44 results sorted by ID
Possible spell-corrected query: snark
Universal SNARGs for NP from Proofs of Correctness
Zhengzhong Jin, Yael Tauman Kalai, Alex Lombardi, Surya Mathialagan
Cryptographic protocols
We give new constructions of succinct non-interactive arguments ($\mathsf{SNARG}$s) for $\mathsf{NP}$ in the settings of both non-adaptive and adaptive soundness.
Our construction of non-adaptive $\mathsf{SNARG}$ is universal assuming the security of a (leveled or unleveled) fully homomorphic encryption ($\mathsf{FHE}$) scheme as well as a batch argument ($\mathsf{BARG}$) scheme. Specifically, for any choice of parameters $\ell$ and $L$, we construct a candidate $\mathsf{SNARG}$ scheme...
Batching Adaptively-Sound SNARGs for NP
Lalita Devadas, Brent Waters, David J. Wu
Foundations
A succinct non-interactive argument (SNARG) for NP allows a prover to convince a verifier that an NP statement $x$ is true with a proof whose size is sublinear in the length of the traditional NP witness. Moreover, a SNARG is adaptively sound if the adversary can choose the statement it wants to prove after seeing the scheme parameters. Very recently, Waters and Wu (STOC 2024) showed how to construct adaptively-sound SNARGs for NP in the plain model from falsifiable assumptions...
Fully Homomorphic Encryption with Efficient Public Verification
Mi-Ying (Miryam) Huang, Baiyu Li, Xinyu Mao, Jiapeng Zhang
Public-key cryptography
We present an efficient Publicly Verifiable Fully Homomorphic Encryption scheme that, along with being able to evaluate arbitrary boolean circuits over ciphertexts, also generates a succinct proof of correct homomorphic computation. Our scheme is based on FHEW proposed by Ducas and Micciancio (Eurocrypt'15), and we incorporate the GINX homomorphic accumulator (Eurocrypt'16) for improved bootstrapping efficiency. In order to generate the proof efficiently, we generalize the widely used Rank-1...
Quantum Black-Box Separations: Succinct Non-Interactive Arguments from Falsifiable Assumptions
Gorjan Alagic, Dana Dachman-Soled, Manasi Shingane, Patrick Struck
Foundations
In their seminal work, Gentry and Wichs (STOC'11) established an impossibility result for the task of constructing an adaptively-sound SNARG via black-box reduction from a falsifiable assumption.
An exciting set of recent SNARG constructions demonstrated that, if one adopts a weaker but still quite meaningful notion of adaptive soundness, then impossibility no longer holds (Waters-Wu, Waters-Zhandry, Mathialagan-Peters-Vaikunthanathan ePrint'24). These fascinating new results raise an...
WHIR: Reed–Solomon Proximity Testing with Super-Fast Verification
Gal Arnon, Alessandro Chiesa, Giacomo Fenzi, Eylon Yogev
Cryptographic protocols
We introduce WHIR, a new IOP of proximity that offers small query complexity and exceptionally fast verification time. The WHIR verifier typically runs in a few hundred microseconds, whereas other verifiers in the literature require several milliseconds (if not much more). This significantly improves the state of the art in verifier time for hash-based SNARGs (and beyond).
Crucially, WHIR is an IOP of proximity for constrained Reed–Solomon codes, which can express a rich class of queries to...
Locally Verifiable Distributed SNARGs
Eden Aldema Tshuva, Elette Boyle, Ran Cohen, Tal Moran, Rotem Oshman
Cryptographic protocols
The field of distributed certification is concerned with certifying properties of distributed networks, where the communication topology of the network is represented as an arbitrary graph; each node of the graph is a separate processor, with its own internal state. To certify that the network satisfies a given property, a prover assigns each node of the network a certificate, and the nodes then communicate with one another and decide whether to accept or reject. We require soundness and...
What Have SNARGs Ever Done for FHE?
Michael Walter
Public-key cryptography
In recent years, there have been several constructions combining FHE with SNARGs to add integrity guarantees to FHE schemes. Most of these works focused on improving efficiency, while the precise security model with regards to client side input privacy has remained understudied. Only recently it was shown by Manulis and Nguyen (Eurocrypt'24) that this combination does not yield IND-CCA1 security. So an interesting open question is: does the SNARG actually add any meaningful security to input...
SNARGs under LWE via Propositional Proofs
Zhengzhong Jin, Yael Tauman Kalai, Alex Lombardi, Vinod Vaikuntanathan
Foundations
We construct a succinct non-interactive argument (SNARG) system for every NP language $\mathcal{L}$ that has a propositional proof of non-membership for each $x\notin \mathcal{L}$. The soundness of our SNARG system relies on the hardness of the learning with errors (LWE) problem. The common reference string (CRS) in our construction grows with the space required to verify the propositional proof, and the size of the proof grows poly-logarithmically in the length of the propositional...
A Pure Indistinguishability Obfuscation Approach to Adaptively-Sound SNARGs for NP
Brent Waters, David J. Wu
Foundations
We construct an adaptively-sound succinct non-interactive argument (SNARG) for NP in the CRS model from sub-exponentially-secure indistinguishability obfuscation ($i\mathcal{O}$) and sub-exponentially-secure one-way functions. Previously, Waters and Wu (STOC 2024), and subsequently, Waters and Zhandry (CRYPTO 2024) showed how to construct adaptively-sound SNARGs for NP by relying on sub-exponentially-secure indistinguishability obfuscation, one-way functions, and an additional algebraic...
Succinct Functional Commitments for Circuits from k-Lin
Hoeteck Wee, David J. Wu
Foundations
A functional commitment allows a user to commit to an input $\mathbf{x}$ and later, open the commitment to an arbitrary function $\mathbf{y} = f(\mathbf{x})$. The size of the commitment and the opening should be sublinear in $|\mathbf{x}|$ and $|f|$.
In this work, we give the first pairing-based functional commitment for arbitrary circuits where the size of the commitment and the size of the opening consist of a constant number of group elements. Security relies on the standard bilateral...
Fiat-Shamir for Bounded-Depth Adversaries
Liyan Chen, Yilei Chen, Zikuan Huang, Nuozhou Sun, Tianqi Yang, Yiding Zhang
Foundations
We study how to construct hash functions that can securely instantiate the Fiat-Shamir transformation against bounded-depth adversaries. The motivation is twofold. First, given the recent fruitful line of research of constructing cryptographic primitives against bounded-depth adversaries under worst-case complexity assumptions, and the rich applications of Fiat-Shamir, instantiating Fiat-Shamir hash functions against bounded-depth adversaries under worst-case complexity assumptions might...
Adaptively Sound Zero-Knowledge SNARKs for UP
Surya Mathialagan, Spencer Peters, Vinod Vaikuntanathan
We study succinct non-interactive arguments (SNARGs) and succinct non-interactive arguments of knowledge (SNARKs) for the class $\mathsf{UP}$ in the reusable designated verifier model. $\mathsf{UP}$ is an expressive subclass of $\mathsf{NP}$ consisting of all $\mathsf{NP}$ languages where each instance has at most one witness; a designated verifier SNARG (dvSNARG) is one where verification of the SNARG proof requires a private verification key; and such a dvSNARG is reusable if soundness...
Rate-1 Fully Local Somewhere Extractable Hashing from DDH
Pedro Branco, Nico Döttling, Akshayaram Srinivasan, Riccardo Zanotto
Cryptographic protocols
Somewhere statistically binding (SSB) hashing allows us to sample a special hashing key such that the digest statistically binds the input at $m$ secret locations. This hash function is said to be somewhere extractable (SE) if there is an additional trapdoor that allows the extraction of the input bits at the $m$ locations from the digest.
Devadas, Goyal, Kalai, and Vaikuntanathan (FOCS 2022) introduced a variant of somewhere extractable hashing called rate-1 fully local SE hash...
Adaptively-Sound Succinct Arguments for NP from Indistinguishability Obfuscation
Brent Waters, David J. Wu
Foundations
A succinct non-interactive argument (SNARG) for $\mathsf{NP}$ allows a prover to convince a verifier that an $\mathsf{NP}$ statement $x$ is true with a proof of size $o(|x| + |w|)$, where $w$ is the associated $\mathsf{NP}$ witness. A SNARG satisfies adaptive soundness if the malicious prover can choose the statement to prove after seeing the scheme parameters. In this work, we provide the first adaptively-sound SNARG for $\mathsf{NP}$ in the plain model assuming sub-exponentially-hard...
Holographic SNARGs for P and Batch-NP from (Polynomially Hard) Learning with Errors
Susumu Kiyoshima
Foundations
A succinct non-interactive argument (SNARG) is called holographic if the verifier runs in time sub-linear in the input length when given oracle access to an encoding of the input. We present holographic SNARGs for P and Batch-NP under the learning with errors (LWE) assumption. Our holographic SNARG for P has a verifier that runs in time $\mathsf{poly}(\lambda, \log T, \log n)$ for $T$-time computations and $n$-bit inputs ($\lambda$ is the security parameter), while our holographic SNARG for...
On Black-Box Knowledge-Sound Commit-And-Prove SNARKs
Helger Lipmaa
Cryptographic protocols
Gentry and Wichs proved that adaptively sound SNARGs for hard languages need non-falsifiable assumptions. Lipmaa and Pavlyk claimed Gentry-Wichs is tight by constructing a non-adaptively sound zk-SNARG FANA for NP from falsifiable assumptions. We show that FANA is flawed. We define and construct a fully algebraic $F$-position-binding vector commitment scheme VCF. We construct a concretely efficient commit-and-prove zk-SNARK Punic, a version of FANA with an additional VCF commitment to the...
SNARGs for Monotone Policy Batch NP
Zvika Brakerski, Maya Farber Brodsky, Yael Tauman Kalai, Alex Lombardi, Omer Paneth
Foundations
We construct a succinct non-interactive argument ($\mathsf{SNARG}$) for the class of monotone policy batch $\mathsf{NP}$ languages under the Learning with Errors ($\mathsf{LWE}$) assumption. This class is a subclass of $\mathsf{NP}$ that is associated with a monotone function~$f:\{0,1\}^k\rightarrow\{0,1\}$ and an $\mathsf{NP}$ language $\mathcal L$, and contains instances $(x_1,\ldots,x_k)$ such that $f(b_1,\ldots,b_k)=1$ where $b_j=1$ if and only if $x_j\in \mathcal L$. Our...
Non-Interactive Zero-Knowledge from Non-Interactive Batch Arguments
Jeffrey Champion, David J. Wu
Foundations
Zero-knowledge and succinctness are two important properties that arise in the study of non-interactive arguments. Previously, Kitagawa et al. (TCC 2020) showed how to obtain a non-interactive zero-knowledge (NIZK) argument for NP from a succinct non-interactive argument (SNARG) for NP. In particular, their work demonstrates how to leverage the succinctness property from an argument system and transform it into a zero-knowledge property.
In this work, we study a similar question of...
NP-Hardness of Approximating Meta-Complexity: A Cryptographic Approach
Yizhi Huang, Rahul Ilango, Hanlin Ren
Foundations
It is a long-standing open problem whether the Minimum Circuit Size Problem ($\mathrm{MCSP}$) and related meta-complexity problems are NP-complete. Even for the rare cases where the NP-hardness of meta-complexity problems are known, we only know very weak hardness of approximation.
In this work, we prove NP-hardness of approximating meta-complexity with nearly-optimal approximation gaps. Our key idea is to use *cryptographic constructions* in our reductions, where the security of the...
Certifying Giant Nonprimes
Charlotte Hoffmann, Pavel Hubáček, Chethan Kamath, Krzysztof Pietrzak
Applications
GIMPS and PrimeGrid are large-scale distributed projects dedicated to searching giant prime numbers, usually of special forms like Mersenne and Proth. The numbers in the current search-space are millions of digits large and the participating volunteers need to run resource-consuming primality tests. Once a candidate prime $N$ has been found, the only way for another party to independently verify the primality of $N$ used to be by repeating the expensive primality test. To avoid the need for...
Fully Succinct Batch Arguments for NP from Indistinguishability Obfuscation
Rachit Garg, Kristin Sheridan, Brent Waters, David J. Wu
Cryptographic protocols
Non-interactive batch arguments for $\mathsf{NP}$ provide a way to amortize the cost of $\mathsf{NP}$ verification across multiple instances. In particular, they allow a prover to convince a verifier of multiple $\mathsf{NP}$ statements with communication that scales sublinearly in the number of instances.
In this work, we study fully succinct batch arguments for $\mathsf{NP}$ in the common reference string (CRS) model where the length of the proof scales not only sublinearly in the...
LUNA: Quasi-Optimally Succinct Designated-Verifier Zero-Knowledge Arguments from Lattices
Ron Steinfeld, Amin Sakzad, Muhammed F. Esgin, Veronika Kuchta, Mert Yassi, Raymond K. Zhao
Cryptographic protocols
We introduce the first candidate Lattice-based designated verifier (DV) zero knowledge sUccinct Non-interactive Argument (ZK-SNARG) protocol, LUNA, with quasi-optimal proof length (quasi-linear in the security/privacy parameter). By simply relying on mildly stronger security assumptions, LUNA is also a candidate ZK-SNARK (i.e. argument of knowledge). LUNA achieves significant improvements in concrete proof sizes, reaching below 6 KB (compared to >32 KB in prior work) for 128-bit...
Non-Interactive Publicly-Verifiable Delegation of Committed Programs
Riddhi Ghosal, Amit Sahai, Brent Waters
Cryptographic protocols
In this work, we present the first construction of a fully non-interactive publicly-verifiable delegation scheme for committed programs. More specifically, we consider a setting where Alice is a trusted author who delegates to an untrusted worker the task of hosting a program $P$, represented as a Boolean circuit. Alice also commits to a succinct value based on $P$.
Any arbitrary user/verifier without knowledge of $P$ should be convinced that they are receiving from the worker an actual...
SNARGs and PPAD Hardness from the Decisional Diffie-Hellman Assumption
Yael Tauman Kalai, Alex Lombardi, Vinod Vaikuntanathan
Foundations
We construct succinct non-interactive arguments (SNARGs) for bounded-depth computations assuming that the decisional Diffie-Hellman (DDH) problem is sub-exponentially hard. This is the first construction of such SNARGs from a Diffie-Hellman assumption. Our SNARG is also unambiguous: for every (true) statement $x$, it is computationally hard to find any accepting proof for $x$ other than the proof produced by the prescribed prover strategy.
We obtain our result by showing how to...
Boosting Batch Arguments and RAM Delegation
Yael Tauman Kalai, Alex Lombardi, Vinod Vaikuntanathan, Daniel Wichs
Foundations
We show how to generically improve the succinctness of non-interactive publicly verifiable batch argument ($\mathsf{BARG}$) systems. In particular, we show (under a mild additional assumption) how to convert a $\mathsf{BARG}$ that generates proofs of length $\mathsf{poly} (m)\cdot k^{1-\epsilon}$, where $m$ is the length of a single instance and $k$ is the number of instances being batched, into one that generates proofs of length $\mathsf{poly} (m)\cdot \mathsf{poly} \log k$, which is the...
Impossibilities in Succinct Arguments: Black-box Extraction and More
Matteo Campanelli, Chaya Ganesh, Hamidreza Khoshakhlagh, Janno Siim
Foundations
The celebrated result by Gentry and Wichs established a theoretical barrier for succinct non-interactive arguments (SNARGs), showing that for (expressive enough) hard-on-average languages, we must assume non-falsifiable assumptions.
We further investigate those barriers by showing new negative and positive results related to the proof size.
1. We start by formalizing a folklore lower bound for the proof size of black-box extractable arguments based on the hardness of the language. This...
SNARGs for P from Sub-exponential DDH and QR
James Hulett, Ruta Jawale, Dakshita Khurana, Akshayaram Srinivasan
Cryptographic protocols
We obtain publicly verifiable Succinct Non-Interactive Arguments (SNARGs) for arbitrary deterministic computations and bounded space non-deterministic computation from standard group-based assumptions, without relying on pairings. In particular, assuming the sub-exponential hardness of both the Decisional Diffie-Hellman (DDH) and Quadratic Residuosity (QR) assumptions, we obtain the following results, where $n$ denotes the length of the instance:
1. A SNARG for any language that can be...
Batch Arguments for NP and More from Standard Bilinear Group Assumptions
Brent Waters, David J. Wu
Cryptographic protocols
Non-interactive batch arguments for NP provide a way to amortize the cost of NP verification across multiple instances. They enable a prover to convince a verifier of multiple NP statements with communication much smaller than the total witness length and verification time much smaller than individually checking each instance.
In this work, we give the first construction of a non-interactive batch argument for NP from standard assumptions on groups with bilinear maps (specifically, from...
Lower Bound on SNARGs in the Random Oracle Model
Iftach Haitner, Daniel Nukrai, Eylon Yogev
Foundations
Succinct non-interactive arguments (SNARGs) have become a fundamental primitive in the cryptographic community. The focus of this work is constructions of SNARGs in the Random Oracle Model (ROM). Such SNARGs enjoy post-quantum security and can be deployed using lightweight cryptography to heuristically instantiate the random oracle. A ROM-SNARG is \emph{$(t,\varepsilon)$-sound} if no $t$-query malicious prover can convince the verifier to accept a false statement with probability larger...
SNARGs for $\mathcal{P}$ from LWE
Arka Rai Choudhuri, Abhishek Jain, Zhengzhong Jin
Foundations
We provide the first construction of a succinct non-interactive argument (SNARG) for *all* polynomial time deterministic computations based on standard assumptions. For $T$ steps of computation, the size of the proof and the common random string (CRS) as well as the verification time are poly-logarithmic in $T$. The security of our scheme relies on the hardness of the Learning with Errors (LWE) problem against polynomial-time adversaries. Previously, SNARGs based on standard assumptions...
Somewhere Statistical Soundness, Post-Quantum Security, and SNARGs
Yael Tauman Kalai, Vinod Vaikuntanathan, Rachel Yun Zhang
Foundations
The main conceptual contribution of this paper is a unification of two leading paradigms for constructing succinct argument systems, namely Kilian's protocol and the BMW (Biehl-Meyer-Wetzel) heuristic. We define the notion of a multi-extractable somewhere statistically binding (meSSB) hash family, an extension of the notion of somewhere statistically binding hash functions (Hubacek and Wichs, ITCS 2015), and construct it from LWE. We show that when instantiating Kilian's protocol with a...
Subquadratic SNARGs in the Random Oracle Model
Alessandro Chiesa, Eylon Yogev
Foundations
In a seminal work, Micali (FOCS 1994) gave the first succinct non-interactive argument (SNARG) in the random oracle model (ROM). The construction combines a PCP and a cryptographic commitment, and has several attractive features: it is plausibly post-quantum; it can be heuristically instantiated via lightweight cryptography; and it has a transparent (public-coin) parameter setup. However, it also has a significant drawback: a large argument size.
In this work, we provide a new construction...
Tight Security Bounds for Micali’s SNARGs
Alessandro Chiesa, Eylon Yogev
Foundations
Succinct non-interactive arguments (SNARGs) in the random oracle model (ROM) have several attractive features: they are plausibly post-quantum; they can be heuristically instantiated via lightweight cryptography; and they have a transparent (public-coin) parameter setup.
The canonical construction of a SNARG in the ROM is due to Micali (FOCS 1994), who showed how to use a random oracle to compile any probabilistically checkable proof (PCP) with sufficiently-small soundness error into a...
On Succinct Arguments and Witness Encryption from Groups
Ohad Barta, Yuval Ishai, Rafail Ostrovsky, David J. Wu
Foundations
Succinct non-interactive arguments (SNARGs) enable proofs of NP statements with very low communication. Recently, there has been significant work in both theory and practice on constructing SNARGs with very short proofs. Currently, the state-of-the-art in succinctness is due to Groth (Eurocrypt 2016) who constructed a SNARG from bilinear maps where the proof consists of just 3 group elements.
In this work, we first construct a concretely-efficient designated-verifier (preprocessing) SNARG...
NIZK from SNARG
Fuyuki Kitagawa, Takahiro Matsuda, Takashi Yamakawa
Foundations
We give a construction of a non-interactive zero-knowledge (NIZK) argument for all NP languages based on a succinct non-interactive argument (SNARG) for all NP languages and a one-way function. The succinctness requirement for the SNARG is rather mild: We only require that the proof size be $|\pi|=\mathsf{poly}(\lambda)(|x|+|w|)^\delta$ for some constant $\delta<1$, where $|x|$ is the statement length, $|w|$ is the witness length, and $\lambda$ is the security parameter. Especially, we do...
Lattice-based Zero-knowledge SNARGs for Arithmetic Circuits
Anca Nitulescu
Cryptographic protocols
Succinct non-interactive arguments (SNARGs) enable verifying NP computations
with substantially lower complexity than that required
for classical NP verification. In this work, we construct a zero-knowledge
SNARG candidate that relies only on lattice-based assumptions
which are claimed to hold even in the presence of quantum computers.
Central to this new construction is the notion of linear-targeted malleability introduced
by Bitansky et al. (TCC 2013) and the conjecture that
variants of...
Succinct Arguments in the Quantum Random Oracle Model
Alessandro Chiesa, Peter Manohar, Nicholas Spooner
Foundations
Succinct non-interactive arguments (SNARGs) are highly efficient certificates of membership in non-deterministic languages. Constructions of SNARGs in the random oracle model are widely believed to be post-quantum secure, provided the oracle is instantiated with a suitable post-quantum hash function. No formal evidence, however, supports this belief.
In this work we provide the first such evidence by proving that the SNARG construction of Micali is unconditionally secure in the *quantum*...
Quasi-Optimal SNARGs via Linear Multi-Prover Interactive Proofs
Dan Boneh, Yuval Ishai, Amit Sahai, David J. Wu
Succinct non-interactive arguments (SNARGs) enable verifying NP computations with significantly less complexity than that required for classical NP verification. In this work, we focus on simultaneously minimizing the proof size and the prover complexity of SNARGs. Concretely, for a security parameter $\lambda$, we measure the asymptotic cost of achieving soundness error $2^{-\lambda}$ against provers of size $2^\lambda$. We say a SNARG is quasi-optimally succinct if its proof length is...
Lattice-Based SNARGs and Their Application to More Efficient Obfuscation
Dan Boneh, Yuval Ishai, Amit Sahai, David J. Wu
Succinct non-interactive arguments (SNARGs) enable verifying NP computations with substantially lower complexity than that required for classical NP verification. In this work, we first construct a lattice-based SNARG candidate with quasi-optimal succinctness (where the argument size is quasilinear in the security parameter). Further extension of our methods yields the first SNARG (from any assumption) that is quasi-optimal in terms of both prover overhead (polylogarithmic in the security...
Multi-Key Homomorphic Signatures Unforgeable under Insider Corruption
Russell W. F. Lai, Raymond K. H. Tai, Harry W. H. Wong, Sherman S. M. Chow
Homomorphic signatures (HS) allows the derivation of the signature of the message-function pair $(m, g)$, where $m = g(m_1, \ldots, m_K)$, given the signatures of each of the input messages $m_k$ signed under the same key. Multi-key HS (M-HS) introduced by Fiore et al. (ASIACRYPT'16) further enhances the utility by allowing evaluation of signatures under different keys. While the unforgeability of existing M-HS notions unrealistically assumes that all signers are honest, we consider the...
Succinct Randomized Encodings and their Applications
Nir Bitansky, Sanjam Garg, Sidharth Telang
Foundations
A {\em randomized encoding} allows to represent a ``complex'' function $f(x)$ by a ``simpler'' randomized function $\hat{f}(x;r)$ whose output distribution encodes $f(x)$, while revealing nothing else regarding $x$. Existing randomized encodings, geared mostly to allow encoding with low parallel complexity, have proven instrumental in various strong applications such as multiparty computation and parallel cryptography.
This work focuses on another natural complexity measure: {\em the time...
Succinct Non-Interactive Arguments via Linear Interactive Proofs
Nir Bitansky, Alessandro Chiesa, Yuval Ishai, Rafail Ostrovsky, Omer Paneth
Foundations
\emph{Succinct non-interactive arguments} (SNARGs) enable verifying NP statements with lower complexity than required for classical NP verification. Traditionally, the focus has been on minimizing the length of such arguments; nowadays researches have focused also on minimizing verification time, by drawing motivation from the problem of delegating computation.
A common relaxation is a \emph{preprocessing} SNARG, which allows the verifier to conduct an expensive offline phase that is...
Recursive Composition and Bootstrapping for SNARKs and Proof-Carrying Data
Nir Bitansky, Ran Canetti, Alessandro Chiesa, Eran Tromer
\emph{Succinct non-interactive arguments} (SNARGs) enable verifying NP statements with much lower complexity than required for classical NP verification (in fact, with complexity that is \emph{independent} of the NP language at hand). In particular, SNARGs provide strong solutions to the problem of verifiably delegating computation.
Despite recent progress in the understanding and construction of SNARGs, there remain unattained goals. First, \emph{publicly-verifiable SNARGs} are only known...
Separating Succinct Non-Interactive Arguments From All Falsifiable Assumptions
Craig Gentry, Daniel Wichs
Foundations
In this paper, we study succinct computationally sound proofs (arguments) for NP, whose communication complexity is polylogarithmic the instance and witness sizes. The seminal works of Kilian '92 and Micali '94 show that such arguments can be constructed under standard cryptographic hardness assumptions with four rounds of interaction, and that they be made non-interactive in the random-oracle model. The latter construction also gives us some evidence that succinct non interactive arguments...
We give new constructions of succinct non-interactive arguments ($\mathsf{SNARG}$s) for $\mathsf{NP}$ in the settings of both non-adaptive and adaptive soundness. Our construction of non-adaptive $\mathsf{SNARG}$ is universal assuming the security of a (leveled or unleveled) fully homomorphic encryption ($\mathsf{FHE}$) scheme as well as a batch argument ($\mathsf{BARG}$) scheme. Specifically, for any choice of parameters $\ell$ and $L$, we construct a candidate $\mathsf{SNARG}$ scheme...
A succinct non-interactive argument (SNARG) for NP allows a prover to convince a verifier that an NP statement $x$ is true with a proof whose size is sublinear in the length of the traditional NP witness. Moreover, a SNARG is adaptively sound if the adversary can choose the statement it wants to prove after seeing the scheme parameters. Very recently, Waters and Wu (STOC 2024) showed how to construct adaptively-sound SNARGs for NP in the plain model from falsifiable assumptions...
We present an efficient Publicly Verifiable Fully Homomorphic Encryption scheme that, along with being able to evaluate arbitrary boolean circuits over ciphertexts, also generates a succinct proof of correct homomorphic computation. Our scheme is based on FHEW proposed by Ducas and Micciancio (Eurocrypt'15), and we incorporate the GINX homomorphic accumulator (Eurocrypt'16) for improved bootstrapping efficiency. In order to generate the proof efficiently, we generalize the widely used Rank-1...
In their seminal work, Gentry and Wichs (STOC'11) established an impossibility result for the task of constructing an adaptively-sound SNARG via black-box reduction from a falsifiable assumption. An exciting set of recent SNARG constructions demonstrated that, if one adopts a weaker but still quite meaningful notion of adaptive soundness, then impossibility no longer holds (Waters-Wu, Waters-Zhandry, Mathialagan-Peters-Vaikunthanathan ePrint'24). These fascinating new results raise an...
We introduce WHIR, a new IOP of proximity that offers small query complexity and exceptionally fast verification time. The WHIR verifier typically runs in a few hundred microseconds, whereas other verifiers in the literature require several milliseconds (if not much more). This significantly improves the state of the art in verifier time for hash-based SNARGs (and beyond). Crucially, WHIR is an IOP of proximity for constrained Reed–Solomon codes, which can express a rich class of queries to...
The field of distributed certification is concerned with certifying properties of distributed networks, where the communication topology of the network is represented as an arbitrary graph; each node of the graph is a separate processor, with its own internal state. To certify that the network satisfies a given property, a prover assigns each node of the network a certificate, and the nodes then communicate with one another and decide whether to accept or reject. We require soundness and...
In recent years, there have been several constructions combining FHE with SNARGs to add integrity guarantees to FHE schemes. Most of these works focused on improving efficiency, while the precise security model with regards to client side input privacy has remained understudied. Only recently it was shown by Manulis and Nguyen (Eurocrypt'24) that this combination does not yield IND-CCA1 security. So an interesting open question is: does the SNARG actually add any meaningful security to input...
We construct a succinct non-interactive argument (SNARG) system for every NP language $\mathcal{L}$ that has a propositional proof of non-membership for each $x\notin \mathcal{L}$. The soundness of our SNARG system relies on the hardness of the learning with errors (LWE) problem. The common reference string (CRS) in our construction grows with the space required to verify the propositional proof, and the size of the proof grows poly-logarithmically in the length of the propositional...
We construct an adaptively-sound succinct non-interactive argument (SNARG) for NP in the CRS model from sub-exponentially-secure indistinguishability obfuscation ($i\mathcal{O}$) and sub-exponentially-secure one-way functions. Previously, Waters and Wu (STOC 2024), and subsequently, Waters and Zhandry (CRYPTO 2024) showed how to construct adaptively-sound SNARGs for NP by relying on sub-exponentially-secure indistinguishability obfuscation, one-way functions, and an additional algebraic...
A functional commitment allows a user to commit to an input $\mathbf{x}$ and later, open the commitment to an arbitrary function $\mathbf{y} = f(\mathbf{x})$. The size of the commitment and the opening should be sublinear in $|\mathbf{x}|$ and $|f|$. In this work, we give the first pairing-based functional commitment for arbitrary circuits where the size of the commitment and the size of the opening consist of a constant number of group elements. Security relies on the standard bilateral...
We study how to construct hash functions that can securely instantiate the Fiat-Shamir transformation against bounded-depth adversaries. The motivation is twofold. First, given the recent fruitful line of research of constructing cryptographic primitives against bounded-depth adversaries under worst-case complexity assumptions, and the rich applications of Fiat-Shamir, instantiating Fiat-Shamir hash functions against bounded-depth adversaries under worst-case complexity assumptions might...
We study succinct non-interactive arguments (SNARGs) and succinct non-interactive arguments of knowledge (SNARKs) for the class $\mathsf{UP}$ in the reusable designated verifier model. $\mathsf{UP}$ is an expressive subclass of $\mathsf{NP}$ consisting of all $\mathsf{NP}$ languages where each instance has at most one witness; a designated verifier SNARG (dvSNARG) is one where verification of the SNARG proof requires a private verification key; and such a dvSNARG is reusable if soundness...
Somewhere statistically binding (SSB) hashing allows us to sample a special hashing key such that the digest statistically binds the input at $m$ secret locations. This hash function is said to be somewhere extractable (SE) if there is an additional trapdoor that allows the extraction of the input bits at the $m$ locations from the digest. Devadas, Goyal, Kalai, and Vaikuntanathan (FOCS 2022) introduced a variant of somewhere extractable hashing called rate-1 fully local SE hash...
A succinct non-interactive argument (SNARG) for $\mathsf{NP}$ allows a prover to convince a verifier that an $\mathsf{NP}$ statement $x$ is true with a proof of size $o(|x| + |w|)$, where $w$ is the associated $\mathsf{NP}$ witness. A SNARG satisfies adaptive soundness if the malicious prover can choose the statement to prove after seeing the scheme parameters. In this work, we provide the first adaptively-sound SNARG for $\mathsf{NP}$ in the plain model assuming sub-exponentially-hard...
A succinct non-interactive argument (SNARG) is called holographic if the verifier runs in time sub-linear in the input length when given oracle access to an encoding of the input. We present holographic SNARGs for P and Batch-NP under the learning with errors (LWE) assumption. Our holographic SNARG for P has a verifier that runs in time $\mathsf{poly}(\lambda, \log T, \log n)$ for $T$-time computations and $n$-bit inputs ($\lambda$ is the security parameter), while our holographic SNARG for...
Gentry and Wichs proved that adaptively sound SNARGs for hard languages need non-falsifiable assumptions. Lipmaa and Pavlyk claimed Gentry-Wichs is tight by constructing a non-adaptively sound zk-SNARG FANA for NP from falsifiable assumptions. We show that FANA is flawed. We define and construct a fully algebraic $F$-position-binding vector commitment scheme VCF. We construct a concretely efficient commit-and-prove zk-SNARK Punic, a version of FANA with an additional VCF commitment to the...
We construct a succinct non-interactive argument ($\mathsf{SNARG}$) for the class of monotone policy batch $\mathsf{NP}$ languages under the Learning with Errors ($\mathsf{LWE}$) assumption. This class is a subclass of $\mathsf{NP}$ that is associated with a monotone function~$f:\{0,1\}^k\rightarrow\{0,1\}$ and an $\mathsf{NP}$ language $\mathcal L$, and contains instances $(x_1,\ldots,x_k)$ such that $f(b_1,\ldots,b_k)=1$ where $b_j=1$ if and only if $x_j\in \mathcal L$. Our...
Zero-knowledge and succinctness are two important properties that arise in the study of non-interactive arguments. Previously, Kitagawa et al. (TCC 2020) showed how to obtain a non-interactive zero-knowledge (NIZK) argument for NP from a succinct non-interactive argument (SNARG) for NP. In particular, their work demonstrates how to leverage the succinctness property from an argument system and transform it into a zero-knowledge property. In this work, we study a similar question of...
It is a long-standing open problem whether the Minimum Circuit Size Problem ($\mathrm{MCSP}$) and related meta-complexity problems are NP-complete. Even for the rare cases where the NP-hardness of meta-complexity problems are known, we only know very weak hardness of approximation. In this work, we prove NP-hardness of approximating meta-complexity with nearly-optimal approximation gaps. Our key idea is to use *cryptographic constructions* in our reductions, where the security of the...
GIMPS and PrimeGrid are large-scale distributed projects dedicated to searching giant prime numbers, usually of special forms like Mersenne and Proth. The numbers in the current search-space are millions of digits large and the participating volunteers need to run resource-consuming primality tests. Once a candidate prime $N$ has been found, the only way for another party to independently verify the primality of $N$ used to be by repeating the expensive primality test. To avoid the need for...
Non-interactive batch arguments for $\mathsf{NP}$ provide a way to amortize the cost of $\mathsf{NP}$ verification across multiple instances. In particular, they allow a prover to convince a verifier of multiple $\mathsf{NP}$ statements with communication that scales sublinearly in the number of instances. In this work, we study fully succinct batch arguments for $\mathsf{NP}$ in the common reference string (CRS) model where the length of the proof scales not only sublinearly in the...
We introduce the first candidate Lattice-based designated verifier (DV) zero knowledge sUccinct Non-interactive Argument (ZK-SNARG) protocol, LUNA, with quasi-optimal proof length (quasi-linear in the security/privacy parameter). By simply relying on mildly stronger security assumptions, LUNA is also a candidate ZK-SNARK (i.e. argument of knowledge). LUNA achieves significant improvements in concrete proof sizes, reaching below 6 KB (compared to >32 KB in prior work) for 128-bit...
In this work, we present the first construction of a fully non-interactive publicly-verifiable delegation scheme for committed programs. More specifically, we consider a setting where Alice is a trusted author who delegates to an untrusted worker the task of hosting a program $P$, represented as a Boolean circuit. Alice also commits to a succinct value based on $P$. Any arbitrary user/verifier without knowledge of $P$ should be convinced that they are receiving from the worker an actual...
We construct succinct non-interactive arguments (SNARGs) for bounded-depth computations assuming that the decisional Diffie-Hellman (DDH) problem is sub-exponentially hard. This is the first construction of such SNARGs from a Diffie-Hellman assumption. Our SNARG is also unambiguous: for every (true) statement $x$, it is computationally hard to find any accepting proof for $x$ other than the proof produced by the prescribed prover strategy. We obtain our result by showing how to...
We show how to generically improve the succinctness of non-interactive publicly verifiable batch argument ($\mathsf{BARG}$) systems. In particular, we show (under a mild additional assumption) how to convert a $\mathsf{BARG}$ that generates proofs of length $\mathsf{poly} (m)\cdot k^{1-\epsilon}$, where $m$ is the length of a single instance and $k$ is the number of instances being batched, into one that generates proofs of length $\mathsf{poly} (m)\cdot \mathsf{poly} \log k$, which is the...
The celebrated result by Gentry and Wichs established a theoretical barrier for succinct non-interactive arguments (SNARGs), showing that for (expressive enough) hard-on-average languages, we must assume non-falsifiable assumptions. We further investigate those barriers by showing new negative and positive results related to the proof size. 1. We start by formalizing a folklore lower bound for the proof size of black-box extractable arguments based on the hardness of the language. This...
We obtain publicly verifiable Succinct Non-Interactive Arguments (SNARGs) for arbitrary deterministic computations and bounded space non-deterministic computation from standard group-based assumptions, without relying on pairings. In particular, assuming the sub-exponential hardness of both the Decisional Diffie-Hellman (DDH) and Quadratic Residuosity (QR) assumptions, we obtain the following results, where $n$ denotes the length of the instance: 1. A SNARG for any language that can be...
Non-interactive batch arguments for NP provide a way to amortize the cost of NP verification across multiple instances. They enable a prover to convince a verifier of multiple NP statements with communication much smaller than the total witness length and verification time much smaller than individually checking each instance. In this work, we give the first construction of a non-interactive batch argument for NP from standard assumptions on groups with bilinear maps (specifically, from...
Succinct non-interactive arguments (SNARGs) have become a fundamental primitive in the cryptographic community. The focus of this work is constructions of SNARGs in the Random Oracle Model (ROM). Such SNARGs enjoy post-quantum security and can be deployed using lightweight cryptography to heuristically instantiate the random oracle. A ROM-SNARG is \emph{$(t,\varepsilon)$-sound} if no $t$-query malicious prover can convince the verifier to accept a false statement with probability larger...
We provide the first construction of a succinct non-interactive argument (SNARG) for *all* polynomial time deterministic computations based on standard assumptions. For $T$ steps of computation, the size of the proof and the common random string (CRS) as well as the verification time are poly-logarithmic in $T$. The security of our scheme relies on the hardness of the Learning with Errors (LWE) problem against polynomial-time adversaries. Previously, SNARGs based on standard assumptions...
The main conceptual contribution of this paper is a unification of two leading paradigms for constructing succinct argument systems, namely Kilian's protocol and the BMW (Biehl-Meyer-Wetzel) heuristic. We define the notion of a multi-extractable somewhere statistically binding (meSSB) hash family, an extension of the notion of somewhere statistically binding hash functions (Hubacek and Wichs, ITCS 2015), and construct it from LWE. We show that when instantiating Kilian's protocol with a...
In a seminal work, Micali (FOCS 1994) gave the first succinct non-interactive argument (SNARG) in the random oracle model (ROM). The construction combines a PCP and a cryptographic commitment, and has several attractive features: it is plausibly post-quantum; it can be heuristically instantiated via lightweight cryptography; and it has a transparent (public-coin) parameter setup. However, it also has a significant drawback: a large argument size. In this work, we provide a new construction...
Succinct non-interactive arguments (SNARGs) in the random oracle model (ROM) have several attractive features: they are plausibly post-quantum; they can be heuristically instantiated via lightweight cryptography; and they have a transparent (public-coin) parameter setup. The canonical construction of a SNARG in the ROM is due to Micali (FOCS 1994), who showed how to use a random oracle to compile any probabilistically checkable proof (PCP) with sufficiently-small soundness error into a...
Succinct non-interactive arguments (SNARGs) enable proofs of NP statements with very low communication. Recently, there has been significant work in both theory and practice on constructing SNARGs with very short proofs. Currently, the state-of-the-art in succinctness is due to Groth (Eurocrypt 2016) who constructed a SNARG from bilinear maps where the proof consists of just 3 group elements. In this work, we first construct a concretely-efficient designated-verifier (preprocessing) SNARG...
We give a construction of a non-interactive zero-knowledge (NIZK) argument for all NP languages based on a succinct non-interactive argument (SNARG) for all NP languages and a one-way function. The succinctness requirement for the SNARG is rather mild: We only require that the proof size be $|\pi|=\mathsf{poly}(\lambda)(|x|+|w|)^\delta$ for some constant $\delta<1$, where $|x|$ is the statement length, $|w|$ is the witness length, and $\lambda$ is the security parameter. Especially, we do...
Succinct non-interactive arguments (SNARGs) enable verifying NP computations with substantially lower complexity than that required for classical NP verification. In this work, we construct a zero-knowledge SNARG candidate that relies only on lattice-based assumptions which are claimed to hold even in the presence of quantum computers. Central to this new construction is the notion of linear-targeted malleability introduced by Bitansky et al. (TCC 2013) and the conjecture that variants of...
Succinct non-interactive arguments (SNARGs) are highly efficient certificates of membership in non-deterministic languages. Constructions of SNARGs in the random oracle model are widely believed to be post-quantum secure, provided the oracle is instantiated with a suitable post-quantum hash function. No formal evidence, however, supports this belief. In this work we provide the first such evidence by proving that the SNARG construction of Micali is unconditionally secure in the *quantum*...
Succinct non-interactive arguments (SNARGs) enable verifying NP computations with significantly less complexity than that required for classical NP verification. In this work, we focus on simultaneously minimizing the proof size and the prover complexity of SNARGs. Concretely, for a security parameter $\lambda$, we measure the asymptotic cost of achieving soundness error $2^{-\lambda}$ against provers of size $2^\lambda$. We say a SNARG is quasi-optimally succinct if its proof length is...
Succinct non-interactive arguments (SNARGs) enable verifying NP computations with substantially lower complexity than that required for classical NP verification. In this work, we first construct a lattice-based SNARG candidate with quasi-optimal succinctness (where the argument size is quasilinear in the security parameter). Further extension of our methods yields the first SNARG (from any assumption) that is quasi-optimal in terms of both prover overhead (polylogarithmic in the security...
Homomorphic signatures (HS) allows the derivation of the signature of the message-function pair $(m, g)$, where $m = g(m_1, \ldots, m_K)$, given the signatures of each of the input messages $m_k$ signed under the same key. Multi-key HS (M-HS) introduced by Fiore et al. (ASIACRYPT'16) further enhances the utility by allowing evaluation of signatures under different keys. While the unforgeability of existing M-HS notions unrealistically assumes that all signers are honest, we consider the...
A {\em randomized encoding} allows to represent a ``complex'' function $f(x)$ by a ``simpler'' randomized function $\hat{f}(x;r)$ whose output distribution encodes $f(x)$, while revealing nothing else regarding $x$. Existing randomized encodings, geared mostly to allow encoding with low parallel complexity, have proven instrumental in various strong applications such as multiparty computation and parallel cryptography. This work focuses on another natural complexity measure: {\em the time...
\emph{Succinct non-interactive arguments} (SNARGs) enable verifying NP statements with lower complexity than required for classical NP verification. Traditionally, the focus has been on minimizing the length of such arguments; nowadays researches have focused also on minimizing verification time, by drawing motivation from the problem of delegating computation. A common relaxation is a \emph{preprocessing} SNARG, which allows the verifier to conduct an expensive offline phase that is...
\emph{Succinct non-interactive arguments} (SNARGs) enable verifying NP statements with much lower complexity than required for classical NP verification (in fact, with complexity that is \emph{independent} of the NP language at hand). In particular, SNARGs provide strong solutions to the problem of verifiably delegating computation. Despite recent progress in the understanding and construction of SNARGs, there remain unattained goals. First, \emph{publicly-verifiable SNARGs} are only known...
In this paper, we study succinct computationally sound proofs (arguments) for NP, whose communication complexity is polylogarithmic the instance and witness sizes. The seminal works of Kilian '92 and Micali '94 show that such arguments can be constructed under standard cryptographic hardness assumptions with four rounds of interaction, and that they be made non-interactive in the random-oracle model. The latter construction also gives us some evidence that succinct non interactive arguments...