12 research outputs found
Latus Incentive Scheme: Enabling Decentralization in Blockchains based on Recursive SNARKs
No full textIn our previous paper we introduced a novel SNARK-based construction, called Zendoo, that allows Bitcoin-like blockchains to create and communicate with sidechains of different types without knowing their internal structure. We also introduced a specific construction, called Latus, allowing creation of fully verifiable sidechains. But in there we omitted a detailed description of an incentive scheme for Latus that is an essential element of a real decentralized system. This paper fills the gap by introducing details of the incentive scheme for the Latus sidechain. Represented ideas can also be adopted by other SNARK-based blockchains to incentivize decentralized proofs creation
Darlin: Recursive Proofs using Marlin
No full textThis document describes Darlin, a succinct zero-knowledge argument of knowledge based on the Marlin SNARK (Chiesa et al., Eurocrypt 2020) and the `dlog\u27 polynomial commitment scheme from Bootle et al. EUROCRYPT 2016.
Darlin addresses recursive proofs by integrating the amortization technique from Halo (IACR eprint 2019/099) for the non-succinct parts of the dlog verifier, and we adapt their strategy for bivariate circuit encoding polynomials to aggregate Marlin\u27s inner sumchecks across the nodes the recursive scheme.
We estimate the performance impact of inner sumcheck aggregation by about 30% in a tree-like scheme of in-degree 2, and beyond when applied to linear recursion
Zendoo: a zk-SNARK Verifiable Cross-Chain Transfer Protocol Enabling Decoupled and Decentralized Sidechains
No full textSidechains are an appealing innovation devised to enable blockchain scalability and extensibility. The basic idea is simple yet powerful: construct a parallel chain - sidechain - with desired features, and provide a way to transfer coins between the mainchain and the sidechain.
In this paper, we introduce Zendoo, a construction for Bitcoin-like blockchain systems that allows the creation and communication with sidechains of different types without knowing their internal structure. We consider a parent-child relationship between the mainchain and sidechains, where sidechain nodes directly observe the mainchain while mainchain nodes only observe cryptographically authenticated certificates from sidechain maintainers. We use zk-SNARKs to construct a universal verifiable transfer mechanism that is used by sidechains.
Moreover, we propose a specific sidechain construction, named Latus, that can be built on top of this infrastructure, and realizes a decentralized verifiable blockchain system for payments. We leverage the use of recursive composition of zk-SNARKs to generate succinct proofs of sidechain state progression that are used to generate certificates’ validity proofs. This allows the mainchain to efficiently verify all operations performed in the sidechain without knowing any details about those operations
Zendoo: a zk-SNARK Verifiable Cross-Chain Transfer Protocol Enabling Decoupled and Decentralized Sidechains
No full textTrustless Cross-chain Communication for Zendoo Sidechains
No full textIn the Zendoo white paper we introduced a novel sidechain construction for Bitcoin-like blockchains, which allows a mainchain to create and communicate with sidechains of different types without knowing their internal structure. In this paper, we take a step further by introducing a comprehensive method for sidechains to communicate amongst each other. We will also discuss the details of a cross-chain token transfer protocol that extends the generic communication mechanism. With the cross-chain token transfer protocol, it can enable a broad range of new applications, such as an exchange platform, that allows the ability to trade tokens issued from different sidechains
Snarktor: A Decentralized Protocol for Scaling SNARKs Verification in Blockchains
No full textThe use of zero-knowledge Succinct Non-Interactive Arguments of Knowledge (zk-SNARK) and similar types of proofs has become increasingly popular as a solution for improving scalability, privacy, and interoperability of blockchain systems. However, even with the most advanced proving systems, verifying a single SNARK proof can require a significant amount of computational resources making it expensive to be performed on-chain. This becomes a noticeable bottleneck in scaling SNARK-based applications.
Further efficiency improvement to avoid this bottleneck lies in utilizing distributed recursive proof composition to aggregate multiple existing proofs into one that verifies all underlying proofs.
Building upon this concept, we present a new protocol for decentralized recursive proof aggregation allowing one unique proof to aggregate many input proofs to be efficiently verified on-chain, increasing the throughput and cost efficiency of SNARK-based blockchains. The protocol is designed for decentralized environments where independent actors (provers) can join and contribute to the proof generation process. We also present an incentive scheme for such actors. The protocol is abstract enough to be used with a variety of proving systems that support recursive aggregation
Probability Models of Distributed Proof Generation for zk-SNARK-Based Blockchains
No full textThe paper is devoted to the investigation of the distributed proof generation process, which makes use of recursive zk-SNARKs. Such distributed proof generation, where recursive zk-SNARK-proofs are organized in perfect Mercle trees, was for the first time proposed in Latus consensus protocol for zk-SNARKs-based sidechains. We consider two models of a such proof generation process: the simplified one, where all proofs are independent (like one level of tree), and its natural generation, where proofs are organized in partially ordered set (poset), according to tree structure. Using discrete Markov chains for modeling of corresponding proof generation process, we obtained the recurrent formulas for the expectation and variance of the number of steps needed to generate a certain number of independent proofs by a given number of provers. We asymptotically represent the expectation as a function of the one variable n/m, where n is the number of provers m is the number of proofs (leaves of tree). Using results obtained, we give numerical recommendation about the number of transactions, which should be included in the current block, idepending on the network parameters, such as time slot duration, number of provers, time needed for proof generation, etc
GIGA Protocol: Unlocking Trustless Parallel Computation in Blockchains
No full textThe scalability of modern decentralized blockchain systems is constrained by the requirement that the participating nodes execute the entire chains transactions without the ability to delegate the verification workload across multiple actors trustlessly. This is further limited by the need for sequential transaction execution and repeated block validation, where each node must re-execute all transactions before accepting blocks, also leading to delayed broadcasting in many architectures.
Consequently, throughput is limited by the capacity of individual nodes, significantly preventing scalability.
In this paper, we introduce GIGA, a SNARK-based protocol that enables trustless parallel execution of transactions, processing non-conflicting operations concurrently, while preserving security guarantees and state consistency. The protocol organizes transactions into non-conflicting batches which are executed and proven in parallel, distributing execution across multiple decentralized entities. These batch proofs are recursively aggregated into a single succinct proof that validates the entire block.
As a result, the protocol both distributes the execution workload and removes redundant re-execution from the network, significantly improving blockchain throughput while not affecting decentralization.
Performance estimates demonstrate that, under the same system assumptions (e.g., consensus, networking, and virtual machine architecture) and under high degrees of transaction parallelism (i.e., when most transactions operate on disjoint parts of the state), our protocol may achieve over a 10000x throughput improvement compared to popular blockchain architectures that use sequential execution models, and over a 500x improvement compared to blockchain architectures employing intra-node parallelization schemes.
Furthermore, our protocol enables a significant increase in transaction computational complexity, unlocking a wide range of use cases that were previously unfeasible on traditional blockchain architectures due to the limited on-chain computational capacity.
Additionally, we propose a reward mechanism that ensures the economic sustainability of the proving network, dynamically adjusting to computational demand while fostering competition among provers based on cost-efficiency and reliability
SNhunt151: An explosive event inside a dense cocoon
No full textIndexación ScopusSNhunt151 was initially classified as a supernova (SN) impostor (nonterminal outburst of a massive star). It exhibited a slow increase in luminosity, lasting about 450 d, followed by a major brightening that reaches MV ≈ -18 mag. No source is detected to MV ≳ -13 mag in archival images at the position of SNhunt151 before the slow rise. Low-to-mid-resolution optical spectra obtained during the pronounced brightening show very little evolution, being dominated at all times by multicomponent Balmer emission lines, a signature of interaction between the material ejected in the new outburst and the pre-existing circumstellar medium. We also analysed mid-infrared images from the Spitzer Space Telescope, detecting a source at the transient position in 2014 and 2015. Overall, SNhunt151 is spectroscopically a Type IIn SN, somewhat similar to SN 2009ip. However, there are also some differences, such as a slow pre-discovery rise, a relatively broad light-curve peak showing a longer rise time (~50 d), and a slower decline, along with a negligible change in the temperature around the peak (T ≤ 104 K). We suggest that SNhunt151 is the result of an outburst, or an SN explosion, within a dense circumstellar nebula, similar to those embedding some luminous blue variables like η Carinae and originating from past mass-loss events. © 2017 The Author(s).https://authors.library.caltech.edu/85510/1/sty009.pd
Digital PCR for high sensitivity viral detection in false-negative SARS-CoV-2 patients
No full textAbstract Patients requiring diagnostic testing for coronavirus disease 2019 (COVID-19) are routinely assessed by reverse-transcription quantitative polymerase chain reaction (RT-qPCR) amplification of Sars-CoV-2 virus RNA extracted from oro/nasopharyngeal swabs. Despite the good specificity of the assays certified for SARS-CoV-2 molecular detection, and a theoretical sensitivity of few viral gene copies per reaction, a relatively high rate of false negatives continues to be reported. This is an important challenge in the management of patients on hospital admission and for correct monitoring of the infectivity after the acute phase. In the present report, we show that the use of digital PCR, a high sensitivity method to detect low amplicon numbers, allowed us to correctly detecting infection in swab material in a significant number of false negatives. We show that the implementation of digital PCR methods in the diagnostic assessment of COVID-19 could resolve, at least in part, this timely issue
