*13:17* [Pub][ePrint]
Perfect Structure on the Edge of Chaos, by Nir Bitansky and Omer Paneth and Daniel Wichs
We construct trapdoor permutations based on (sub-exponential) indistinguishability obfuscation and one-way functions, thereby providing the first candidate that is not based on the hardness of factoring.Our construction shows that even highly structured primitives, such as trapdoor permutations, can be potentially based on hardness assumptions with noisy structures such as those used in candidate constructions of indistinguishability obfuscation. It also suggest a possible way to construct trapdoor permutations that resist quantum attacks, and that their hardness may be based on problems outside the complexity class SZK - indeed, while factoring-based candidates do not possess such security, future constructions of indistinguishability obfuscation might.

As a corollary, we eliminate the need to assume trapdoor permutations and injective one-way function in many recent constructions based on indistinguishability obfuscation.

*13:17* [Pub][ePrint]
Block-wise Non-Malleable Codes, by Nishanth Chandran and Vipul Goyal and Pratyay Mukherjee and Omkant Pandey and Jalaj Upadhyay
Non-malleable codes, introduced by Dziembowski, Pietrzak, and Wichs (ICS \'10), provide the guarantee that if a codeword $c$ of a message $m$, is modified by a tampering function $f$ to $c\'$, then $c\'$ either decodes to $m$ or to ``something unrelated\" to $m$. It is known that non-malleable codes cannot exist for the class of all tampering functions and hence a lot of work has focused on explicitly constructing such codes against a large and natural class of tampering functions. One such popular, but restricted, class is the so-called \\emph{split-state} model in which the tampering function operates on different parts of the codeword \\emph{independently}.In this work, we remove the above restriction by considering a stronger adversarial model that we call the {\\em block-wise tampering} model. In this model, the adversary can tamper every block of the codeword, with the only restriction being that he can tamper every block at most once. As an example, if a codeword $c = (c_1,c_2)$, then the first tampering function $f_1$ could produce a tampered part $c_1\'=f_1(c_1)$ and the second tampering function $f_2$ could produce $c_2\' = f_2(c_1,c_2)$ which can depend on {\\em both} $c_2$ and $c_1$. An example is when the blocks are being sent one by one and the adversary must temper and send the first block before the second block comes along.

- Surprisingly, defining non-malleability in the block-wise tampering model is challenging. Our first contribution is that of providing a relaxed, yet meaningful definition of non-malleability for this model. Unfortunately, we show, that even this notion is impossible to achieve in the information-theoretic setting (i.e., when the tampering functions can be unbounded) and we must turn our attention towards computationally bounded adversaries.

- Next, we provide an interesting connection between block-wise non-malleable codes and non-malleable commitments. We show that any block-wise non-malleable code can be converted into a non-malleable (wrt opening) commitment. In the other direction, we show that any non-interactive non-malleable (wrt opening) commitment can be used to construct a block-wise non-malleable code (with $2$ blocks).

- While the above transformation gives us a construction of a block-wise non-malleable code, it is based on the highly non-standard assumption of adaptive one-way functions (which can only be realized based on assumptions such as Oracle DDH). As our main result, we show, how to construct a block-wise non-malleable code from any sub-exponentially hard one-way permutations. Our techniques, quite surprisingly, also give rise to a non-malleable commitment scheme (secure against so-called synchronizing adversaries), in which {\\em only} the committer sends messages. We believe this result to be of independent interest.

*17:15* [Job][New]
Full-time PhD or Postdoc positions in the area of Wireless Sensor Networks (WSN) Security , *University of Mannheim, Germany*
The positions is funded by the German Research Foundation (DFG) in the project WSNSec (Wireless Sensor Network Security), being a collaboration with Universtiy of Erlangen-Nuremberg. ========

This position ocuses on the theoretical aspects of WSNSec:

- Formalization of attacker models and security goals

- Cryptanalysis of existing cryptographic protocols

- Development of provably secure cryptographic protocols

========

The candidate should have the following qualifications:

• Master degree (or an equivalent degree) in Mathematics, Computer Science or a related discipline

• Experience in cryptography

• Knowledge in the modeling and formal analysis of cryptographic protocols is helpful, but not required

*10:18* [Job][Update]
Postdoc Positions in Cloud-Computing and Storage Security, *IBM Research - Zurich*
Postdoc Positions in Cloud-Computing and Storage SecurityThe cloud storage and cloud solutions security research teams at IBM Research - Zurich are looking for outstanding researchers to strengthen their activities covering security mechanisms for storage systems and cloud computing. Topics include cryptographic schemes addressing privacy and authenticity, software-defined storage systems, and distributed secure protocols.

The successful candidate will hold a PhD in computer science or a related field, with an excellent record of publications and other accomplishments in the field. A good understanding of cryptographic techniques and a strong background in storage systems, file systems, databases, distributed systems and operating systems is beneficial. Candidates must have a strong desire and proven ability to conduct research independently, invent new ideas, implement them in real systems, and publish the results of their work.

The highly motivated, creative individual will join a multi-disciplinary research team to design and implement advanced mechanisms for protecting cloud computing and storage systems.

IBM is committed to diversity at the workplace. With us, you will find an open, multicultural environment. Excellent, flexible working arrangements enable both women and men to strike the desired balance between their professional development and their personal lives.

Multiple positions are available with starting dates in 2015. For obtaining more information about the topic, please contact: Dr. Christian Cachin and mention \\\"Cloud security position\\\" in the subject line.

There is no specific closing date, even though the form here asks for a date.

To apply, please send your CV including contact information for two references by email to: *cloudsec (at) zurich.ibm.co*m

IBM Research - Zurich

http://www.research.ibm.com/labs/zurich/

*07:00* [Job][New]
Ph.D., *DOCOMO Communications Lab. Europe GmbH, Munich*
Designed and developed solutions that will allow for seamless multimedia service provisioning and transparently and securely using heterogeneous network technologies.- Researched for various cryptographic algorithms.

- Recommended a combination of AES and RSA algorithms for encrypted data transmission between chat client peers of a secure chat communication over a messenger.

- Designed and implemented the cryptographic algorithm and the messenger prototype using Java platform.

- Made use of Java for developing the messenger GUI, event handling in GUI through implementing Interfaces, establishing connection between server and client.

*04:17* [Pub][ePrint]
Provably weak instances of Ring-LWE, by Yara Elias and Kristin E. Lauter and Ekin Ozman and Katherine E. Stange
The ring and polynomial learning with errors problems (Ring-LWE and Poly-LWE) have been proposed as hard problems to form the basis for cryptosystems, and various security reductions to hard lattice problems have been presented. So far these problems have been stated for general (number) rings but have only been closely examined for cyclotomic number rings. In this paper, we state and examine the Ring-LWE problem for general number rings and demonstrate provably weak instances of Ring-LWE. We construct an explicit family of number fields for which we have an efficient attack. We demonstrate the attack in both theory and practice, providing code and running times for the attack. The attack runs in time linear in q, where q is the modulus.Our attack is based on the attack on Poly-LWE which was presented in [EHL]. We extend the EHL-attack to apply to a larger class of number fields, and show how it applies to attack Ring-LWE for a heuristically large class of fields. Certain Ring-LWE instances can be transformed into Poly-LWE instances without distorting the error too much, and thus provide the first weak instances of the Ring-LWE problem. We also provide additional examples of fields which are vulnerable to our attacks on Poly-LWE, including power-of-2 cyclotomic fields, presented using the minimal polynomial of $\\zeta_{2^n} \\pm 1$.

*04:17* [Pub][ePrint]
Dynamic Searchable Symmetric Encryption with Minimal Leakage and Efficient Updates on Commodity Hardware, by Attila A. Yavuz and Jorge Guajardo
Dynamic Searchable Symmetric Encryption (DSSE) enables a client to perform keyword queries and update operations on the encrypted file collections. DSSE has several important applications such as privacy-preserving data outsourcing for computing clouds. In this paper, we developed a new parallelizable DSSE scheme that achieves the highest privacy among all compared alternatives with low information leakage, non-interactive and efficient updates, compact client storage, low server storage for large file-keyword pairs with an easy design and implementation. Our scheme achieves these desirable properties with a very simple data structure (i.e., a bit matrix supported with two static hash tables) that enables efficient yet secure search/update operations on it. We formally prove that our scheme is secure (in random oracle model) and demonstrated that it is fully practical with large number of file-keyword pairs even with an implementation on simple hardware configurations.