Ouroboros Crypsinous: Privacy-Preserving Proof-of-Stake

Kerber, Thomas; Kiayias, Aggelos; Kohlweiss, Markulf; Zikas, Vassilis

doi:10.1109/sp.2019.00063

Cited by 52 publications

(33 citation statements)

References 24 publications

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“…These approaches potentially elect multiple leaders and then suggest ways to pick one leader from among the set once the set has been made public. Ganesh et al [26] and Ouroboros Crypsinous [34] extend previous proof of stake systems in the Ouroboros family [4,23,36] to consider privacy-preserving proof of stake. Algorand [29] and Fantomette [3] both introduce secret leader election protocols as part of their overall proof of stake systems as well.…”

Section: Related Workmentioning

confidence: 88%

Single Secret Leader Election

Boneh

Eskandarian

Hanzlik

et al. 2020

Proceedings of the 2nd ACM Conference on Advances in Financial Technologies

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In a Single Secret Leader Election (SSLE), a group of participants aim to randomly choose exactly one leader from the group with the restriction that the identity of the leader will be known to the chosen leader and nobody else. At a later time, the elected leader should be able to publicly reveal her identity and prove that she has won the election. The election process itself should work properly even if many registered users are passive and do not send any messages. Among the many applications of SSLEs, their potential for enabling more efficient proof-of-stake based cryptocurrencies have recently received increased attention. This paper formally defines SSLE schemes and presents three constructions that provide varying security and performance properties. First, as an existence argument, we show how to realize an ideal SSLE using indistinguishability obfuscation. Next, we show how to build SSLE from low-depth threshold fully homomorphic encryption (TFHE) via a construction which can be instantiated with a circuit of multiplicative depth as low as 10, for realistically-sized secret leader elections. Finally, we show a practical scheme relying on DDH that achieves a slightly relaxed notion of security but which boasts extremely lightweight computational requirements.

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Section: Related Workmentioning

confidence: 88%

Single Secret Leader Election

Boneh

Eskandarian

Hanzlik

et al. 2020

Proceedings of the 2nd ACM Conference on Advances in Financial Technologies

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“…Other such cryptographic commitments are also being used -e.g. in the Ouroboros Crypsinous blockchain [92].…”

Section: Confidential Transactionsmentioning

confidence: 99%

On the suitability of blockchain platforms for IoT applications: Architectures, security, privacy, and performance

et al. 2021

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Blockchain and distributed ledger technologies have received significant interest in various areas beyond the financial sector, with profound applications in the Internet of Things (IoT), providing the means for creating truly trustless and secure solutions for IoT applications. Taking into account the weak security defences that the majority of IoT devices have, it is critical that a blockchain-based solution targeting the IoT is not only capable of addressing the many challenges IoT is facing, but also does not introduce other defects, e.g. in terms of performance, making its adoption hard to achieve. This paper aims at addressing the above needs by providing a comprehensive and coherent review of the available blockchain solutions to determine their ability to meet the requirements and tackle the challenges of the IoT, using the smart home as the reference domain. Key architectural aspects of blockchain solutions, like the platforms' software and network setups, the consensus protocols used, as well as smart contracts, are examined in terms of their ability to withstand various types of common IoT and blockchain attacks, deliver enhanced privacy features, and assure adequate performance levels while processing large amounts of transactions being generated in an IoT environment. The analysis carried out identified that the defences currently provided by blockchain platforms are not su cient to thwart all the prominent attacks against blockchains, with blockchain 1.0 and 2.0 platforms being susceptible to the majority of them. On the other side, privacy related mechanisms are being supported, to varying degrees, by all platforms investigated; however, each of the them tackles specific only privacy aspects, thus rendering the overall privacy evaluation a challenging task which needs to be considered in an ad-hoc basis. If the underlying consensus protocols' performance and fault tolerance is also considered, then only a small number of platforms meet the requirements of our reference IoT domain. This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement no. 786698. The work reflects only the authors' view and the Agency is not responsible for any use that may be made of the information it contains.

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“…Cryptographic literature has seen a multitude of PoS protocols in the past years. The first provably secure PoS protocol, which initiated a family of such protocols, was Ouroboros [32], followed by Ouroboros Praos [16], Genesis [3], Crypsinous [31], and Hydra [11]. These protocols are similar to Bitcoin, in the sense that they offer eventual guarantees of liveness and persistence, and cover issues including security, privacy, and availability.…”

Section: Related Workmentioning

confidence: 99%

Account Management in Proof of Stake Ledgers

Karakostas

Kiayias

Larangeira

2020

Lecture Notes in Computer Science

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Blockchain protocols based on Proof-of-Stake (PoS) depend-by nature-on the active participation of stakeholders. If users are offline and abstain from the PoS consensus mechanism, the system's security is at risk, so it is imperative to explore ways to both maximize the level of participation and minimize the effects of non-participation. One such option is stake representation, such that users can delegate their participation rights and, in the process, form "stake pools". The core idea is that stake pool operators always participate on behalf of regular users, while the users retain the ownership of their assets. Our work provides a formal PoS wallet construction that enables delegation and stake pool formation. While investigating the construction of addresses in this setting, we distil and explore address malleability, a security property that captures the ability of an attacker to manipulate the delegation information associated with an address. Our analysis consists of identifying multiple levels of malleability, which are taken into account in our paper's core result. We then introduce the first ideal functionality of a PoS wallet's core which captures the PoS wallet's capabilities and is realized as a secure protocol based on standard cryptographic primitives. Finally, we cover how to use the wallet core in conjunction with a PoS ledger, as well as investigate how delegation and stake pools affect a PoS system's security. in the form of arbitrary attributes, which are useful for particular system operations. We identify the following desiderata for addresses in a PoS setting: Address Non-malleability: Given an address (and possibly also transactions associated with that address), it should be infeasible for an attacker to construct a different address that shares only some of its attributes, most importantly its payment key. Address Uniqueness: It should be unlikely for the address generation process to produce two equal addresses for different attributes, i.e. the addresses should be unique. Short Addresses: The addresses should be relatively short, in order to be usable and storage efficient. Multiple Types of Addresses: It should be possible to construct more than one type of addresses, with each type supporting a different subset of basic operations, e.g. to ban some addresses from staking or delegating to a stake pool. Multiple Device Support: An account should be able to exist on multiple devices that share no joint internal state. Address Recovery: An account should be able to identify its addresses, given the ledger and the payment keys which it controls. Privacy and unlinkability: Addresses should be indistinguishable and not publicly linkable to the account which manages them. An additional and equally important concern in the PoS setting is the "nothing at stake" problem [23]. As opposed to PoW, in PoS a player can easily create blocks that extend multiple parallel chains, an adversarial behavior which diverges from every PoS protocol's rules. Thus, an adversary may profit by attacking the syst...

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Ouroboros Crypsinous: Privacy-Preserving Proof-of-Stake

Cited by 52 publications

References 24 publications

Single Secret Leader Election

Single Secret Leader Election

On the suitability of blockchain platforms for IoT applications: Architectures, security, privacy, and performance

Account Management in Proof of Stake Ledgers

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