crypto 2019 accepted papers
, for any arbitrarily small constant Purchase with a credit card, debit card, crypto, or fiat bank transfer. We further require that they are computable by a family of degree-3 polynomials over Towards that we introduce a stronger variant of $$\text {NIPoS}$$ called proof-extractable$$\text {NIPoS}$$ ($$\text {PExt-NIPoS}$$), and propose two approaches of constructing such a primitive. Using this secret sharing scheme as the main building block, we obtain the following results:Rate Preserving Non-Malleable Secret Sharing. Then for a randomly chosen s the following two distributions should be computationally indistinguishable. We propose a simple heuristic construction of $$\text {NIPoS}$$, that achieves (partial) uniqueness, based on a candidate memory-hard function in the standard model and a publicly verifiable computation with small-space verification. As an application, we show that existing lattice signatures based on Fiat-Shamir are secure without any modifications. . Accepted Papers. We present a generic study of how to build beyond birthday bound secure pseudorandom functions from public random permutations. figures. This motivates the search for other fine-grained average-case hard problems.The main goal of this paper is to identify sufficient properties for a fine-grained average-case assumption that imply cryptographic primitives such as fine-grained public key cryptography (PKC). In this setting, one of our main questions is: How small can the hint value $$\mathsf {E}(\mathsf {ek},x)$$ be? We consider the problem of Non-Interactive Two-Party Secure Computation (NISC), where Rachel wishes to publish an encryption of her input x, in such a way that any other party, who holds an input y, can send her a single message which conveys to her the value f(x, y), and nothing more. In particular, we give mild conditions under which Fiat-Shamir is secure in the quantum setting. All papers must be submitted electronically through the submission system of Latincrypt 2019 (see https://latincrypt2019.cryptojedi.org/submit.shtml). $$i\mathcal {O}$$ , where This is a public-key encryption scheme where, given an encryption of a large database D, anybody can efficiently compute an encryption of P(D) for an arbitrary RAM program P. The running time over the encrypted data should be as close as possible to the worst case running time of P, which may be sub-linear in the data size.A central difficulty in constructing a RAM-FHE scheme is hiding the sequence of memory addresses accessed by P. This is particularly problematic because an adversary may homomorphically evaluate many programs over the same ciphertext, therefore effectively “rewinding” any mechanism for making memory accesses oblivious.We identify a necessary prerequisite towards constructing RAM-FHE that we call rewindable oblivious RAM (rewindable ORAM), which provides security even in this strong adversarial setting. Considering that there exists NIZKs with efficient verifiers whose running time is strictly smaller than |C|, it is an interesting problem whether we can construct prover-efficient NIZKs. Being efficient in both aspects, our ring signature is particularly suitable for both small-scale and large-scale applications such as cryptocurrencies and e-voting systems. We obtain the first protocols with communication sublinear in the size of x, namely $$T\cdot \sqrt{|x|}$$ or $$T\cdot \root 3 \of {|x|}$$, based on DDH or, resp., pairings (and correlated-input secure hash functions). Launched on 04/04/2019 by a team based in the US, Canada, South Korea, Nigeria, and Estonia, Creditcoin aims to address the lack of credit system among the unbanked in the emerging market. Year. In the weakly-selective setting, function queries are also chosen at the beginning. When applicable, we encourage authors to include in their supplementary materials the responses to reviews from prior IACR events as described at https://iacr.org/docs/author.pdf. We introduce hardness in relative entropy, a new notion of hardness for search problems which on the one hand is satisfied by all one-way functions and on the other hand implies both next-block pseudoentropy and inaccessible entropy, two forms of computational entropy used in recent constructions of pseudorandom generators and statistically hiding commitment schemes, respectively. The computational evaluation also shows that our construction is highly likely to outperform all the relevant works in running times. Finally, we show that the CBC extractor, used by Intel’s on-chip RNG, is provably insecure in our model. First, we calculate the predicted difference distribution of Speck32/64 with one specific input difference under the Markov assumption completely for up to eight rounds and verify that this yields a globally fairly good model of the difference distribution of Speck32/64. Our first result is a construction of non-uniformly sound certificates for all $$\mathbf{NP }$$ in the random oracle model, where the attacker’s advice can depend arbitrarily on the random oracle.We next show that the existence of non-uniformly sound certificates for $$\mathbf{P }$$ (and collision resistant hash functions) yields a public-coin constant-round fully concurrent zero-knowledge argument for $$\mathbf{NP } $$. Prior work of Chattopadhyay and Li (STOC 2017) and Ball et al. . Some works consider g to be a fixed part of the group description, while others take it to be random. (CCS 2018) based on variants of the learning parity with noise (LPN) assumption over large fields. Additionally, we revisit the construction of Faust et al. For the two party case, Lindell [Lin17] recently managed to get an efficient solution which, to achieve simulation-based security, relies on an interactive, non standard, assumption on Paillier’s cryptosystem. material, and submissions are expected to be intelligible and complete without it. We revisit the concept of non-malleable secret sharing (Goyal and Kumar, STOC 2018) in the computational setting. The Fiat-Shamir transformation is a useful approach to building non-interactive arguments (of knowledge) in the random oracle model. and Pseudorandom functions are traditionally built upon block ciphers, but with the trend of permutation based cryptography, it is a natural question to investigate the design of pseudorandom functions from random permutations. Title. (TCC’18) does not achieve the desired security in a certain parameter regime, in which their algebraic security proof still holds.The correctness of statistical zeroizing attacks holds under a mild assumption on the preimage sampling algorithm with a lattice trapdoor. Specifically, our protocol has the lowest monetary cost of any known PSI protocol, when run over the Internet using cloud-based computing services (taking into account current rates for CPU + data). Is it possible to measure a physical object in a way that makes the measurement signals unintelligible to an external observer? $$\vec {s}$$ A leakage-resilient secret sharing scheme (introduced in independent works by Goyal and Kumar, STOC ’18 and Benhamouda, Degwekar, Ishai and Rabin, CRYPTO ’18) additionally requires the secrecy to hold against every unauthorized set of parties even if they obtain some bounded leakage from every other share. All authors of accepted papers will be asked to record their presentation and make it publicly available. In this work we present a collection of compilers that take secret sharing schemes for an arbitrary access structure as input and produce either leakage-resilient or non-malleable secret sharing schemes for the same access structure. Moreover, in terms of communication cost, our implementation significantly reduces both the number of rounds and the transmitted bits without exception. Prior works that designed leakage-resilient circuit compilers against $$\mathsf {AC}^0$$ leakage had to rely either on secure hardware components (Faust et al., Eurocrypt 2010, Miles-Viola, STOC 2013) or on (unproven) complexity-theoretic assumptions (Rothblum, Crypto 2012). This work attends to these vectors by focusing on two key elements: the game that codifies the scheme under attack, as well as its intended adversarial model; and the underlying interface that exposes secret key operations for use by the game. On slow networks (e.g., 10 Mbps) our protocol is actually the fastest.Our novel underlying technique is a variant of oblivious transfer (OT) extension that we call sparse OT extension. recording of the presentation as per the IACR copyright and consent form. This is the first DV-NIZK that achieves a compact proof from a standard DH type assumption. ) thresholds.In this work, we give a compiler that takes a secret sharing scheme for any monotone access structure and produces a local leakage resilient secret sharing scheme for the same access structure, with only a constant-factor asymptotic blow-up in the sizes of the shares. Using Zhandry’s PRF/PRP switching lemma we then obtain that quantum indistinguishability also holds if the internal block function is a random permutation. that DRSample provides stronger resistance to known pebbling attacks for practical values of is the maximum size of any minimal set in the access structure. We show that an almost matching upper bound of In broadcast encryption, it is possible to create ciphertexts targeted to a subset We circumvent an impossibility result for Sigma-protocols in these groups by using a short trapdoor-free CRS. with small coefficients satisfying $$\kappa $$ All submissions to Crypto 2019 are viewed as active submissions throughout the entire review . Guidelines for Authors available there as well. $$A\vec {s}=\vec {u}\bmod \,q$$ The Eurocrypt 2019 program features a lot of interesting papers. Our result is summarized below. Such proofs with degree $$k\ge 2$$ have been crucial ingredients for important privacy-preserving protocols in the discrete logarithm setting, such as Bulletproofs (IEEE S&P ’18) and arithmetic circuit arguments (EUROCRYPT ’16). We further propose a polynomial-time algorithm that can transform an arbitrary quadratic Boolean function into its disjoint quadratic form. We show how to construct rewindable ORAM using symmetric-key doubly efficient PIR (SK-DEPIR) (Canetti-Holmgren-Richelson, Boyle-Ishai-Pass-Wootters: TCC ’17). A software watermarking scheme enables users to embed a message or mark within a program while preserving its functionality. The latter primitive can be heuristically instantiated using existing indistinguishability obfuscation candidates. We do so by giving a new “compressed oracle” which allows for efficient on-the-fly simulation of random oracles, roughly analogous to the usual classical simulation. [BCS16] is particularly effective against DRSample e.g., the aAT cost is . $$\varepsilon >0$$ the communication complexity per multiplication gate is linear in the number of parties?” While a number of works have focused on reducing the communication complexity in this setting, the answer to the above question has remained elusive for over a decade.We resolve the above question in the affirmative by providing an MPC with communication complexity One of the main properties of such schemes is the supported function class of policies. As of recently, we have essentially optimal broadcast encryption (Boneh, Gentry, Waters CRYPTO ’05) under bilinear maps and traitor tracing (Goyal, Koppula, Waters STOC ’18) under LWE, where the ciphertext size is at most poly-logarithmic in N. The main contribution of our paper is to carefully combine LWE and bilinear-map based components, and get them to interact with each other, to achieve broadcast and trace. Thus, hardness in relative entropy unifies the latter two notions of computational entropy and sheds light on the apparent “duality” between them. is the multiplicative depth of the circuit. We then show that a natural and plausible average-case assumption for the key problem Zero-k-Clique from fine-grained complexity satisfies our properties. Over the past few years several increasingly stringent goals for an MHF have been proposed including the requirement that the MHF have high sequential space-time (ST) complexity, parallel space-time complexity, amortized area-time (aAT) complexity and sustained space complexity. First, we introduce one-shot proof techniques for non-linear polynomial relations of degree $$k\ge 2$$, where the protocol achieves a negligible soundness error in a single execution, and thus performs significantly better in both computation and communication compared to prior protocols requiring multiple repetitions. In this paper we generalize Lindell’s solution using hash proof systems. Our main claim is that this is indeed the case. New paper on PSI and sparse OT extension is accepted to Crypto 2019. steps with Hit enter to search with Google. $$i\mathcal {O}$$ Murphy, Murky, Mopey, Moody, and Morose decide to write a paper together over the Internet and submit it to the prestigious CRYPTO’19 conference that has the most amazing PC. Key separation is often difficult to enforce in practice. A non-interactive zero-knowledge (NIZK) protocol allows a prover to non-interactively convince a verifier of the truth of the statement without leaking any other information. Prior work of Aggarwal et al. Due to the complex dual-stream structure, the first collision attack on reduced RIPEMD-160 presented by Liu, Mendel and Wang at Asiacrypt 2017 only reaches 30 steps, having a time complexity of $$2^{70}$$. Constructions from other assumptions such as more standard pairing based assumptions, or lattice based assumptions has also proved elusive.In this work, we construct the first symmetric key attribute based encryption scheme for nondeterministic finite automata (NFA) from the learning with errors (LWE) assumption. A central challenge in the study of MPC is to balance between security guarantees, hardness assumptions, and resources required for the protocol. Moreover, we also get the best result for attacking the Inversive Congruential Generator (ICG) up to now. We obtain PCGs for multiparty correlations that can be used to make the (input-dependent) online communication of MPC protocols scale linearly with the number of parties, instead of quadratically. The shuffle model is the core idea in the Encode, Shuffle, Analyze (ESA) model introduced by Bittau et al. These techniques require only minimal cryptographic assumptions, namely, the existence of a family of collision-resistant hash functions [Kilian, STOC 1992], and achieve two remarkable properties: (i) all messages generated by the verifier are public random coins, and (ii) total verification time is merely poly-logarithmic in the time needed to naïvely execute the computation being verified [Babai et al., STOC 1991].Those early constructions were never realized in code, mostly because proving time was too large. This situation arises in scenarios where the input is partitioned or secret-shared between two or more parties, or alternatively is encoded using an additively homomorphic encryption or commitment scheme. . More precisely, we show that there are two functionally equivalent branching programs whose CVW obfuscations can be efficiently distinguished by computing the sample variance of evaluations.This statistical attack gives a new perspective on the security of the indistinguishability obfuscations: we should consider the shape of the distributions of evaluation of obfuscation to ensure security.In other words, while most of the previous (weak) security proofs have been studied with respect to algebraic attack model or ideal model, our attack shows that this algebraic security is not enough to achieve indistinguishability obfuscation. $$d>2$$ $$n=2t+1$$ Based on the newly discovered differential characteristics, we provide colliding messages pairs for the first practical collision attacks on 30 and 31 (out of 80) steps of RIPEMD-160 with time complexity $$2^{35.9}$$ and $$2^{41.5}$$ respectively. . In addition, we show that the graph construction used as a building block for the proof-of-space by Dziembowski et al. Papers from CRYPTO 2019. We show that any $$\delta _s-$$sound and $$\delta _z-$$zero-knowledge NIZK candidate satisfying $$\delta _s+\delta _z=1-\epsilon $$, for any constant $$\epsilon >0$$, can be turned into a computationally sound and zero-knowledge candidate with the only extra assumption of a subexponentially secure public-key encryption.We develop novel techniques to leverage the use of leakage simulation lemma (Jetchev-Peitzrak TCC 2014) to argue amplification. A Hardware Evaluation Study of NIST Post-Quantum Cryptographic Signature schemes. This shows that for all sizes of circuits, the O(n) overhead of all known protocols when t is maximal is inherent. . All .Our result also yields efficient, unconditional non-malleable codes that are $$\varOmega (N)$$ Ring signatures are designed to allow anyone to attach anyone else’s name to a signature, as long as the signer’s own name is also attached. Attribute-based Encryption (ABE), first introduced by [SW05, GPSW06], is a public key encryption system that can support multiple users with varying decryption permissions. $$\tilde{\mathcal {O}}(t ^2)$$ RIPEMD-160 is an ISO/IEC standard and has been applied to generate the Bitcoin address with SHA-256. In particular, if C is the size of the circuit being proved (i) the prover time is O(C) irrespective of the circuit type; (ii) the proof size and verification time are both $$O(d\log C)$$ for d-depth log-space uniform circuits (such as RAM programs). Our protocols are the first ones with communication complexities that mainly depend on the threshold parameter While these algorithms have quantum steps, the steps that impact the approximation factor A PoST allows a prover to convince a verifier that she spent a “space-time” resource (storing data—space—over a period of time). in addition, will grant permission to the IACR to distribute the presentation slides as well as an audio/video $$\varSigma $$ But what guarantee do ring signatures provide if a purported signatory wishes to denounce a signed message—or alternatively, if a signatory wishes to later come forward and claim ownership of a signature? For the honest majority case, this shows that the known optimizations via packed secret-sharing can only be obtained if one accepts that the threshold is for general circuits. $$\varOmega (N^2 \log \log N/{\text {log}} N)$$ (EUROCRYPT 2019) analyzes the differential privacy properties of the shuffle model and shows that in some cases shuffled protocols provide strictly better accuracy than local protocols. PKC 2019. $$O(N^\varepsilon )$$ Moreover, any symmetric-key proxy re-encryption scheme with reasonably strong security guarantees implies a forward and post-compromise secure ciphertext-independent updatable encryption, and hence PKE. , into a non-interactive proof in the random-oracle model. $$\vec {s}$$ for a constant c. For the honest majority case, we also show an upper bound that matches the lower bound up to a constant factor (existing upper bounds are a factor $${\mathsf {sk}}_i$$ We provide generic and black box transformations from any chosen plaintext secure Attribute-Based Encryption (ABE) or One-sided Predicate Encryption system into a chosen ciphertext secure system. Our constructions rely on a new cryptographic primitive called an extractable PRF, which may be of independent interest. Today Beam is one of the leading confidential cryptocurrencies listed on over fifty exchanges and accepted in several hunderd online stores and services.” We obtain the following main contributions:PCG foundations. Proof size and verification time of Libra are also competitive. Quantum Circuits for the CSIDH: Optimizing Quantum Evaluation of Isogenies. (EUROCRYPT–2016), and Chattopadhyay and Li (STOC–2017) provided the first explicit non-malleable codes against $$\delta $$-local tampering functions. Recently Faust et al. Policy on Irregular Submissions available at in a manner that is understandable to a general cryptographic audience. In particular the 3-XOR problem is known to require at least $$2^{\ell /3}$$ queries, and the best known algorithms require around $$2^{\ell /2}/\ell $$ operations: this roughly matches the known bounds for the 2-round Even-Mansour scheme.Using this link we describe new attacks against the 2-round Even-Mansour scheme. That is, it is consistent with some standard definitions that a non-signer might be able to repudiate a signature that he did not produce, or that this might be impossible. Not only does Libra have excellent asymptotics, but it is also efficient in practice. Formally, we define the PoST resource as a trade-off between CPU work and space-time (under reasonable cost assumptions, a rational user will prefer to use the lower-cost space-time resource over CPU work).Compared to a proof-of-work, a PoST requires less energy use, as the “difficulty” can be increased by extending the time period over which data is stored without increasing computation costs. We demand security against malicious parties. We will provide provably memory-hard constructions from all the aforementioned primitives. $$\mathrm {PFG}$$ In particular, we show that the obfuscation scheme suggested by Bartusek et al. In the CRS model, Faust et al. Waters provided the first ABE for Deterministic Finite Automata (DFA) satisfying the above properties, from a parametrized or “q-type” assumption over bilinear maps. $$n -o(\log n)$$ We also prove that any sequential pebbling (including the greedy pebbling attack) has aAT cost The security loss is $${{O}}(\log {Q_{{e}}})$$ where $${Q_{{e}}}$$ denotes the number of encryption queries. To obtain this result, we introduce a novel technique called 4-consistent tuples of sharings which we believe to be of independent interest. . $$t < n/3$$ The new O2H Theorem allows us to get better security bounds in several public-key encryption schemes. Despite their relaxed nature, we further show how our proof systems can be used as building blocks for advanced cryptographic tools such as ring signatures.Our ring signature achieves a dramatic improvement in length over all the existing proposals from lattices at the same security level. The first lattice-based construction of secret-key watermarking due to Kim and Wu (CRYPTO 2017) only ensures mark-unremovability against an adversary who does not have access to the mark-extraction oracle. Note: Online proceedings are now available! Unfortunately, they proved that constructing one using their approach would violate a popular hardness hypothesis. At the time of writing, this is the shortest SNARK with public-coin setup.2.There exists a non-interactive argument with private-coin setup, where proofs consist of 2 group elements and 3 field elements, in the generic bilinear group model. Our model is motivated by the real-world practice of outsourcing hardware production to possibly corrupted manufacturers. We conclude the paper with a comparative study of all our non-malleable code constructions with an estimation of concrete parameters. Unlike previous constructions, our protocol allows incremental difficulty adjustment, which can gracefully handle increases in the price of storage compared to CPU work. $$n \ge t$$ In terms of market action, we offered a somewhat critical view. University of Texas, Austin $$n=t+1$$ Cryptology Conference. conference Due to the current global pandemic of Covid-19, the Crypto Valley Conference on Blockchain Technology will take place in a hybrid format in 2021. We instantiate such family of graphs based on an extension of stack of localized expanders (first used by Ren and Devadas in the context of proof-of-space). Constructing Attribute Based Encryption (ABE) [56] for uniform models of computation from standard assumptions, is an important problem, about which very little is known. . No new submissions will be accepted after the abstract submission deadline (May 4th, 2019). Optimality of this protocol follows from our second contribution, a new lower bound for the accuracy of private protocols for summation of real numbers in the shuffle model. Eurocrypt is one of the three flagship conferences of the International Association for Cryptologic Research (IACR). We believe that this may be of independent interest.To achieve this result we analyze following two transformations:Parallel Repetition: We show that using parallel repetition any $$\delta _s-$$sound and $$\delta _z-$$zero-knowledge $$\mathsf {NIZK}$$ candidate can be turned into (roughly) $$\delta ^n_s-$$sound and $$1-(1-\delta _{z})^n-$$zero-knowledge candidate. For concrete parameters, it produces proofs that are around an order of magnitude smaller than those produced using Stern’s approach. For an approximate 80 bits of soundness, we highlight the following new implications:1.There exists a succinct non-interactive argument of knowledge (SNARK) with public-coin setup with proofs of size 5360 bits, under the adaptive root assumption over class groups of imaginary quadratic orders against adversaries with runtime $$2^{128}$$. Our proofs hold under the assumption that the internal function is a random function or permutation. Previous works in this direction were only qualitative: for a given amount of measurements available to an evaluation laboratory, they rated a model as “good enough” if the model assumption errors (i.e., the errors due to an incorrect choice of model family) were small with respect to the model estimation errors. Accepted Papers. Unlike previous approaches, the combination of nearly-tight proofs and efficient protocols enables the first real-world instantiations for which the parameters can be chosen in a theoretically sound manner.Our reductions have only a linear loss in the number of users, implying that our protocols are more efficient than the state of the art when instantiated with theoretically sound parameters. We also get reusable NISC in the OLE-hybrid model for general Boolean circuits using any one-way function.We complement this by a negative result, showing that reusable NISC is impossible to achieve in the OT-hybrid model. However, there is also an additional untrusted setup in which the verifier chooses a public/secret key needed to generate/verify proofs, respectively. IEEE websites place cookies on your device to give you the best user experience. We also demonstrate a birthday bound attack if either the permutations or the keys are identical. Furthermore, the resultant secret sharing scheme has optimal leakage-resilience rate, i.e., the ratio between the leakage tolerated and the size of each share can be made arbitrarily close to 1. $$d \ge 3$$ Moreover, a variant of our CRS-NIZK satisfies universal composability (UC) in the erasure-free adaptive setting. So far, the only known constructions of local leakage resilient secret sharing schemes are for threshold access structures for very low (O(1)) or very high (
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