Joshua Baron

5PM: Secure pattern matching

In this paper we consider the problem of secure pattern matching that allows single-character wildcards and substring matching in the malicious stand-alone setting. Our protocol, called 5PM, is executed between two parties: Server, holding a text of length n, and Client, holding a pattern of length m to be matched against the text, where our notion of matching is more general than traditionally considered and includes non-binary alphabets, non-binary Hamming distance and non-binary substring matching.5PM is the first secure expressive pattern matching protocol designed to optimize round complexity by carefully specifying the entire protocol round by round. 5PM requires only eight rounds in the malicious static corruptions model. In the malicious model, 5PM requires O((m+n)k2) communication complexity and O(m+n) encryptions, where m is the pattern length and n is the text length. Further, 5PM can hide pattern size with no asymptotic additional costs in either computation or bandwidth.

5PM: secure pattern matching

In this paper we consider the problem of secure pattern matching that allows single character wildcards and substring matching in the malicious (stand-alone) setting. Our protocol, called 5PM, is executed between two parties: Server, holding a text of length n, and Client, holding a pattern of length m to be matched against the text, where our notion of matching is more general and includes non-binary alphabets, non-binary Hamming distance and non-binary substring matching. 5PM is the first protocol with communication complexity sub-linear in circuit size to compute non-binary substring matching in the malicious model (general MPC has communication complexity which is at least linear in the circuit size). 5PM is also the first sublinear protocol to compute non-binary Hamming distance in the malicious model. Additionally, in the honest-but-curious (semi-honest) model, 5PM is asymptotically more efficient than the best known scheme when amortized for applications that require single charcter wildcards or substring pattern matching. 5PM in the malicious model requires O((m+n)k2) bandwidth and O(m+n) encryptions, where m is the pattern length and n is the text length. Further, 5PM can hide pattern size with no asymptotic additional costs in either computation or bandwidth. Finally, 5PM requires only 2 rounds of communication in the honest-but-curious model and 8 rounds in the malicious model. Our techniques reduce pattern matching and generalized Hamming distance problem to a novel linear algebra formulation that allows for generic solutions based on any additively homomorphic encryption. We believe our efficient algebraic techniques are of independent interest.

Communication-Optimal Proactive Secret Sharing for Dynamic Groups

Proactive secret sharing (PSS) schemes are designed for settings where long-term confidentiality of secrets is required, specifically, when all participating parties may eventually be corrupted. PSS schemes periodically refresh secrets and reset corrupted parties to an uncorrupted state; in PSS the corruption threshold of parties is replaced with a corruption rate which cannot be violated. In dynamic proactive secret sharing (DPSS) the group of participating parties can vary during the course of execution. Accordingly, DPSS is ideal when the set of participating parties changes over the lifetime of the secret or where removal of parties is necessary if they become severely corrupted. This paper presents the first DPSS scheme with optimal amortized per-secret communication in the number of parties, n: This paper requires O(1) communication, as compared to \(O(n^4)\) or \(\exp (n)\) in previous work. We present perfectly and statistically secure schemes with near-optimal threshold in each case. We also describe how to construct a communication-efficient dynamic proactively-secure multiparty computation (DPMPC) protocol which achieves the same thresholds.

Performance limitations of compressive sensing for millimeter wave imaging

The authors present an analysis of compressive sensing (CS) as applied to millimeter wave and optical imaging systems, showing that the technique inherently reduces detection efficiency due to reflection and diffraction effects of the underlying electromagnetics. The results show that single-detector imaging approaches that rely on simultaneous detection of multiple spatial modes (i.e., image pixels) require an electrically large detector to maintain high detection efficiency.

On linear-size pseudorandom generators and hardcore functions

We consider the question of constructing pseudorandom generators that simultaneously have linear circuit complexity (in the output length), exponential security (in the seed length), and a large stretch (linear or polynomial in the seed length). We refer to such a pseudorandom generator as an asymptotically optimal PRG. We present a simple construction of an asymptotically optimal PRG from any one-way function f : { 0 , 1 } n ? { 0 , 1 } n which satisfies the following requirements:1.f can be computed by linear-size circuits;2.f is 2 β n -hard to invert, for some constant β 0 ;3.f either has high entropy, in the sense that the min-entropy of f ( x ) on a random input x is at least γn where β / 3 + γ 1 , or alternatively it is regular in the sense that the preimage size of every output of f is fixed. Known constructions of PRGs from one-way functions can do without the entropy or regularity requirements, but they achieve slightly sub-exponential security (Vadhan and Zheng (2012) 27).Our construction relies on a technical result about hardcore functions that may be of independent interest. We obtain a family of hardcore functions H = { h : { 0 , 1 } n ? { 0 , 1 } α n } that can be computed by linear-size circuits for any 2 β n -hard one-way function f : { 0 , 1 } n ? { 0 , 1 } n where β 3 α . Our construction of asymptotically optimal PRGs uses such hardcore functions, which are obtained via linear-size computable affine hash functions (Ishai et al. (2008) 24).

An architecture for a resilient cloud computing infrastructure

This paper proposes an architecture for a resilient cloud computing infrastructure that provably maintains cloud functionality against persistent successful corruptions of cloud nodes. The architecture is composed of a self-healing software mechanism for the entire cloud, as well as hardware-assisted regeneration of compromised (or faulty) nodes from a pristine state. Such an architecture aims to secure critical distributed cloud computations well beyond the current state of the art by tolerating, in a seamless fashion, a continuous rate of successful corruptions up to certain corruption rate limit, e.g., 30% of all cloud nodes may be corrupted within a tunable window of time. The proposed architecture achieves these properties based on a principled separation of distributed task supervision from the computation of user-defined jobs. The task supervision and enduser communication are performed by a new software mechanism called the Control Operations Plane (COP), which builds a trustworthy and resilient, self-healing cloud computing infrastructure out of the underlying untrustworthy and faulty hosts. The COP leverages provably-secure cryptographic protocols that are efficient and robust in the presence of many corrupted participants - such a cloud regularly and unobtrusively refreshes itself by restoring COP nodes from a pristine state at regular intervals.

On Linear-Size Pseudorandom Generators and Hardcore Functions

We consider the question of constructing pseudorandom generators that simultaneously have linear circuit complexity (in the output length), exponential security (in the seed length), and a large stretch (linear or polynomial in the seed length). We refer to such a pseudorandom generator as an asymptotically optimal PRG. We present a simple construction of an asymptotically optimal PRG from any one-way function f:{0,1} n → {0,1} n which satisfies the following requirements:

Nearly simultaneously resettable black-box zero knowledge

An important open question in Cryptography concerns the possibility of achieving secure protocols even in the presence of physical attacks. Here we focus on the case of proof systems where an adversary forces the honest player to re-use its randomness in different executions. In 2009, Deng, Goyal and Sahai [1] constructed a simultaneously resettable non-black-box zero-knowledge argument system that is secure against resetting provers and verifiers. In this work we study the case of the black-box use of the code of the adversary and show a nearly simultaneously resettable black-box zero-knowledge proof systems under standard assumptions. Compared to [1], our protocol is a proof (rather then just argument) system, but requires that the resetting prover can reset the verifier up to a bounded number of times (which is unavoidable for black-box simulation), while the verifier can reset the prover an arbitrary polynomial number of times. The main contribution of our construction is that the round complexity is independent of the above bound. To achieve our result, we construct a constant-round nearly simultaneously resettable coin-flipping protocol that we believe is of independent interest.

Methods for efficient correction of complex noise in outdoor video rate passive millimeter wavelength imagery

Abstract. Passive millimeter wavelength (PMMW) video holds great promise, given its ability to see targets and obstacles through fog, smoke, and rain. However, current imagers produce undesirable complex noise. This can come as a mixture of fast shot (snowlike) noise and a slower-forming circular fixed pattern. Shot noise can be removed by a simple gain style filter. However, this can produce blurring of objects in the scene. To alleviate this, we measure the amount of Bayesian surprise in videos. Bayesian surprise measures feature change in time that is abrupt but cannot be accounted for as shot noise. Surprise is used to attenuate the shot noise filter in locations of high surprise. Since high Bayesian surprise in videos is very salient to observers, this reduces blurring, particularly in places where people visually attend. Fixed pattern noise is removed after the shot noise using a combination of non-uniformity correction and mean image wavelet transformation. The combination allows for online removal of time-varying fixed pattern noise, even when background motion may be absent. It also allows for online adaptation to differing intensities of fixed pattern noise. We also discuss a method for sharpening frames using deconvolution. The fixed pattern and shot noise filters are all efficient, which allows real time video processing of PMMW video. We show several examples of PMMW video with complex noise that is much cleaner as a result of the noise removal. Processed video clearly shows cars, houses, trees, and utility poles at 20 frames per second.