DOCSLIB.ORG

Garbled Circuits Via Structured Encryption Seny Kamara Lei Wei 1 Microsoft Research UNC-Chapel Hill

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Garbled Circuits Via Structured Encryption Seny Kamara Lei Wei 1 Microsoft Research UNC-Chapel Hill Garbled Circuits via Structured Encryption Seny Kamara Lei Wei 1 Microsoft Research UNC-Chapel Hill Abstract. The garbled circuit technique transforms a circuit in such a way that it can be evaluated on encrypted inputs. Garbled circuits were originally introduced by Yao (FOCS '86) for the purpose of secure two-party computation but have since found many applications. In this work, we consider the problem of designing special-purpose gar- bled circuits, which are garbled circuits that handle only a specific class of functionalities. Special-purpose constructions are usually smaller than general-purpose ones and lead to more efficient two-party protocols. We propose a design framework for constructing special-purpose garbled circuits based on structured encryption schemes, which are encryption schemes that encrypt data structures in such a way that they can be queried through the use of a token. Using our framework, we show how to design more efficient garbled circuits for several graph-based func- tionalities (with applications to online social network analysis), Boolean circuits, deterministic finite automata, and branching programs. 1 Introduction Yao's garbled circuit technique transforms circuits in such a way that they can be evaluated on encrypted inputs. While garbled circuits were originally intro- duced for the purpose of two-party secure function evaluation (SFE) [19], they have since found many applications, some of which include the design of ho- momorphic encryption schemes, one-time programs, circular-secure encryption, non-interactive verifiable computation, functional encryption, and single-server- aided SFE. At a high level, the garbled circuit technique consists of: (1) a garbling proce- dure that transforms a circuit C that computes a function f, and a set of inputs x = (x1; : : : ; xn) into a garbled circuit Ce and an encoded input xe = (xe1;:::; xen); (2) an evaluation procedure that computes a garbled output ye given Ce and xe; and (3) a decoding procedure that, given ye and a set of decoding keys dk re- turns f(x). The main security property provided by garbled circuits is input privacy, which guarantees that, given (Ce; xe; dk), no information about x is re- vealed by the garbled circuit evaluation beyond what can be inferred from f(x). As shown by Yao, combining garbled circuits with oblivious transfer results in constant-round two-party SFE secure against semi-honest adversaries. The importance of the garbled circuit technique in cryptography can be at- tributed to several factors, including its security properties, its relative efficiency and, most importantly, its generality. In fact, like fully-homomorphic encryption, garbled circuits are one of the few general-purpose primitives in cryptography. 1Work done while at Microsoft Research. While generality is crucial for establishing completeness theorems and for un- derstanding the power of cryptographic techniques, it is well-known that it often comes at the price of efficiency. In fact, it is common for special-purpose con- structions (i.e., constructions that handle only a a sub-class of functionalities) to be more efficient than general-purpose constructions. Our contributions. In this work, we consider the problem of designing special- purpose garbling schemes. Given the importance of garbled circuits and the effi- ciency improvements enjoyed by special-purpose constructions, this is a natural and well-motivated problem. We make the following contributions. We introduce a general framework for designing special-purpose garbling schemes. Our framework is based on a connection between garbled circuits and the notion of structured encryption [8] which is a generalization of index-based searchable symmetric encryption (SSE) [18,10,7,9]. Roughly speaking, a struc- tured encryption scheme encrypts a data structure in such a way that it can be queried through the use of a query-specific token that does not reveal in- formation about the query. Our approach essentially reduces the problem of designing special-purpose garbled circuits to the problem of designing struc- tured encryption schemes. Consequently, improvements in either the efficiency or functionality of structured encryption can lead to similar improvements in the design of special-purpose two-party protocols in the semi-honest model and other cryptographic primitives that rely on input-private garbled circuits. While our main contributions are conceptual, we demonstrate the utility of our approach by constructing special-purpose garbling schemes for several useful functionalities. For example, using our framework with the structured encryption schemes of [8], we get special-purpose garbling schemes (and therefore two-party protocols) for several graph-based functionalities that have applications to online social networks. In addition, in the full version of this work we use our framework to construct garbling schemes for other functionalities like branching programs (BP), deterministic finite automata (DFA) and even Boolean circuits. In all cases, the garbled circuits resulting from our approach are more efficient (i.e., either smaller or with faster evaluation) than the garbled circuits that would result from applying Yao's general-purpose construction. The main building block we need to handle DFAs, BPs and Boolean circuits is a matrix encryption scheme that supports lookups, i.e., a structured encryption scheme that encrypts matrices in such a way that a location (i; j) can be queried using a token. While such a scheme is described in [8], that particular construc- tion is not appropriate for our purposes. The problem is that the scheme from [8] is only 1-dimensional in the sense that it generates a single token for a location (i; j) in the matrix. For our purposes, however, we need a 2-dimensional scheme that generates two independent tokens, i.e., one for i and one for j that can be combined to lookup location (i; j). We show how to construct such a scheme based on the 1-dimensional construction of [8] and pseudo-random synthesizers [17]. 1.1 Background on Structured Encryption Several variants of structured encryption were described in [8] but for our pur- poses we need the structure-only variant which only encrypts data structures as opposed to the standard variant which also encrypts messages. A struc- tured encryption scheme is a tuple of four polynomial-time algorithms SE = (Gen; Enc; Token; Querye) such that Gen is a probabilistic algorithm that takes as input a security parameter k and outputs a private key K. Let T be an abstract data type that maps queries q from a query space Q to an answer a from a response space R. Enc is a probabilistic algorithm that takes as input a key K, a data structure δ 2 T and outputs an encrypted data structure γ. Token is a (possibly probabilistic) algorithm that takes as input a private key K and a query q 2 Q and outputs a token τ. Querye is a deterministic algorithm that takes as input an encrypted data structure γ and a token τ and outputs an answer a 2 R. Informally, a structured encryption scheme is secure against chosen-query attacks (CQA1) if no useful information about q and δ can be recovered from γ and τ beyond what can be deduced from a. We say that a structured encryption scheme is secure against adaptive chosen-query attacks (CQA2) if this holds even when queries are made adaptively (i.e., as a function of the encrypted data structure γ and the results of previous queries and tokens). As a concrete example, consider a graph encryption scheme Graph = (Gen; Enc; Token; Neighe) that supports neighbor queries (we refer the reader to [8] for a concrete construction). With such a scheme one can encrypt the edges E of a graph G = (V; E) by computing γ Enc(K; E). A token for a vertex v 2 V can be created as τ Token(K; v) and the neighbors of v, denoted Γ (v), can be recovered by computing Neighe(γ; τ). Associative structured encryption. For our purposes, we need associative struc- tured encryption schemes which allow one to associate arbitrary strings to each output. So, with respect to our previous example, an associative graph encryp- tion scheme supporting neighbor queries would: (1) allow the encryptor to as- sociate arbitrary strings to each vertex of the graph during the encryption step; and (2) reveal these strings whenever the associated vertex is in Γ (v). More precisely, in addition to the secret key sk and the edges E, the Enc algorithm would also take as input a set of strings (sv1 ; : : : ; svjV j), where svi is associated with vertex vi. Then, the algorithm Neighe would return, in addition to Γ (v), the set fswgw2Γ (v). Due to space restrictions, we refer the reader to [8] for formal definitions of (associative) structured encryption and of the relevant security definitions. 1.2 Overview of our Framework At a high level, our framework consists of two steps. In the first step, the function f is represented as a structured circuit which is a circuit-like computational model where each gate g can query a data structure δ and where the input and output wires of g carry queries for the structures of g and g's descendent, respectively. Our notion of structured circuits is reminiscent of Naor and Nissim's circuits with lookup tables [16] though, in our setting, the contents of the data structure cannot be set during computation. In the second step, at a very high level, the structured circuit is garbled by encrypting each data structure δ with an appropriate structured encryption scheme. These encrypted structures are viewed as the garbled gates and the tokens used to query them are viewed as the encoded wire values. Note that the functionality and security properties needed to construct a garbled gate are precisely what is provided by associative structured encryption schemes.
Load more

Recommended publications
  • Reusable Garbled Gates for New Fully Homomorphic Encryption Service Xu an Wang* Fatos Xhafa Jianfeng Ma Yunfei Cao and Dianhua T
    Int. J. Web and Grid Services, Vol. X, No. Y, XXXX Reusable garbled gates for new fully homomorphic encryption service Xu An Wang* School of Telecommunications Engineering, Xidian University, Xi’an, China and Key Laboratory of Information and Network Security, Engineering University of Chinese Armed Police Force, Xi’an, China Email: [email protected] *Corresponding author Fatos Xhafa Department of Computer Science, Technical University of Catalonia, Barcelona, Spain Email: [email protected] Jianfeng Ma School of Cyber Engineering, Xidian University, Shaanxi, China Email: [email protected] Yunfei Cao and Dianhua Tang Science and Technology on Communication Security Laboratory, Chengdu, China Email: [email protected] Email: [email protected] Abstract: In this paper, we propose a novel way to provide a fully homomorphic encryption service, namely by using garbled circuits. From a high level perspective, Garbled circuits and fully homomorphic encryption, both aim at implementing complex computation on ciphertexts. We define a new cryptographic primitive named reusable garbled gate, which comes from the area of garbled circuits, then based on this new primitive we show that it is very easy to construct a fully homomorphic encryption. However, the instantiation of reusable garbled gates is rather difficult, in fact, we can only instantiate this new primitive based on indistinguishable obfuscation. Furthermore, reusable garbled gates can be a core component for constructing the reusable garbled circuits, which can reduce the communication complexity Copyright © 200X Inderscience Enterprises Ltd. X.A. Wang et al. of them from O(n) to O(1). We believe that reusable garbled gates promise a new way to provide fully homomorphic encryption and reusable garbled circuits service fast.
    [Show full text]
  • Reusable Garbled Circuit Implementation of AES to Avoid Power Analysis Attacks Venkata Lakshmi Sudheera Bommakanti Clemson University
    Clemson University TigerPrints All Theses Theses 8-2017 Reusable Garbled Circuit Implementation of AES to Avoid Power Analysis Attacks Venkata Lakshmi Sudheera Bommakanti Clemson University Follow this and additional works at: https://tigerprints.clemson.edu/all_theses Recommended Citation Bommakanti, Venkata Lakshmi Sudheera, "Reusable Garbled Circuit Implementation of AES to Avoid Power Analysis Attacks" (2017). All Theses. 2751. https://tigerprints.clemson.edu/all_theses/2751 This Thesis is brought to you for free and open access by the Theses at TigerPrints. It has been accepted for inclusion in All Theses by an authorized administrator of TigerPrints. For more information, please contact [email protected]. Reusable Garbled Circuit Implementation of AES to Avoid Power Analysis Attacks A Thesis Presented to the Graduate School of Clemson University In Partial Fulfillment of the Requirements for the Degree Master of Science Electrical Engineering by Venkata Lakshmi Sudheera Bommakanti August 2017 Accepted by: Dr. Richard Brooks, Committee Chair Dr. Richard Groff Dr. Rajendra Singh Abstract Unintended side-channel leaks can be exploited by attackers and achieved quickly, and using relatively inexpensive equipment. Cloud providers aren’t equipped to provide assurances of security against such attacks. One most well- known and effective of the side-channel attack is on information leaked through power consumption. Differential Power Analysis (DPA) can extract a secret key by measuring the power used while a device is executing the any algorithm. This research explores the susceptibility of current implementations of Circuit Garbling to power analysis attacks and a simple variant to obfuscate functionality and randomize the power consumption reusing the garbling keys and the garbled gates.
    [Show full text]
  • Privacy Preserving Computations Accelerated Using FPGA Overlays
    Privacy Preserving Computations Accelerated using FPGA Overlays A Dissertation Presented by Xin Fang to The Department of Electrical and Computer Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Computer Engineering Northeastern University Boston, Massachusetts August 2017 To my family. i Contents List of Figures v List of Tables vi Acknowledgments vii Abstract of the Dissertation ix 1 Introduction 1 1.1 Garbled Circuits . 1 1.1.1 An Example: Computing Average Blood Pressure . 2 1.2 Heterogeneous Reconfigurable Computing . 3 1.3 Contributions . 3 1.4 Remainder of the Dissertation . 5 2 Background 6 2.1 Garbled Circuits . 6 2.1.1 Garbled Circuits Overview . 7 2.1.2 Garbling Phase . 8 2.1.3 Evaluation Phase . 10 2.1.4 Optimization . 11 2.2 SHA-1 Algorithm . 12 2.3 Field-Programmable Gate Array . 13 2.3.1 FPGA Architecture . 13 2.3.2 FPGA Overlays . 14 2.3.3 Heterogeneous Computing Platform using FPGAs . 16 2.3.4 ProceV Board . 17 2.4 Related Work . 17 2.4.1 Garbled Circuit Algorithm Research . 17 2.4.2 Garbled Circuit Implementation . 19 2.4.3 Garbled Circuit Acceleration . 20 ii 3 System Design Methodology 23 3.1 Garbled Circuit Generation System . 24 3.2 Software Structure . 26 3.2.1 Problem Generation . 26 3.2.2 Layer Extractor . 30 3.2.3 Problem Parser . 31 3.2.4 Host Code Generation . 32 3.3 Simulation of Garbled Circuit Generation . 33 3.3.1 FPGA Overlay Architecture . 33 3.3.2 Garbled Circuit AND Overlay Cell .
    [Show full text]
  • Improved Garbled Circuit: Free XOR Gates and Applications
    Improved Garbled Circuit: Free XOR Gates and Applications Vladimir Kolesnikov1 and Thomas Schneider2? 1 Bell Laboratories, 600 Mountain Ave. Murray Hill, NJ 07974, USA [email protected] 2 Horst G¨ortzInstitute for IT-Security, Ruhr-University Bochum, Germany [email protected] Abstract. We present a new garbled circuit construction for two-party secure function evaluation (SFE). In our one-round protocol, XOR gates are evaluated \for free", which results in the corresponding improvement over the best garbled circuit implementations (e.g. Fairplay [19]). We build permutation networks [26] and Universal Circuits (UC) [25] almost exclusively of XOR gates; this results in a factor of up to 4 im- provement (in both computation and communication) of their SFE. We also improve integer addition and equality testing by factor of up to 2. We rely on the Random Oracle (RO) assumption. Our constructions are proven secure in the semi-honest model. 1 Introduction Two-party general secure function evaluation (SFE) allows two parties to evalu- ate any function on their respective inputs x and y, while maintaining privacy of both x and y. SFE is (justifiably) a subject of immense amount of research, e.g. [27,28,17]. Efficient SFE algorithms enable a variety of electronic transactions, previously impossible due to mutual mistrust of participants. Examples include auctions [21,6,8,4], contract signing [7], distributed database mining [12,16], etc. As computation and communication resources have increased, SFE has become truly practical for common use. Fairplay [19] is a full-fledged implementation of generic two-party SFE with malicious players.
    [Show full text]
  • Garbled Protocols and Two-Round MPC from Bilinear Maps
    58th Annual IEEE Symposium on Foundations of Computer Science Garbled Protocols and Two-Round MPC from Bilinear Maps Sanjam Garg Akshayaram Srinivasan Dept. of Computer Science Dept. of Computer Science University of California, Berkeley University of California, Berkeley Berkeley, USA Berkeley, USA Email: [email protected] Email: [email protected] Abstract—In this paper, we initiate the study of garbled (OT) protocol [57], [2], [51], [40] gives an easy solution to protocols — a generalization of Yao’s garbled circuits construc- the problem of (semi-honest) two-round secure computation tion to distributed protocols. More specifically, in a garbled in the two-party setting. However, the same problem for protocol construction, each party can independently generate a garbled protocol component along with pairs of input the multiparty setting turns out to be much harder. Beaver, labels. Additionally, it generates an encoding of its input. The Micali and Rogaway [7] show that garbled circuits can be evaluation procedure takes as input the set of all garbled used to realize a constant round multi-party computation protocol components and the labels corresponding to the input protocol. However, unlike the two-party case, this protocol encodings of all parties and outputs the entire transcript of the is not two rounds. distributed protocol. We provide constructions for garbling arbitrary protocols A. Garbled Protocols based on standard computational assumptions on bilinear maps (in the common random string model). Next, using In this paper, we introduce a generalization of Yao’s garbled protocols we obtain a general compiler that compresses construction from circuits to distributed protocols. We next any arbitrary round multiparty secure computation protocol elaborate on (i) what it means to garble a protocol, (ii) why into a two-round UC secure protocol.
    [Show full text]
  • Private Set Intersection: Are Garbled Circuits Better Than Custom Protocols?
    Private Set Intersection: Are Garbled Circuits Better than Custom Protocols? Yan Huang David Evans Jonathan Katz University of Virginia University of Maryland http://MightBeEvil.org Abstract PSI for post-processing). Many other examples are pro- vided by De Cristofaro et al. [9]. Cryptographic protocols for Private Set Intersection (PSI) Because of its importance and wide applicability, many are the basis for many important privacy-preserving ap- protocols for PSI and its variants have been proposed [7– plications. Over the past few years, intensive research has 11, 14, 15, 20, 24]. All these works develop custom PSI been devoted to designing custom protocols for PSI based protocols using asymmetric cryptography, usually with on homomorphic encryption and other public-key tech- the explicit remark that they do so because solving PSI niques, apparently due to the belief that solutions using via generic techniques (such as garbled-circuit proto- 1 generic approaches would be impractical. This paper ex- cols [39]) would be impractical. However, this claim has plores the validity of that belief. We develop three classes never been substantiated. of protocols targeted to different set sizes and domains, all The belief that generic techniques for solving PSI are based on Yao’s generic garbled-circuit method. We then inefficient may stem from several factors: a general feel- compare the performance of our protocols to the fastest ing that generic protocols are inherently slow and that custom PSI protocols in the literature. Our results show garbled circuits do not scale, or perhaps the belief that that a careful application of garbled circuits leads to solu- computing the intersection of two sets of size n requires tions that can run on million-element sets on typical desk- Q(n2)-size circuits since all pairs of elements must be tops, and that can be competitive with the fastest custom compared.
    [Show full text]
  • Reducing Garbled Circuit Size While Preserving Circuit Gate Privacy ⋆
    Reducing Garbled Circuit Size While Preserving Circuit Gate Privacy ? Yongge Wang1 and Qutaibah m. Malluhi2 1 Department of SIS, UNC Charlotte, USA [email protected] 2 Department of CS, Qatar University, Qatar [email protected] Abstract. Yao's garbled circuits have been extensively used in Secure Function Evaluations (SFE). Several improvements have been proposed to improve the efficiency of garbled circuits. Kolesnikov and Schneider (2008) proposed the free-XOR technique. Naor, Pinkas, and Sumner (1999) introduced garbled row-reduction technique GRR3 to reduce each garbled gate to three ciphertexts, Pinkas et al (2009) proposed GRR2, and Zahur, Rosulek, and Evans (2015) introduced a half-gates technique to design free-XOR compatible GRR2. The GRR2, half-gates, and free- XOR garbling schemes improve efficiency by leaking locations of XOR gates in the circuit. This kind of information leakage is acceptable for SFE protocols though it maybe be unacceptable for other protocols such as Private Function Evaluation (PFE). For example, these techniques could not be used to improve the efficiency of existing non-universal- circuit-based constant round PFE protocols. The first result of this paper is a Gate Privacy preserving Garbled Row Reduction technique GPGRR2 for designing garbled circuits with at most two ciphertexts for each gar- bled gate. Compared with state-of-the-art gate-privacy-preserving gar- bling scheme GRR3, the scheme GPGRR2 reduces the garbled circuit size by a factor of at least 33%. The second result is the design of a linear (over integers) garbling scheme to garble a single odd gate to one ciphertext. Zahur, Rosulek, and Evans (2015) proved that a linear gar- bling scheme garbles each odd gate to at least 2 ciphertexts.
    [Show full text]
  • A Gentle Introduction to Yao's Garbled Circuits
    A Gentle Introduction to Yao’s Garbled Circuits Sophia Yakoubov Boston Univeristy Abstract. This is a short, gentle introduction to the Yao’s Garbled Circuits construction and recent optimizations, as well as the garbled circuit definitions. Keywords: Yao’s Garbled Circuits Table of Contents Recap of Yao’s Garbled Circuits :::::::::::::::::::::::::::::::::::: 1 Sophia Yakoubov 1 Yao’s Garbled Circuits: Background..............................3 1.1 Classical Yao’s Garbled Circuits.............................3 Garbled Gate Generation...................................3 Garbled Gate Evaluation...................................3 From Gates to Circuits.....................................4 1.2 Optimizations to Yao’s Garbled Circuits......................4 Point and Permute........................................4 Free XOR [KS08]..........................................5 Garbled Row Reduction (GRR3) [NPS99]....................6 Garbled Row Reduction (GRR2) [PSSW09]...................6 FleXOR [KMR14].........................................7 Half Gates [ZRE15]........................................7 Garbled Gadgets [BMR16]..................................7 2 Yao’s Garbled Circuit Definitions................................9 2.1 Functionality.............................................9 2.2 Correctness...............................................9 2.3 Security..................................................9 1 Yao’s Garbled Circuits: Background 1.1 Classical Yao’s Garbled Circuits Let’s say two parties, Ginny and Evan, want to figure out
    [Show full text]
  • ASTRA: High Throughput 3PC Over Rings with Application to Secure Prediction∗
    ASTRA: High Throughput 3PC over Rings with Application to Secure Prediction∗ Harsh Chaudhari Ashish Choudhury† Indian Institute of Science, Bangalore India International Institute of Information Technology [email protected] Bangalore, India [email protected] Arpita Patra‡ Ajith Suresh Indian Institute of Science, Bangalore India Indian Institute of Science, Bangalore India [email protected] [email protected] Abstract in a way that no coalition of t parties can learn more information The concrete efficiency of secure computation has been the focus than the output (privacy) or affect the true output of the compu- of many recent works. In this work, we present concretely-efficient tation (correctness). While MPC, in general, has been a subject protocols for secure 3-party computation (3PC) over a ring of inte- of extensive research, the area of MPC with a small number of gers modulo 2` tolerating one corruption, both with semi-honest parties in the honest majority setting [4, 18, 20, 35, 56] has drawn and malicious security. Owing to the fact that computation over ring popularity of late mainly due to its efficiency and simplicity. Fur- emulates computation over the real-world system architectures, thermore, most real-time applications involve a small number of secure computation over ring has gained momentum of late. parties. Applications such as statistical and financial data analy- Cast in the offline-online paradigm, our constructions present sis [16], email-filtering [49], distributed credential encryption [56], the most efficient online phase in concrete terms. In the semi-honest Danish sugar beet auction [17] involve 3 parties.
    [Show full text]
  • Fast and Secure Three-Party Computation: the Garbled Circuit Approach
    Fast and Secure Three-party Computation: The Garbled Circuit Approach Payman Mohassel∗ Mike Rosuleky Ye Zhangz September 23, 2015 Abstract Many deployments of secure multi-party computation (MPC) in practice have used information- theoretic three-party protocols that tolerate a single, semi-honest corrupt party, since these protocols enjoy very high efficiency. We propose a new approach for secure three-party computation (3PC) that improves security while maintaining practical efficiency that is competitive with traditional information-theoretic protocols. Our protocol is based on garbled circuits and provides security against a single, malicious corrupt party. Unlike information-theoretic 3PC protocols, ours uses a constant number of rounds. Our protocol only uses inexpensive symmetric-key cryptography: hash functions, block ciphers, pseudorandom generators (in particular, no oblivious transfers) and has performance that is comparable to that of Yao's (semi- honest) 2PC protocol. We demonstrate the practicality of our protocol with an implementation based on the JustGarble framework of Bellare et al. (S&P 2013). The implementation incorporates various optimizations including the most recent techniques for efficient circuit garbling. We perform experiments on several benchmarking circuits, in different setups. Our experiments confirm that, despite providing a more demanding security guarantee, our protocol has performance comparable to existing information-theoretic 3PC. 1 Introduction Secure multi-party computation (MPC) allows a set of parties to compute a function of their joint inputs without revealing any information beyond the output of the function they compute. MPC has found nu- merous applications not only enabling various privacy-preserving tasks on sensitive data, but also removing a single point of attack by allowing for distribution of secrets and trust while maintaining the original func- tionality.
    [Show full text]
  • Banners: Binarized Neural Networks with Replicated Secret Sharing
    Banners: Binarized Neural Networks with Replicated Secret Sharing Alberto Ibarrondo Hervé Chabanne Melek Önen IDEMIA & EURECOM IDEMIA & Telecom Paris EURECOM Sophia Antipolis, France Paris, France Sophia Antipolis, France [email protected] ABSTRACT Making use of the deep learning toolbox comes at a non negligi- ble cost: one needs to acquire very large amounts of structured data, Binarized Neural Networks (BNN) provide efficient implementa- considerable computational power and vast technical expertise to tions of Convolutional Neural Networks (CNN). This makes them define and train the models. Subsequently, the expensively trained particularly suitable to perform fast and memory-light inference of deep learning models can be used to perform inference on data neural networks running on resource-constrained devices. Moti- not present during training. Naturally, risk arises when training or vated by the growing interest in CNN-based biometric recognition inference computation tasks are outsourced, following the trends on potentially insecure devices, or as part of strong multi-factor of Cloud Computing (where the model is sent to the cloud) or Edge authentication for sensitive applications, the protection of BNN Computing (where the trained model is pushed to edge devices inference on edge devices is rendered imperative. We propose a such as mobile phones or cars). In a standard setup, carrying out new method to perform secure inference of BNN relying on secure these processes on an outsourced enclave forces users to keep the multiparty computation. While preceding papers offered security model in plaintext to carry out mathematical operations, leading to in a semi-honest setting for BNN or malicious security for standard potential model theft and exposing all intermediate computations CNN, our work yields security with abort against one malicious as well as the input data and the inference result.
    [Show full text]
  • GMW Vs. Yao? Efficient Secure Two-Party Computation with Low
    GMW vs. Yao? Efficient Secure Two-Party Computation with Low Depth Circuits Thomas Schneider and Michael Zohner Engineering Cryptographic Protocols Group (ENCRYPTO), European Center for Security and Privacy by Design (EC SPRIDE), Technische Universit¨atDarmstadt, Germany fthomas.schneider,[email protected] Abstract. Secure two-party computation is a rapidly emerging field of research and enables a large variety of privacy-preserving applications such as mobile social networks or biometric identification. In the late eighties, two different approaches were proposed: Yao's garbled circuits and the protocol of Goldreich-Micali-Wigderson (GMW). Since then, re- search has mostly focused on Yao's garbled circuits as they were believed to yield better efficiency due to their constant round complexity. In this work we give several optimizations for an efficient implementa- tion of the GMW protocol. We show that for semi-honest adversaries the optimized GMW protocol can outperform today's most efficient im- plementations of Yao's garbled circuits, but highly depends on a low network latency. As a first step to overcome these latency issues, we summarize depth-optimized circuit constructions for various standard tasks. As application scenario we consider privacy-preserving face recog- nition and show that our optimized framework is up to 100 times faster than previous works even in settings with high network latency. Keywords: GMW protocol, optimizations, privacy-preserving face recognition 1 Introduction Generic secure two-party computation allows two parties to jointly compute any function on their private inputs without revealing anything but the result. Interestingly, two different approaches have been introduced at about the same time in the late eighties: Yao's garbled circuits [33] and the protocol of Goldreich- Micali-Wigderson (GMW) [11, 12].
    [Show full text]