtois, Finiasz and Sendrier proposed the only practical code-based signature(CFS signature) [7]. It can be used to realise

many cryptographic primitives. But the signature is currently not provably secure due to the existence

of the high rate distinguisher [11]. In this paper, we make use of an alternate key-construct for the CFS

signature, and thus prove its existential unforgeability under chosen message attacks (EUF-CMA). Also,

we propose a code-based signcryption scheme and proved its security. To the best of our knowledge,

this is the first code-based, provably secure signature and signcryption scheme in literature.

15:17 [Pub][ePrint] SHADE: Secure HAmming DistancE computation from oblivious transfer, by Julien Bringer and Herve Chabanne and Alain Patey

  We introduce two new schemes for securely computing Hamming distance in the two-party setting. Our first scheme is a very efficient protocol, based solely on 1-out-of-2 Oblivious Transfer, that achieves full security in the semi-honest setting and one-sided security in the malicious setting. Moreover we show that this protocol is significantly more efficient than the previous proposals, that are either based on garbled circuits or on homomorphic encryption. Our second scheme achieves full security against malicious adversaries and is based on Committed Oblivious Transfer. These protocols have direct applications to secure biometric identification.

05:35 [Event][New] ICEND 2013: 2nd International Conference on e-Technologies and Networks for Development

  Submission: 15 December 2012
Notification: 1 January 2013
From March 4 to March 6
Location: Kuala Lumpur, Malaysia
More Information:

19:49 [Event][New] Africacrypt 2013

  Submission: 31 January 2013
Notification: 15 March 2013
From June 24 to June 26
Location: Cairo, Egypt
More Information:

02:41 [Event][New] NSS 2013: The 7th International Conference on Network and System Security (NSS 2013)

  Submission: 15 December 2012
Notification: 15 February 2013
From June 3 to June 4
Location: Madrid, Spain
More Information:

02:41 [Event][New] ICICS 2013: The 4th International Conference on Information and Communication Systems

  Submission: 1 December 2012
Notification: 20 January 2013
From April 23 to April 25
Location: Irbid, Jordan
More Information: