Alejandro Ranchal-Pedrosa

Alejandro Ranchal-Pedrosa
The University of Sydney · Concurrent Systems Research Group

PhD

About

17
Publications
4,387
Reads
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159
Citations
Citations since 2017
17 Research Items
159 Citations
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Publications

Publications (17)
Preprint
Full-text available
The problem of Byzantine consensus has been key to designing secure distributed systems. However, it is particularly difficult, mainly due to the presence of Byzantine processes that act arbitrarily and the unknown message delays in general networks. Although it is well known that both safety and liveness are at risk as soon as $n/3$ Byzantine proc...
Preprint
Full-text available
Blockchain systems need to solve consensus despite the presence of rational users and failures. The notion of $(k,t)$-robustness has shown instrumental to list problems that cannot be solved if $k$ players are rational and $t$ players are Byzantine or act arbitrarily. What is less clear is whether one can solve such problems if the faults are benig...
Preprint
Full-text available
It is impossible to solve the Byzantine consensus problem in an open network of $n$ participants if only $2n/3$ or less of them are correct. As blockchains need to solve consensus, one might think that blockchains need more than $2n/3$ correct participants. But it is yet unknown whether consensus can be solved when less than $2n/3$ participants are...
Preprint
Full-text available
The long-standing impossibility of reaching agreement restricts the lifespan of blockchains. In fact, the consensus on a block to be appended to any blockchain succeeds either with some probability or at the condition that two thirds of the n replicas are not Byzantine. In the former case, the probability that the blockchain fails grows exponential...
Chapter
Full-text available
The Lightning Network (LN) is a payment network running as a second layer on top of Bitcoin and other Blockchains. This paper presents the possibility of performing a balance lockdown in the LN due to misbehaving nodes associated to a given channel. We formalize and introduce a practical attack, minimizing the economic cost of the attack. We presen...
Preprint
Full-text available
Offchain protocols aim at bypassing the scalability and privacy limitations of classic blockchains by allowing a subset of participants to execute multiple transactions outside the blockchain. While existing solutions like payment networks and factories depend on a complex routing protocol, other solutions simply require participants to build a \em...
Conference Paper
Full-text available
The Lightning Network is a second layer technology running on top of Bitcoin and other Blockchains. It is composed of a peer-to-peer network, used to transfer raw information data. Some of the links in the peer-to-peer network are identified as payment channels, used to conduct payments between two Lightning Network clients (i.e., the two nodes of...
Conference Paper
Bitcoin, the most popular blockchain system, does not scale even under very optimistic assumptions. Lightning networks, a layer on top of Bitcoin, composed of one-to-one lightning channels make it scale to up to 105 Million users. Recently, Duplex Micropayment Channel factories have been proposed based on opening multiple one-to-one payment channel...
Article
Bitcoin-like blockchains do not envisage any specific mecha- nism to avoid unfairness for the users. Hence, unfair situations, like im- possibility of cancellation of transactions or having unconfirmed trans- actions, reduce the satisfaction of users dramatically, and, as a result, they may leave the system entirely. Such a consequence would impact...
Conference Paper
Full-text available
Bitcoin-like blockchains do not envisage any specific mechanism to avoid unfairness for the users. Hence, unfair situations, like impossibility of cancellation of transactions or having unconfirmed transactions, reduce the satisfaction of users dramatically, and, as a result, they may leave the system entirely. Such a consequence would impact signi...
Chapter
Bitcoin-like blockchains do not envisage any specific mechanism to avoid unfairness for the users. Hence, unfair situations, like impossibility of cancellation of transactions explicitly or having unconfirmed transactions, reduce the satisfaction of users dramatically, and, as a result, they may leave the system entirely. Such a consequence would i...
Preprint
Full-text available
Bitcoin, the most popular blockchain system, does not scale even under very optimistic assumptions. Lightning networks, a layer on top of Bitcoin, composed of one-to-one lightning channels make it scale to up to 105 Million users. Recently, Duplex Micropayment Channel factories have been proposed based on opening multiple one-to-one payment channel...
Conference Paper
Full-text available
This paper makes the case for the use of blockchains in emerging intelligent transportation systems applications. Specifically, we argue for the use of blockchains to settle contracts and transactions in a variety of intelligent transportation scenarios. We argue that mainstream blockchains such as Ethereum have the foundations to sustain transacti...

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