This Week in Blockchain Research Issue #102

Issue #102


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Issue #102

Paper of the Week:

Paper Title: On the Anonymity Guarantees of Anonymous Proof-of-Stake Protocols.

TLDR:

  1. In proof-of-stake (PoS) blockchains, stakeholders that extend the chain are selected according to the amount of stake they own. In S&P 2019 the “Ouroboros Crypsinous” system of Kerber et al. (and concurrently Ganesh et al. in EUROCRYPT 2019) presented a mechanism that hides the identity of the stakeholder when adding blocks, hence preserving anonymity of stakeholders both during payment and mining in the Ouroboros blockchain.

  2. They focus on anonymizing the messages of the blockchain protocol, but suggest that potential identity leaks from the network-layer can be removed as well by employing anonymous broadcast channels.

  3. This work shows that this intuition is flawed. Even ideal anonymous broadcast channels do not suffice to protect the identity of the stakeholder who proposes a block.

  4. The work shows a formal network-attack against Ouroboros Crypsinous, where the adversary can leverage network delays to distinguish who is the stakeholder that added a block on the blockchain.

  5. It abstracts the above attack and shows that whenever the adversary has control over the network delay – within the synchrony bound – loss of anonymity is inherent for any protocol that provides liveness guarantees.

  6. This is done, by first proving that it is impossible to devise a (deterministic) state-machine replication protocol that achieves basic liveness guarantees and better than (1 − 2f ) anonymity at the same time (where f is the fraction of corrupted parties).

  7. Then connecting this result to the PoS setting by presenting the tagging and reverse tagging attack that allows an adversary, across several executions of the PoS protocol, to learn the stake of a target node, by simply delaying messages for the target.

  8. The paper shows that the attacks are practical, by describing how they can be carried out over the Zcash blockchain network (even when Tor is used).

  9. In conclusion, approaches are suggested that can mitigate such attacks.

AuthorsMarkulf Kohlweiss*, Varun Madathil†, Kartik Nayak‡, and Alessandra Scafuro†,

Affiliations: * University of Edinburgh, † North Carolina State University, and ‡ Duke University.


Security:

1. Paper Title: History Binding Signature.

Summary: A single private/public key pair signature scheme using verifiable random function, that binds a signer to its signature history.

Authors: Shlomi Dolev and Matan Liber,

Affiliations* Ben-Gurion University of the Negev.

2. Paper Title: Cryptocurrencies with Security Policies and Two-Factor Authentication.

Summary: New cryptographic techniques to integrate security policies (developed in the traditional banking domain) in the blockchain settings.

Authors: Florian Breuer*, Vipul Goyal†‡, and Giulio Malavolta§,

Affiliations* KIT, † NTT Research, ‡ CMU, and § MPI-SP.


Privacy:

1. Paper Title: Analysis and Probing of Parallel Channels in the Lightning Network.

Summary: While the LN has the potential to also become a privacy-preserving tool, recent work has demon- strated that the existing public payment channel network leaks private information about payments.

Authors: Alex Biryukov, Gleb Naumenko, and Sergei Tikhomirov,

Affiliations* University of Luxembourg and † thelab31.xyz.

2. Paper Title: TrustCross: Enabling Confidential Interoperability across Blockchains Using Trusted Hardware.

Summary: A privacy-preserving cross-chain platform to enable confidential interoperability across blockchains. 

Authors: Ying Lan*, Jianbo Gao*, Ke Wang*, Jiashuo Zhang*, Zhenhao Wu*, Yuesheng Zhu*, Zhong Chen*

Affiliations* Peking University.


Scalability:

No papers.


Proofs:

1. Paper Title: Latus Incentive Scheme: Enabling Decentralization in Blockchains based on Recursive SNARKs.

Summary: A novel SNARK-based construction that allows Bitcoin-like blockchains to create and communicate with sidechains of different types without knowing their internal structure.

Authors: Alberto Garoffolo*, Dmytro Kaidalov†, and Roman Oliynykov†‡,

Affiliations* Horizen , † IOHK Research, and ‡ V.N.Karazin Kharkiv National University.


Consensus:

No papers.


Tokenomics:

1. Paper Title: Categories and Functions of Crypto-Tokens.

Summary: Major issues concerning the economics of using tokens including platform finance, user adoption, stablecoins, crowdsourcing, and agency issues, with legal and regulatory implications, and finally

AuthorsLin William Cong* and Yizhou Xiao†,

Affiliations: * Cornell University and † The Chinese University of Hong Kong.

2. Paper Title: Fertile LAND: Pricing non-fungible tokens.

Summary: The pricing of parcels of virtual real estate in the largest blockchain virtual world, Decentraland; an NFT simply termed LAND.

AuthorsMichael M. Dowling*,

Affiliations: * Dublin City University Business School.

3. Paper Title: Do the Rich Get Richer? Fairness Analysis for Blockchain Incentives.

Summary: The fairness of incentives for several blockchain protocols, including PoW, ML-PoS, SL-PoS and C-PoS.

AuthorsYuming HuangJing TangQianhao CongAndrew Lim, and Jianliang Xu,

Affiliations: * National University of Singapore and † Hong Kong Baptist University.


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