International Association for Cryptologic Research

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2013-06-18
12:17 [Pub][ePrint] ASICS: Authenticated Key Exchange Security Incorporating Certification Systems, by Colin Boyd and Cas Cremers and Michèle Feltz and Kenneth G. Paterson and Bertram Poettering and Douglas Stebila

  Most security models for authenticated key exchange (AKE) do not explicitly model the associated certification system, which includes the certification authority (CA) and its behaviour. However, there are several well-known and realistic attacks on AKE protocols which exploit various forms of malicious key registration and which therefore lie outside the scope of these models. We provide the first systematic analysis of AKE security incorporating certification systems (ASICS). We define a family of security models that, in addition to allowing different sets of standard AKE adversary queries, also permit the adversary to register arbitrary bitstrings as keys. For this model family we prove generic results that enable the design and verification of protocols that achieve security even if some keys have been produced maliciously. Our approach is applicable to a wide range of models and protocols; as a concrete illustration of its power, we apply it to the CMQV protocol in the natural strengthening of the eCK model to the ASICS setting.



09:43 [Event][New] EBW 2014: The 2nd International Conference on E-Technologies and Business on the Web

  Submission: 20 January 2014
Notification: 15 February 2014
From March 18 to March 20
Location: Kuala Lumpur, Malaysia
More Information: http://sdiwc.net/conferences/2014/ebw2014/


09:43 [Event][New] RWC 2014: Real World Cryptography Workshop 2014

  From January 13 to January 15
Location: New York, United States of America
More Information: http://realworldcrypto.wordpress.com/


09:17 [Forum] [IACR Publication Reform] Re: The speed of science: two case studies by hoerder

  Hi, Christopher, if a paper does not get resubmitted to an IACR venue it doesn\'t imply that it\'s not going to be resubmitted at other venues where IACR members are on the program committee and have to spend time reviewing the re-submission. Depending on how it is crafted, the resubmission policy might just end up shifting the workloads around. Also, Dan raises a valid question: What exactly is a resubmission? How much does a rejected paper have to change to be a new submission? From the CHES community I heard rumors that they\'re considering an journal of their own but instead of papers people have to submit extended abstracts and reviewers act more or less as shepherds. I\'m not sure whether this makes more sense or not, just wanted to point out that there are more possibilities. And that both halfs of IACR are leading very similar discussion in parallel (as far as I can see it). A friend of mine who is doing solid state physics was just complaining about stupid reviewers a week ago and the way he described their model, it sounded quite like the proposed proceedings of the IACR. I reckon that there will never be a perfect system and that quite a lot depends on the little details for each system and the degree of flexibility they offer. What I\'d truly like to see is a more scientific debate about it. Right now, we have suggestions, examples and hypotheses but no hard data, not even a detailed comparison of two or three submission models that are currently used by other disciplines (of similar size) who are reasonably happy with their system. Please don\'t get me wrong, I see the need to "grow up" and the suggestions, examples and hypotheses that I\'ve seen so far all make valid points but all that I see emerging from it is that it\'s not simple. Maybe it would be useful to get outside support from people who do metascience. (I\'m sure that someone\'s doing just that. What else do we have social scientists for?) Cheers, Simon Hoerder From: 2013-18-06 08:52:59 (UTC)

09:17 [Pub][ePrint] Chosen Ciphertext Secure Keyed-Homomorphic Public-Key Encryption, by Keita Emura and Goichiro Hanaoka and Koji Nuida and Go Ohtake and Takahiro Matsuda and Shota Yamada

  In homomorphic encryption schemes, anyone can perform homomorphic operations, and therefore, it is difficult to manage when, where and by whom they are performed. In addition, the property that anyone can \\lq\\lq freely\'\' perform the operation inevitably means that ciphertexts are malleable, and it is well-known that adaptive chosen ciphertext (CCA) security and the homomorphic property can never be achieved simultaneously.

In this paper, we show that CCA security and the homomorphic property can be simultaneously handled in situations that the user(s) who can perform homomorphic operations on encrypted data should be controlled/limited, and propose a new concept of homomorphic public-key encryption, which we call \\emph{keyed-homomorphic public-key encryption} (KH-PKE). By introducing a secret key for homomorphic operations, we can control who is allowed to perform the homomorphic operation. To construct KH-PKE schemes, we introduce a new concept, a \\emph{homomorphic transitional universal hash family}, and present a number of KH-PKE schemes through hash proof systems. We also present a practical construction of KH-PKE from the DDH assumption. For $\\ell$-bit security, our DDH-based scheme yields only $\\ell$-bit longer ciphertext size than that of the Cramer-Shoup PKE scheme.



09:17 [Pub][ePrint] Key Recovery Attacks on 3-round Even-Mansour, 8-step LED-128, and Full $\\mbox{AES}^{2}$, by Itai Dinur and Orr Dunkelman and Nathan Keller and Adi Shamir

  The Even-Mansour (EM) encryption scheme received a lot of attention in the last couple of years due to its exceptional simplicity and tight security proofs.

The original $1$-round construction was naturally generalized into $r$-round structures with one key, two alternating keys, and completely independent keys.

In this paper we describe the first key recovery attack on the one-key 3-round version of EM which is asymptotically faster than exhaustive search

(in the sense that its running time is $o(2^n)$ rather than $O(2^n)$ for an $n$-bit key).

We then use the new cryptanalytic techniques in order to improve the best known

attacks on several concrete EM-like schemes. In the case of LED-128, the best previously known attack could only be applied to 6 of its 12 steps. In this paper we develop a new attack which increases the number of attacked steps to 8, is slightly faster than the previous attack on 6 steps, and uses about a thousand times less data.

Finally, we describe the first attack on the full $\\mbox{AES}^{2}$ (which uses two complete AES-128 encryptions and three independent $128$-bit keys, and looks exceptionally strong) which is about 7 times faster than a standard meet-in-the-middle attack, thus violating its security claim.



09:17 [Pub][ePrint] Efficient Simultaneous Privately and Publicly Verifiable Robust Provable Data Possession from Elliptic Curves, by Christian Hanser and Daniel Slamanig

  When outsourcing large sets of data to the cloud, it is desirable for clients to efficiently check, whether all outsourced data is still retrievable at any later point in time without requiring to download all of it. Provable data possession (PDP)/proofs of retrievability (PoR), for which various constructions exist, are concepts to solve this issue. Interestingly, by now, no PDP/PoR scheme leading to an efficient construction supporting both private and public verifiability simultaneously is known. In particular, this means that up to now all PDP/PoR schemes either allow public or private verifiability exclusively, since different setup procedures and metadata sets are required. However, supporting both variants simultaneously seems interesting, as publicly verifiable schemes are far less efficient than privately verifiable ones. In this paper, we propose the first simultaneous privately and publicly verifiable (robust) PDP protocol, which allows the data owner to use the more efficient private verification and anyone else to run the public verification algorithm. Our construction, which is based on elliptic curves, achieves this, as it uses the same setup procedure and the same metadata set for private and public verifiability. We provide a rigorous security analysis and prove our construction secure in the random oracle model under the assumption that the elliptic curve discrete logarithm problem is intractable. We give detailed comparisons with the most efficient existing approaches for either private or public verifiability with our proposed scheme in terms of storage and communication overhead, as well as computational effort for the client and the server. Our analysis shows that for choices of parameters, which are relevant for practical applications, our construction outperforms all existing privately and publicly verifiable schemes significantly. This means, that even when our construction is used for either private or public verifiability alone, it still outperforms the most efficient constructions known, which is particularly appealing in the public verifiability setting.



09:17 [Pub][ePrint] Strongly Secure One-round Group Authenticated Key Exchange in the Standard Model, by Yong Li and Zheng Yang

  One-round group authenticated key exchange (GAKE) protocols typically provide implicit authentication and appealing bind-width efficiency. As a special case of GAKE -- the pairing-based one-round tripartite authenticated key exchange (3AKE), recently gains much attention of research community due to its strong security. Several pairing-based one-round 3AKE protocols have recently been proposed to achieve provable security in the g-eCK model. In contrast to earlier GAKE models, the g-eCK model particularly formulates the security properties regarding resilience to the leakage of various combinations of long-term key and ephemeral session state, and provision of weak perfect forward secrecy in a single model. However, the g-eCK security proofs of previous protocols are only given under the random oracle model. In this work, we give a new construction for pairing-based one-round 3AKE protocol which is provably secure in the g-eCK model without random oracles. Security of proposed protocol is reduced to the hardness of Cube Bilinear Decisional Diffie-Hellman (CBDDH) problem for symmetric pairing. We also extend the proposed 3AKE scheme to a GAKE scheme with more than three group members, based on multilinear maps. We prove g-eCK security of our GAKE scheme in the standard model under the natural multilinear generalization of the CBDDH assumption.



09:17 [Pub][ePrint] A Public Key Cryptoscheme Using the Bit-pair Method, by Shenghui Su and Maozhi Xu and Shuwang Lu

  The authors give the definition of a bit-pair shadow, and design the three algorithms of a public key cryptoscheme called JUNA which regards a bit-pair as an operation unit, and is based on the multivariate permutation problem (MPP) and the anomalous subset product problem (ASPP). Then, demonstrate the correctness of the decryption algorithm, deduce the probability that a plaintext solution is nonunique is nearly zero, and analyze the security of the cryptoscheme against extracting a private key from a public key, and recovering a plaintext from a ciphertext on the assumption that IFP, DLP, and SSP can be solved efficiently. Besides, give the conversion from the ASPP to the anomalous subset sum problem (ASSP) through a discrete logarithm. The facts show the bit-pair method increases the density of a related ASSP knapsack with D > 1, and decreases the length of modulus of the cryptoscheme with lg M = 384, 464, 544, or 640 corresponding to n = 80, 96, 112, or 128.



09:17 [Pub][ePrint] Pickle: A HASH Design, by Lan Luo and Yalan Ye and Zehui Qu and Sharon Goldberg and Xan Du

  For make the cryptography design eatable and popular,

we design the pickle HASH carefully. The pickle can deal large

data into HASH value with 1024bytes block quickly. There are

normal mode and operation mode of pickle from Keccak and

Shabal respectively. The nonlinear transformation is from 3fish of

Skein, which is only use up the MIX function. The pickle is speed

up because of no memory operation mode. The core function P is 8

times MIX without linear permutation and subkey involving in. So,

the full pickle is similar to the interlace code plus a little bit

nonlinear function. The nonlinear character is equal to the Skein

so that we consider it\'s secure. The output from filter function

strong the linear character of pickle.



09:17 [Pub][ePrint] On the Practical Security of a Leakage Resilient Masking Scheme, by Emmanuel Prouff and Matthieu Rivain and Thomas Roche

  At TCC 2012, Dziembowski and Faust show how to construct leakage resilient circuits using secret sharing based on the inner product [2]. At Asiacrypt 2012, Ballash et al. turned the latter construction into an efficient masking scheme and they apply it to protect an implementation of AES against side-channel attacks [1]. The so-called Inner-Product masking (IPmasking for short) was claimed to be secure with respect to two different security models: the $\\lambda$-limited security model (Section 4 of [1]), and the dth-order security model (see definitions p.8 of [1]). In the former model, the security proof makes sense for a sharing dimension $n > 130$ which is acknowledged impractical by the authors. In the latter model, the scheme is claimed secure up to the order $d = n-1$. In this note, we contradict the dth-order security claim by exhibiting a 1st-order flaw in the masking algorithm for any chosen sharing dimension n.