ZLiTE: Lightweight Clients for Shielded Zcash Transactions Using Trusted Execution

Wüst, Karl; Matetic, Sinisa; Schneider, Moritz; Miers, Ian; Kostiainen, Kari; Čapkun, Srđjan

doi:10.1007/978-3-030-32101-7_12

Cited by 16 publications

(8 citation statements)

References 20 publications

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“…To create ZCash transactions, the payment enclave needs to get the Merkle paths to the notes 9 that it wants to spend. We use the scheme described in [90] to keep up to date paths to all spendable notes.…”

Section: Methodsmentioning

confidence: 99%

TEEvil: Identity Lease via Trusted Execution Environments

Puddu¹,

Lain²,

Schneider³

et al. 2019

Preprint

Self Cite

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We investigate identity lease, a new type of service in which users lease their identities to third parties by providing them with full or restricted access to their online accounts or credentials. We discuss how identity lease could be abused to subvert the digital society, facilitating the spread of fake news and subverting electronic voting by enabling the sale of votes. We show that the emergence of Trusted Execution Environments and anonymous cryptocurrencies, for the first time, allows the implementation of such a lease service while guaranteeing fairness, plausible deniability and anonymity, therefore shielding the users and account renters from prosecution. To show that such a service can be practically implemented, we build an example service that we call TEEVIL leveraging Intel SGX and ZCash. Finally, we discuss defense mechanisms and challenges in the mitigation of identity lease services.

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Section: Methodsmentioning

confidence: 99%

TEEvil: Identity Lease via Trusted Execution Environments

Puddu¹,

Lain²,

Schneider³

et al. 2019

Preprint

Self Cite

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show abstract

“…While the proposed solution can utilize blockchains for implementation, blockchains can also find the design helpful [29], e.g., allowing light clients to query full nodes in a privacy-preserving way [43]. Existing solutions are either inefficient given the ever-changing nature of database [43], or require trusted hardware [38], [40], [52]. Blockchains are suitable application scenarios as they have many servers (full nodes) to achieve security and better performance, which admits more practical parameters for our design.…”

Section: A Contributionsmentioning

confidence: 99%

Relax the Non-Collusion Assumption for Multi-Server PIR

Gong¹,

Henry²,

Psomas³

et al. 2022

Preprint

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For distributed protocols involving many servers, assuming that they do not collude with each other makes some secrecy problems solvable and reduces overheads and computational hardness assumptions in others. While the non-collusion assumption is pervasive among privacy-preserving systems, it remains highly susceptible to covert, undetectable collusion among computing parties. This work stems from an observation that if the number of available computing parties is much higher than the number of parties required to perform a secure computation, collusion attempts could be deterred.We focus on the standard problem of multi-server private information retrieval (PIR) that inherently assumes that servers do not collude. For PIR application scenarios, such as those for blockchain light clients, where the available servers are plentiful, a single server's deviating action is not tremendously beneficial to itself. We can make deviations undesired through small amounts of rewards and penalties, thus raising the bar for collusion significantly. For any given multi-server 1-private PIR (i.e. the base PIR scheme is constructed assuming no pairwise collusion), we provide a collusion mitigation mechanism. We first define a two-stage sequential game that captures how rational servers interact with each other during collusion, then determine the payment rules such that the game realizes the unique sequential equilibrium: a non-collusion outcome. We also offer privacy protection for an extended period beyond the time the query executions happen, and guarantee user compensation in case of a reported privacy breach. Overall, we conjecture that the incentive structure for collusion mitigation to be functional towards relaxing the strong non-collusion assumptions across a variety of multi-party computation tasks.

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“…There are also proposals to improve the security of Ethereum light clients. One approach is to leverage Trusted Execution Enclaves (TEE) such as Intel's SGX technology, where the TEE executed code is attested as authentic, and is used to provide secure updates on the ledger state to a light client [34]- [36]. There are other mechanisms as well that can increase the security of light clients albeit at the cost of relying on a trusted party [10].…”

Section: Related Workmentioning

confidence: 99%

Adventures of a Light Blockchain Protocol in a Forest of Transactions: A Subset of a Story

2021

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The Ethereum blockchain is one of the most popular permissionless blockchains. A consequence of its popularity has been the growth of processing and data storage requirements for any node participating in the Ethereum blockchain network. For constrained devices such requirements are often infeasible to meet. To cater for such nodes, a so-called light protocol has been proposed for Ethereum where the responsibility of maintaining a correct state representation is delegated to light protocol servers. Previous research has identified dependence on external state management as a potential security vulnerability that exclusively impacts light nodes. Although a simple mitigation strategy is available, it comes at the expense of increased latency. In this work, we propose a new Ethereum node type, which we call a subset node, as an extension of the light protocol. Our proposal allows subset nodes to gain a lower latency than a pure light node with comparable or even higher security assurances by tracking and evaluating only a subset of all of the transactions issued on the blockchain. We provide a formal proof on the correctness of the blockchain state used by the subset node under the proposed model. To evaluate the practical feasibility of the subset node model, we analyze one year of historical transaction data from Ethereum, and demonstrate that a subset node tracking the state of a single account can achieve a significant reduction in storage and computational requirements when compared to a full node.

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ZLiTE: Lightweight Clients for Shielded Zcash Transactions Using Trusted Execution

Cited by 16 publications

References 20 publications

TEEvil: Identity Lease via Trusted Execution Environments

TEEvil: Identity Lease via Trusted Execution Environments

Relax the Non-Collusion Assumption for Multi-Server PIR

Adventures of a Light Blockchain Protocol in a Forest of Transactions: A Subset of a Story

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