crypto 2019 accepted papers

For instance, with $$n=64$$ and $$\lambda = 1/2$$, the memory requirement is practical, and we gain a factor 32 over brute-force search. Unfortunately, efficient distributed variants of this primitive are notoriously hard to achieve and known solutions often require expensive zero knowledge proofs to deal with malicious adversaries. TCHES has four submission deadlines per year; all papers accepted for publication in TCHES between 15 July of year n–1 and 15 July of year n will be presented at CHES of year n. Timeline. In particular, we get the first (designated-verifier) NIZK protocols for NP where following a statement-independent preprocessing, both proving and verifying are entirely “non-cryptographic” and involve only a constant computational overhead. Submissions must be anonymous, with no is the maximum size of any minimal set in the access structure. This leads to devastating attacks against OCB2’s security promises: We develop a range of very practical attacks that, amongst others, demonstrate universal forgeries and full plaintext recovery. This improves on the prior best construction of broadcast and trace under standard assumptions by Boneh and Waters (CCS ‘06), which had ciphertext size We introduce a new cryptographic primitive: Proofs of Space-Time (PoSTs) and construct an extremely simple, practical protocol for implementing these proofs. We further generalize SVC to a notion called linear map commitments (LMC), which allows one to open a committed vector to its images under linear maps with a single short message, and propose a construction over pairing groups.Equipped with these newly developed tools, we revisit the “CS proofs” paradigm [Micali, FOCS 1994] which turns any arguments with public-coin verifiers into non-interactive arguments using the Fiat-Shamir transform in the random oracle model. 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. While the latter PCGs are slower than our PCG for OT, they are still practically feasible. This paper resolves this dilemma by putting forward new notions of robustness which enable both (1) seedless PRNGs and (2) primitive-dependent adversarial sources of entropy. $$O(Cn\kappa +D_Mn^2\kappa +n^3\kappa )$$ The construction of Quach et al. MIHNP is an important class of Hidden Number Problem.In this paper, we revisit the Coppersmith technique for solving a class of modular polynomial equations, which is respectively derived from the recovering problem of the hidden number $$\alpha $$ in MIHNP. We also develop fine-grained one-way functions and hardcore bits even under these weaker assumptions.Where previous works had to assume random oracles or the existence of strong one-way functions to get a key-exchange computable in O(n) time secure against $$O(n^2)$$ adversaries (see [Merkle’78] and [BGI’08]), our assumptions seem much weaker. For instance, if we want to mark a signing algorithm, it suffices that the marked algorithm still output valid signatures (even if those signatures might be different from the ones output by the unmarked algorithm). , where n is the number of columns of A. By submitting a paper, However, it still cannot compete with the results obtained from the DLSR framework. The conference will follow the IACR Alternatively, can one learn a natural concept by using a contrived training set that makes the labeled examples useless without the line of thought that has led to their choice? (b)The first constructions of a semi-compact homomorphic encryption scheme for branching programs, where the encrypted output grows only with the program length, based on DDH or QR. , where For any function f, we give a reduction from constructing a leakage-tolerant secure multi-party computation protocol for computing f that obeys any given interaction pattern to constructing a secure (but not necessarily leakage-tolerant) protocol for a related function that obeys the star interaction pattern. In addition, we show that the graph construction used as a building block for the proof-of-space by Dziembowski et al. Thanks to our sponsors' generosity, a limited number of stipends will also be available to students unable to obtain funding to attend the conference. ECDSA is a widely adopted digital signature standard. UC San Diego continuous leakage) setting that are unconditionally secure against $$\mathsf {AC}^0$$ leakage and similar low-complexity classes.In the stateless case, we show that the original private circuits construction of Ishai, Sahai, and Wagner (Crypto 2003) is actually secure against $$\mathsf {AC}^0$$ leakage. We wish to optimize the (download) rate of such protocols, namely the asymptotic ratio between the size of the output and the sender’s message. Finally, we present the Sum of Key Alternating Ciphers (SoKAC) construction, a translation of Encrypted Davies-Meyer Dual to a public permutation based setting, and show that SoKAC achieves tight $$2n{/}3$$-bit security even when a single key is used. —the best possible bound for an iMHF. In a continuing effort to promote independent $$\vec {s}$$ for general circuits. recording of the presentation as per the IACR copyright and consent form. The solution is required to be concealed from the eyes of any algorithm running in (parallel) time less than $$\mathcal {T}$$. Compared to OPAQUE, our protocol uses only 2 flows, has comparable costs, avoids hashing onto a group, and relies on different assumptions, namely Decisional Diffie-Hellman (DDH), Strong Diffie-Hellman (SDH), and an assumption that the Boneh-Boyen function $$f_ s (x)=g^{1/( s +x)}$$ [9] is a Salted Tight One-Way Function (STOWF). This shows that for all sizes of circuits, the O(n) overhead of all known protocols when t is maximal is inherent. substantially duplicate published work or work that has been submitted in parallel to any other journal or conference/workshop This strengthening of SPHF allows for a UC (sa)PAKE design where only the client commits to its password, and only the server performs an SPHF, compared to the standard UC PAKE design paradigm where the encrypt+SPHF subroutine is used symmetrically by both parties. Year. This provides the first arithmetic analogue of the 2-message OT protocols of Peikert et al. We show that standard extractability can be upgraded to proof-extractability if the $$\text {NIPoS}$$ also has uniqueness. Our results therefore provide a general and principled path to bound the worst-case security level of an implementation. for general circuits assuming:Subexponentially secure LWEBilinear Maps In this paper, we propose the first lattice-based proof system that significantly outperforms Stern-type proofs for proving knowledge of a short In particular, each bit of the tampered codeword is set arbitrarily after adaptively reading up to d arbitrary locations within the original codeword. While key reuse can be catastrophic for security, we know of a number of cryptographic schemes for which it is provably safe. One of the main properties of such schemes is the supported function class of policies. Optionally, any amount of clearly marked supplementary material may be supplied, following the main Rolling submissions for the 2020 Symposium begin on January 1, 2019. Our transformation requires only the IND-CPA security of the original ABE scheme coupled with a pseudorandom generator (PRG) with a special security property.In particular, we consider a PRG with an n bit input $$s \in \{0,1\}^n$$ and $$n \cdot \ell $$ bit output $$y_1, \ldots , y_n$$ where each $$y_i$$ is an $$\ell $$ bit string. Similarly, if we want to mark a decryption algorithm, it suffices that the marked algorithm correctly decrypt all valid ciphertexts (but may behave differently from the unmarked algorithm on invalid or malformed ciphertexts). The leakage is said to be local if it is computed independently for each share. The iO assumption can be replaced by secure erasures. However, a major limitation of all known OT-based NISC protocols is that they are subject to selective failure attacks that allows a malicious sender to entirely compromise the security of the protocol when the receiver’s first message is reused.Motivated by the failure of the OT-based approach, we consider the problem of basing reusable NISC on parallel invocations of a standard arithmetic generalization of OT known as oblivious linear-function evaluation (OLE). Thirdly, we develop a highly selective key search policy based on a variant of Bayesian optimization which, together with our neural distinguishers, can be used to reduce the remaining security of 11-round Speck32/64 to roughly 38 bits. The PKC and TCC conferences have started issuing their own test-of-time awards, given 15 years after publication. We also provide a constant sized batch non-membership proof for a large number of elements. We provide new zero-knowledge argument of knowledge systems that work directly for a wide class of language, namely, ones involving the satisfiability of matrix-vector relations and integer relations commonly found in constructions of lattice-based cryptography. where The event’s continuing goal is to promote cybercrime research by providing an venue for university researchers to publish their work. Prepublication versions of the accepted papers from the fall submission deadline are available below. $$\tilde{\mathcal {O}}(t ^2)$$ Feb 2019. In addition, our work provides a new approach and perspective for obtaining chosen ciphertext security in the basic case of public key encryption. Together with the known results for the star interaction pattern, this gives leakage tolerant MPC for any interaction pattern with statistical/computational security. 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). The new O2H Theorem allows us to get better security bounds in several public-key encryption schemes. We construct a new iMHF candidate (DRSample+BRG) by using the bit-reversal graph to extend DRSample. In terms of market action, we offered a somewhat critical view. Although it is limited to $$\mathbf{NP }$$ relations in $$\mathbf{NC }^1$$, the proof size is $$|w| \cdot \mathsf {poly}(\kappa )$$ where w is the witness, and in particular, it matches the state-of-the-art UC-NIZK proposed by Cohen, shelat, and Wichs (CRYPTO’19) based on lattices.We construct (multi-theorem) DV-NIZKs for $$\mathbf{NP }$$ with proof size $$|C|+\mathsf {poly}(\kappa )$$ from the computational DH assumption over pairing-free groups. Moreover, a variant of our CRS-NIZK satisfies universal composability (UC) in the erasure-free adaptive setting. commitment for $$\epsilon \log \log n$$ tags (for any constant $$\epsilon >0$$) into a non-interactive non-malleable commitment w.r.t. We obtain the following main contributions:PCG foundations. In this setting, one of our main questions is: How small can the hint value $$\mathsf {E}(\mathsf {ek},x)$$ be? A. Ryan. A PoST allows a prover to convince a verifier that she spent a “space-time” resource (storing data—space—over a period of time). The first is that if the lists of accepted papers from Crypto 2018 and Crypto 2019 are compared, there are over three times the numbers of those … We study this transformation in the setting of a quantum adversary that in particular may query the random oracle in quantum superposition.Our main result is a generic reduction that transforms any quantum dishonest prover attacking the Fiat-Shamir transformation in the quantum random-oracle model into a similarly successful quantum dishonest prover attacking the underlying Prior security definitions for ring signatures do not give a conclusive answer to this question: under most existing definitions, the guarantees could go either way. $$\varOmega (N)$$ We further require that they are computable by a family of degree-3 polynomials over While some candidate proofs of replicated storage have already been proposed, their soundness relies on timing assumptions i.e., the user must reject the proof if the prover does not reply within a certain time-bound.In this paper we provide the first construction of a proof of replication which does not rely on any timing assumptions. 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. We propose two constructions under variants of the root assumption and the CDH assumption, respectively. To bypass obvious impossibility results, we make a realistic compromise by requiring that the source produce sufficient entropy even given its evaluations of the underlying primitive. Notably if $$P = NP$$, or if we live in Pessiland, then all current cryptographic assumptions will be broken. $$A\vec {s}'=\vec {u}c$$ This setting appears in the context of secure messaging platforms, verifiable outsourced computation, PIR writing, private computation of aggregate statistics, and secure multiparty computation (MPC). . 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). Accepted Papers. We then use this new technique to give the first proof of quantum indifferentiability for the Merkle-Damgård domain extender for hash functions.

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