This Week in Blockchain Research Issue #58

Issue #58

Issue #58

Paper of the Week:

Paper Title: Everything is a Race and Nakamoto Always Wins.


  1. This work presents a new approach to the security analysis of longest chain protocols. This approach is driven by the question of whether the private attack is the worst attack for longest chain protocols in a broad sense.

  2. The adversary grows a private chain of blocks in a race to attempt to outpace the public longest chain and thereby replacing it after a block in the public chain becomes 𝑘-deep.

  3. There are three classes: 1) the original Nakamoto PoW protocol; 2) Ouroboros Praos and SnowWhite PoS protocols, 3) Chia PoSpace protocol. They all use the longest chain rule but differ in how the lotteries for proposing blocks are run.

  4. The results not only say that Chia is secure, but it is secure all the way up to the private attack threshold (although the private attack threshold is smaller for Chia than for the other two classes of protocols due to the increased power of the adversary.)

  5. That the true security threshold matches the private attack threshold in all these protocols is not a coincidence. It is due to an intimate connection between the private attack and any general attack.

  6. This approach exposes and exploits this connection by defining two key concepts: blocktree partitioning and Nakamoto blocks. Through these concepts, any attack can be viewed as a race between adversary and honest chains, not just the private attack.

AuthorsAmir Dembo*, Sreeram Kannan†, Ertem Nusret Tas*, David Tse*, Pramod Viswanath‡, Xuechao Wang‡, and Ofer Zeitouni§,

Affiliations: * Stanford University, † University of Washington, ‡ University of Illinois Urbana-Champaign, and § Weizmann Institute of Science.


1. Paper Title: LadderLeak: Breaking ECDSA With Less Than One Bit Of Nonce Leakage.

Summary: A novel class of side-channel vulnerabilities in implementations of the Montgomery ladder used in ECDSA scalar multiplication. 

Authors: Diego F. Aranha*, Felipe Rodrigues Novaes†, Akira Takahashi*‡, Mehdi Tibouchi§, and Yuval Yarom✜,

Affiliations* Aarhus University, † University of Campinas, ‡ DIGIT, § NTT Corporation, and ✜ University of Adelaide and Data61.

2. Paper Title: Custody Protocols Using Bitcoin Vaults.

Summary: This paper demonstrates how to integrate a bitcoin vault into a custody protocol and demonstrates the security properties of that protocol.

Authors: Jacob Swambo*, Spencer Hommel†, Bob McElrath , and Bryan Bishop,

Affiliations* King’s College London and † Fidelity Center for Applied Technology.


1. Paper Title: Alt-Coin Traceability.

Summary: This paper explores the extent to which Monero (XMR) and Zcash (ZEC) are virtually untraceable after the first appraisals were made about these coins.

Authors: Claire Ye*, Chinedu Ojukwu*, Anthony Hsu*, and Ruiqi Hu*,

Affiliations* Carnegie Mellon University.


1. Paper Title: Better Late than Never; Scaling Computation in Blockchains by Delaying Execution.

Summary: The first on-chain protocol to theoretically scale τ/I ≈ 1 in PoW blockchains, where (I) is the average interarrival time between blocks for validating transactions and (τ) is the validation time.

Authors: Sourav Das*, Nitin Awathare†, Ling Ren*, Vinay Joseph Ribeiro†, and Umesh Bellur†,

Affiliations* University of Illinois Urbana-Champaign and † Indian Institute of Technology Bombay.


No papers.


1. Paper Title: Expected Constant Round Byzantine Broadcast under Dishonest Majority.

Summary: This paper presents a Byzantine Broadcast protocol with amortized O(1) round complexity that works even under dishonest majority

Authors: Jun Wan*, Hanshen Xiao*, Elaine Shi‡, and Srinivas Devadas*,

Affiliations* MIT and † Cornell University.


1. Paper Title: The Digital Transformation of Payment Systems - Libra`s Impact on the Global Economy.

Summary: This master thesis examines the conceptual and technical specifications of Facebook's Libra project, which provides a comprehensive understanding of the fiat-backed digital currency, the payment system and financial infrastructures for billions of people to be launched in the first half of 2020.

AuthorsEnzo Mesanovic*,

Affiliations: * University of Basel.

2. Paper Title: The Cost of Bitcoin Mining Has Never Really Increased.

Summary: This work estimates the lower bound for the global energy cost for a period of ten years from 2010, taking into account changing oil costs, improvements in hashing technologies and hashing activity.

AuthorsYo-Der Song* and Tomaso Aste*,

Affiliations: * University College London.

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