A Wild Velvet Fork Appears! Inclusive Blockchain Protocol Changes in Practice

Zamyatin, Alexei; Stifter, Nicholas; Judmayer, Aljosha; Schindler, Philipp; Weippl, Edgar; Knottenbelt, William J.

doi:10.1007/978-3-662-58820-8_3

Cited by 44 publications

(41 citation statements)

References 15 publications

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“…Overlay protocols and colored coins leverage the infrastructure of existing blockchains by extending blockchains with additional features. Such protocols [8], [21], [97], are supported by most existing blockchains today, as they only require: (i) the inclusion of data in blockchain transactions and (ii) eventual agreement on their ordering [114]. As such, overlay protocols enable the creation of cryptocurrencies without bootstrapping a new dedicated blockchain.…”

Section: B Overlay Protocols Colored Coins and Tokensmentioning

confidence: 99%

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XCLAIM: Trustless, Interoperable, Cryptocurrency-Backed Assets

Zamyatin

Harz

Lind

et al. 2019

2019 IEEE Symposium on Security and Privacy (SP)

144

137

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Building trustless cross-blockchain trading protocols is challenging. Centralized exchanges thus remain the preferred route to execute transfers across blockchains. However, these services require trust and therefore undermine the very nature of the blockchains on which they operate. To overcome this, several decentralized exchanges have recently emerged which offer support for atomic cross-chain swaps (ACCS). ACCS enable the trustless exchange of cryptocurrencies across blockchains, and are the only known mechanism to do so. However, ACCS suffer significant limitations; they are slow, inefficient and costly, meaning that they are rarely used in practice.We present XCLAIM: the first generic framework for achieving trustless and efficient cross-chain exchanges using cryptocurrencybacked assets (CBAs). XCLAIM offers protocols for issuing, transferring, swapping and redeeming CBAs securely in a non-interactive manner on existing blockchains. We instantiate XCLAIM between Bitcoin and Ethereum and evaluate our implementation; it costs less than USD 0.50 to issue an arbitrary amount of Bitcoin-backed tokens on Ethereum. We show XCLAIM is not only faster, but also significantly cheaper than atomic cross-chain swaps. Finally, XCLAIM is compatible with the majority of existing blockchains without modification, and enables several novel cryptocurrency applications, such as crosschain payment channels and efficient multi-party swaps.

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Section: B Overlay Protocols Colored Coins and Tokensmentioning

confidence: 99%

“…Permanent chain splits or hard forks occur where consensus rules are loosened or conflicting rules are introduced [114], resulting in multiple instances of the same blockchain. Thereby, a mechanism to differentiate between the two resulting chains (replay protection) is necessary for secure operation [86].…”

Section: Permanent Blockchain Splitsmentioning

confidence: 99%

XCLAIM: Trustless, Interoperable, Cryptocurrency-Backed Assets

Zamyatin

Harz

Lind

et al. 2019

2019 IEEE Symposium on Security and Privacy (SP)

144

137

View full text Add to dashboard Cite

show abstract

“…Upgradability. A child sidechain can be created from a parent mainchain as a means of exploring a new feature, e.g., in the scripting language, or the consensus mechanism without requiring a soft, hard, or velvet fork [19,34]. The sidechain does not need to maintain its own separate currency, as value can be moved between the sidechain and the mainchain at will.…”

Section: Introductionmentioning

confidence: 99%

Proof-of-Stake Sidechains

Gaži¹,

Kiayias

Zindros

2019

2019 IEEE Symposium on Security and Privacy (SP)

140

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Sidechains have long been heralded as the key enabler of blockchain scalability and interoperability. However, no modeling of the concept or a provably secure construction has so far been attempted. We provide the first formal definition of what a sidechain system is and how assets can be moved between sidechains securely. We put forth a security definition that augments the known transaction ledger properties of persistence and liveness to hold across multiple ledgers and enhance them with a new "firewall" security property which safeguards each blockchain from its sidechains, limiting the impact of an otherwise catastrophic sidechain failure. We then provide a sidechain construction that is suitable for proof-of-stake (PoS) sidechain systems. As an exemplary concrete instantiation we present our construction for an epoch-based PoS system consistent with Ouroboros (Crypto 2017), the PoS blockchain protocol used in Cardano which is one of the largest pure PoS systems by market capitalisation, and we also comment how the construction can be adapted for other protocols such as Ouroboros Praos (Eurocrypt 2018), Ouroboros Genesis (CCS 2018), Snow White and Algorand. An important feature of our construction is merged-staking that prevents "goldfinger" attacks against a sidechain that is only carrying a small amount of stake. An important technique for pegging chains that we use in our construction is cross-chain certification which is facilitated by a novel cryptographic primitive we introduce called ad-hoc threshold multisignatures (ATMS) which may be of independent interest. We show how ATMS can be securely instantiated by regular and aggregate digital signatures as well as succinct arguments of knowledge such as STARKs and bulletproofs with varying degrees of storage efficiency.

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“…Forks have been discussed as early as the original Bitcoin paper (Nakamoto, 2008). They have been identified as a potential problem in security surveys (Lin and Liao, 2017) and analyzed in terms of their compatibility (Berentsen and Schär, 2017;Zamyatin et al, 2018). Additionally, there have been case study analyses for specific forks (Islam et al, 2019;Kiffer et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Blockchain Forks: A Formal Classification Framework and Persistency Analysis

Schär

2020

Singapore Econ. Rev.

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Blockchain forks can have severe economic implications, sow uncertainty and undermine trust. In this paper, we introduce a formal framework to study the emergence, persistency and economic consequences of blockchain forks. We argue that blockchain forks can be process- or protocol-based and emerge unintentionally or deliberately. We then proceed with a sub-classification of protocol-based forks and study the circumstances under which a chain split may become permanent. It can be shown that the persistency of a fork depends on the nature of the change to the consensus rules and on the relative allocation of the consensus-relevant resources. Lastly, we discuss business implications as well as potential consequences for policy makers and practitioners.

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A Wild Velvet Fork Appears! Inclusive Blockchain Protocol Changes in Practice

Cited by 44 publications

References 15 publications

XCLAIM: Trustless, Interoperable, Cryptocurrency-Backed Assets

XCLAIM: Trustless, Interoperable, Cryptocurrency-Backed Assets

Proof-of-Stake Sidechains

Blockchain Forks: A Formal Classification Framework and Persistency Analysis

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