Prism: Scaling Bitcoin by 10,000x

Yang, Liu; Wang, Xuechao; Bagaria, Vivek Kumar; Wang, Gerui; Alizadeh, Mohammad; Tse, David; Fanti, Giulia; Viswanath, Pramod

doi:10.48550/arxiv.1909.11261

Cited by 7 publications

(16 citation statements)

References 14 publications

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“…Parameters. The round interval and the network latency are set to 2 seconds according to data collected in large-scale experiments of Prism [25]. The target mining rate 𝑓 is set to 0.1 block per second per chain according to [25].…”

Section: Methodsmentioning

confidence: 99%

“…The round interval and the network latency are set to 2 seconds according to data collected in large-scale experiments of Prism [25]. The target mining rate 𝑓 is set to 0.1 block per second per chain according to [25]. The epoch length Φ is set to 2016 blocks, and the dampening filter 𝜏 is set to 4 according to Bitcoin .…”

Section: Methodsmentioning

confidence: 99%

“…We examine adversarial behavior and how it can influence the difficulties of various chains, and confirm that our scheme is secure against significant adversarial presence. The simulations are based on historical Bitcoin mining power data and parameters collected from real-world experiments of the Prism [25] parallel-chain protocol, making the insights meaningful for real-world systems. Other related works.…”

Section: Targetmentioning

confidence: 99%

“…This is a very small overhead compared to the size of the blockchain. For example, in Prism, the size of a voter (non-pivot-chain) block is 534 bytes [25]. The pivot-chain reference constitutes to an increase of 6% in communication and storage cost for voter blocks.…”

Section: Analysis Of Overheadmentioning

confidence: 99%

“…The pivot-chain reference constitutes to an increase of 6% in communication and storage cost for voter blocks. Notice that voter blocks themselves only make up for 0.21% of the size of the Prism blockchain [25], so the overhead of pivot-chain referencing is negligible, regardless of the parameters. Computation.…”

Section: Analysis Of Overheadmentioning

confidence: 99%

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Securing Parallel-chain Protocols under Variable Mining Power

Wang

Muppirala

Yang

et al. 2021

Proceedings of the 2021 ACM SIGSAC Conference on Computer and Communications Security

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Several emerging proof-of-work (PoW) blockchain protocols rely on a "parallel-chain" architecture for scaling, where instead of a single chain, multiple chains are run in parallel and aggregated. A key requirement of practical PoW blockchains is to adapt to mining power variations over time (Bitcoin's total mining power has increased by a 10 14 factor over the decade). In this paper, we consider the design of provably secure parallel-chain protocols which can adapt to such mining power variations.The Bitcoin difficulty adjustment rule adjusts the difficulty target of block mining periodically to get a constant mean inter-block time. While superficially simple, the rule has proved itself to be sophisticated and successfully secure, both in practice and in theory [11,13]. We show that natural adaptations of the Bitcoin adjustment rule to the parallel-chain case open the door to subtle, but catastrophic safety and liveness breaches. We uncover a meta-design principle that allow us to design variable mining difficulty protocols for three popular PoW blockchain proposals (Prism [3], OHIE [26], Fruitchains [21]) inside a common rubric.The principle has three components: (M1) a pivot chain, based on which blocks in all chains choose difficulty, (M2) a monotonicity condition for referencing pivot chain blocks and (M3) translating additional protocol aspects from using levels (depth) to using "difficulty levels". We show that protocols employing a subset of these principles may have catastrophic failures. The security of the designs is also proved using a common rubric -the key technical challenge involves analyzing the interaction between the pivot chain and the other chains, as well as bounding the sudden changes in difficulty target experienced in non-pivot chains. We empirically investigate the responsivity of the new mining difficulty rule via simulations based on historical Bitcoin data, and find that the protocol very effectively controls the forking rate across all the chains.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Targetmentioning

confidence: 99%

Section: Analysis Of Overheadmentioning

confidence: 99%

Section: Analysis Of Overheadmentioning

confidence: 99%

See 3 more Smart Citations

Securing Parallel-chain Protocols under Variable Mining Power

Wang

Muppirala

Yang

et al. 2021

Proceedings of the 2021 ACM SIGSAC Conference on Computer and Communications Security

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ACeD: Scalable Data Availability Oracle

Sheng

Xue

Kannan

et al. 2021

Financial Cryptography and Data Security

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A popular method in practice offloads computation and storage in blockchains by relying on committing only hashes of off-chain data into the blockchain. This mechanism is acknowledged to be vulnerable to a stalling attack: the blocks corresponding to the committed hashes may be unavailable at any honest node. The straightforward solution of broadcasting all blocks to the entire network sidesteps this data availability attack, but it is not scalable. In this work, we propose ACeD, a scalable solution to this data availability problem with O(1) communication efficiency, the first to the best of our knowledge. The key innovation is a new protocol that requires each of the N nodes to receive only O(1/N ) of the block, such that the data is guaranteed to be available in a distributed manner in the network. Our solution creatively integrates coding-theoretic designs inside of Merkle tree commitments to guarantee efficient and tamper-proof reconstruction; this solution is distinct from Asynchronous Verifiable Information Dispersal [1] (in guaranteeing efficient proofs of malformed coding) and Coded Merkle Tree [2] (which only provides guarantees for random corruption as opposed to our guarantees for worst-case corruption). We implement ACeD with full functionality in 6000 lines of Rust code, integrate the functionality as a smart contract into Ethereum via a high-performance implementation demonstrating up to 10,000 transactions per second in throughput and 6000x reduction in gas cost on the Ethereum testnet Kovan. The code is available in [3].

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Tangle 2.0 Leaderless Nakamoto Consensus on the Heaviest DAG

Müller

Penzkofer²,

Polyanskii³

et al. 2022

IEEE Access

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We introduce the theoretical foundations of the Tangle 2.0, a probabilistic leaderless consensus protocol based on a directed acyclic graph (DAG) called the Tangle. The Tangle naturally succeeds the blockchain as its next evolutionary step as it offers features suited to establish more efficient and scalable distributed ledger solutions. Consensus is no longer found in the longest chain but on the heaviest DAG, where PoW is replaced by a stake-or reputation-based weight function. The DAG structure and the underlying Reality-based UTXO Ledger allow parallel validation of transactions without the need for total ordering. Moreover, it enables the removal of the intermediary of miners and validators, allowing a pure two-step process that follows the propose-vote paradigm at the node level and not at the validator level. We propose a framework to analyse liveness and safety under different communication and adversary models. This allows providing impossibility results in some edge cases and in the asynchronous communication model. We provide formal proof of the security of the protocol assuming a common random coin.

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Prism: Scaling Bitcoin by 10,000x

Cited by 7 publications

References 14 publications

Securing Parallel-chain Protocols under Variable Mining Power

Securing Parallel-chain Protocols under Variable Mining Power

ACeD: Scalable Data Availability Oracle

Tangle 2.0 Leaderless Nakamoto Consensus on the Heaviest DAG

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