Non-malleable codes for space-bounded tampering

Non-malleable codes—introduced by Dziembowski, Pietrzak and Wichs at ICS 2010—are key-less coding schemes in which mauling attempts to an encoding of a given message, w.r.t. some class of tampering adversaries, result in a decoded value that is either identical or unrelated to the original message. Such codes are very useful for protecting arbitrary cryptographic primitives against tampering attacks against the memory. Clearly, non-malleability is hopeless if the class of tampering adversaries includes the decoding and encoding algorithm. To circumvent this obstacle, the majority of past research focused on designing non-malleable codes for various tampering classes, albeit assuming that the adversary is unable to decode. Nonetheless, in many concrete settings, this assumption is not realistic

The chaining lemma and its application

We present a new information-theoretic result which we call the Chaining Lemma. It considers a so-called “chain” of random variables, defined by a source distribution X(0)with high min-entropy and a number (say, t in total) of arbitrary functions (T1,…, Tt) which are applied in succession to that source to generate the chain (Formula presented). Intuitively, the Chaining Lemma guarantees that, if the chain is not too long, then either (i) the entire chain is “highly random”, in that every variable has high min-entropy; or (ii) it is possible to find a point j (1 ≤ j ≤ t) in the chain such that, conditioned on the end of the chain i.e. (Formula presented), the preceding part (Formula presented) remains highly random. We think this is an interesting information-theoretic result which is intuitive but nevertheless requires rigorous case-analysis to prove. We believe that the above lemma will find applications in cryptography. We give an example of this, namely we show an application of the lemma to protect essentially any cryptographic scheme against memory tampering attacks. We allow several tampering requests, the tampering functions can be arbitrary, however, they must be chosen from a bounded size set of functions that is fixed a prior

Implementation of mean-timing and subsequent logic functions on an FPGA

This article describes the implementation of a mean-timer and coincidence logic on a Virtex-5 FPGA for trigger purposes in a particle physics experiment. The novel feature is that the mean-timing and the coincidence logic are not synchronized with a clock which allows for a higher resolution of approximately 400 ps, not limited by a clock frequency.Comment: 15 pages, 11 figure

Efficient public-key cryptography with bounded leakage and tamper resilience

We revisit the question of constructing public-key encryption and signature schemes with security in the presence of bounded leakage and tampering memory attacks. For signatures we obtain the first construction in the standard model; for public-key encryption we obtain the first construction free of pairing (avoiding non-interactive zero-knowledge proofs). Our constructions are based on generic building blocks, and, as we show, also admit efficient instantiations under fairly standard number-theoretic assumptions. The model of bounded tamper resistance was recently put forward by Damgård et al. (Asiacrypt 2013) as an attractive path to achieve security against arbitrary memory tampering attacks without making hardware assumptions (such as the existence of a protected self-destruct or key-update mechanism), the only restriction being on the number of allowed tampering attempts (which is a parameter of the scheme). This allows to circumvent known impossibility results for unrestricted tampering (Gennaro et al., TCC 2010), while still being able to capture realistic tampering attack

Experimental studies of the NaCs 12(0+) [7¹Σ+] state

We present results from experimental studies of the 11(0+) and 12(0+) electronic states of the NaCs molecule. An optical-optical double resonance method is used to obtain Doppler-free excitation spectra. Selected data from the 11(0+) and 12(0+) high-lying electronic states are used to obtain Rydberg-Klein-Rees and Inverse Perturbation Approach potential energy curves. Interactions between these two electronic states are evident in the patterns observed in the bound-bound and bound-free fluorescence spectra. A model, based on two separate interaction mechanisms, is presented to describe how the wavefunctions of the two states mix. The electronic parts of the wavefunctions interact via spin-orbit coupling, while the individual rotation-vibration levels interact via a second mechanism, which is likely to be non-adiabatic coupling. A modified version of the BCONT program was used to simulate resolved fluorescence from both upper states. Parameters of the model that describe the two interaction mechanisms were varied until simulations were able to adequately reproduce experimental spectra.National Science Foundation (U.S.) (grant no. PHY-0968898)National Science Foundation (U.S.) (grant no. PHY-1403060)National Science Foundation (U.S.) (grant no. CHE–1361865

Survey of Canada Goose Feces for Presence of \u3cem\u3eGiardia\u3c/em\u3e

As resident Canada goose (Branta canadensis) populations increase throughout North America, so do the health and environmental risks associated with goose feces. Previous studies suggest that goose feces may be a conduit for transmitting Giardia, a protozoan that is parasitic to humans. We surveyed fecal droppings from free-ranging resident Canada geese for Giardia spp. at 9 sites in the Triangle area (Raleigh, Durham, and Chapel Hill) of North Carolina in 2007 and 2008. Samples (n = 234) were tested using the ProSpect® Giardia EZ Microplate Assay, and there were no positives. Our results indicate that risk of zoonotic giardiasis from Canada goose feces in the Triangle area of North Carolina is low

High fidelity progressive reinforcement learning for agile maneuvering UAVs

In this work, we present a high fidelity model based progressive reinforcement learning method for control system design for an agile maneuvering UAV. Our work relies on a simulation-based training and testing environment for doing software-in-the-loop (SIL), hardware-in-the-loop (HIL) and integrated flight testing within photo-realistic virtual reality (VR) environment. Through progressive learning with the high fidelity agent and environment models, the guidance and control policies build agile maneuvering based on fundamental control laws. First, we provide insight on development of high fidelity mathematical models using frequency domain system identification. These models are later used to design reinforcement learning based adaptive flight control laws allowing the vehicle to be controlled over a wide range of operating conditions covering model changes on operating conditions such as payload, voltage and damage to actuators and electronic speed controllers (ESCs). We later design outer flight guidance and control laws. Our current work and progress is summarized in this work

Leakage-resilient non-malleable codes

A recent trend in cryptography is to construct cryptosystems that are secure against physical attacks. Such attacks are usually divided into two classes: the \emph{leakage} attacks in which the adversary obtains some information about the internal state of the machine, and the \emph{tampering} attacks where the adversary can modify this state. One of the popular tools used to provide tamper-resistance are the \emph{non-malleable codes} introduced by Dziembowski, Pietrzak and Wichs (ICS 2010). These codes can be defined in several variants, but arguably the most natural of them are the information-theoretically secure codes in the k-split-state model (the most desired case being k=2). Such codes were constucted recently by Aggarwal et al.~(STOC 2014). Unfortunately, unlike the earlier, computationally-secure constructions (Liu and Lysyanskaya, CRYPTO 2012) these codes are not known to be resilient to leakage. This is unsatisfactory, since in practice one always aims at providing resilience against both leakage and tampering (especially considering tampering without leakage is problematic, since the leakage attacks are usually much easier to perform than the tampering attacks). In this paper we close this gap by showing a non-malleable code in the $2$-split state model that is secure against leaking almost a $1/12$-th fraction of the bits from the codeword (in the bounded-leakage model). This is achieved via a generic transformation that takes as input any non-malleable code (\Enc,\Dec) in the $2$-split state model, and constructs out of it another non-malleable code (\Enc',\Dec') in the $2$-split state model that is additionally leakage-resilient. The rate of (\Enc',\Dec') is linear in the rate of (\Enc,\Dec). Our construction requires that \Dec is \emph{symmetric}, i.e., for all $x, y$, it is the case that \Dec(x,y) = \Dec(y,x), but this property holds for all currently known information-theoretically secure codes in the $2$-split state model. In particular, we can apply our transformation to the code of Aggarwal et al., obtaining the first leakage-resilient code secure in the split-state model. Our transformation can be applied to other codes (in particular it can also be applied to a recent code of Aggarwal, Dodis, Kazana and Obremski constructed in the work subsequent to this one)