Lukas Aumayr

Projektass.(FWF) Dipl.-Ing. Dr.techn. / BSc

Lukas Aumayr

Blockchain, Applied Cryptography, Security, Privacy, Cryptanalysis, Distributed protocols

Roles
  • PostDoc Researcher
Publications (created while at TU Wien)
    2024
    • Foundations of Bitcoin-Compatible Scalability Protocols
      Aumayr, L. (2024). Foundations of Bitcoin-Compatible Scalability Protocols [Dissertation, Technische Universität Wien]. reposiTUm.
      DOI: 10.34726/hss.2024.122127 Metadata
      Abstract
      Permissionless blockchains allow mutually untrusted users to transfer money in a decentralized way. Unfortunately, these blockchains face a scalability problem, which means they are technically limited to processing only a relatively small number of transactions compared to traditional, centralized systems. Payment Channel Networks (PCNs) are among the most prominent solutions to mitigate these scalability issues.The basic idea of PCNs is to outsource transactions to so-called payment channels between two users and then link these channels to form a network where any two users connected by a path of channels can perform transactions. The advantage is that only the transactions for opening and closing these channels need to go on the blockchain, while any other transaction happens outside of the blockchain, thus increasing the overall transaction throughput. Several different PCN protocols exist and are used in practice (e.g., the Lightning Network with a value of approximately 150M USD). However, even these have their sets of issues. In this thesis, we investigate existing PCN protocols and identify issues in terms of security, privacy, efficiency, and limited functionality. Simultaneously, we introduce new protocols that overcome these issues and improve the state of the art. We focus on Bitcoin-compatible solutions since Bitcoin is not only the largest cryptocurrency in terms of market capitalization but also has a limited set of scripting capabilities, thus making our protocols compatible with a large number of other cryptocurrencies as well. We also conduct a rigorous formal security analysis of our protocols. More concretely, this thesis makes the following contributions. First, we introduce Sleepy Channels, enabling secure payment channels even when users are not continuously online. This is a significant shift from existing constructions where going offline puts users' funds at risk. Further, we generalize the notion of payment channels (Generalized Channels) and make them support any application that the underlying blockchain supports rather than only payments. Second, we introduce a new construction (Blitz) that achieves secure payments across a path of multiple channels in PCNs while reducing the number of interactions for each intermediary to a single one (from two or more) and takes only constant time instead of linear in the path length. We also provide the first secure construction for atomically updating multiple channels that are not on a path (Thora). Finally, we provide the first Bitcoin-Compatible Virtual Channel construction. These virtual channels allow two users to open a direct channel via one intermediary without putting an opening or closing transaction on the blockchain. We further analyze other existing virtual channel constructions, identify a novel attack, and introduce secure and efficient virtual channels over multiple intermediaries (Donner).These contributions interplay seamlessly. Collectively, they offer a versatile, ad-hoc solution connecting any two users securely without an on-chain footprint for applications that go beyond payments. Thus, this thesis aims to reshape the understanding of PCNs and give more general and efficient solutions to the scalability problem.
    2023
    • Breaking and Fixing Virtual Channels: Domino Attack and Donner
      Aumayr, L., Moreno-Sanchez, P., Kate, A., & Maffei, M. (2023). Breaking and Fixing Virtual Channels: Domino Attack and Donner. In Proceedings Network and Distributed System Security Symposium 2023. 30th Annual Network and Distributed System Security Symposium (NDSS) 2023, San Diego, United States of America (the).
      DOI: 10.14722/ndss.2023.24370 Metadata
      Abstract
      Payment channel networks (PCNs) mitigate the scalability issues of current decentralized cryptocurrencies. They allow for arbitrarily many payments between users connected through a path of intermediate payment channels, while requiring interacting with the blockchain only to open and close the channels. Unfortunately, PCNs are (i) tailored to payments, excluding more complex smart contract functionalities, such as the oracle-enabling Discreet Log Contracts and (ii) their need for active participation from intermediaries may make payments unreliable, slower, expensive, and privacy-invasive. Virtual channels are among the most promising techniques to mitigate these issues, allowing two endpoints of a path to create a direct channel over the intermediaries without any interaction with the blockchain. After such a virtual channel is constructed, (i) the endpoints can use this direct channel for applications other than payments and (ii) the intermediaries are no longer involved in updates. In this work, we first introduce the Domino attack, a new DoS/griefing style attack that leverages virtual channels to destruct the PCN itself and is inherent to the design adopted by the existing Bitcoin-compatible virtual channels. We then demonstrate its severity by a quantitative analysis on a snapshot of the Lightning Network (LN), the most widely deployed PCN at present. We finally discuss other serious drawbacks of existing virtual channel designs, such as the support for only a single intermediary, a latency and blockchain overhead linear in the path length, or a non-constant storage overhead per user. We then present Donner, the first virtual channel construction that overcomes the shortcomings above, by relying on a novel design paradigm. We formally define and prove security and privacy properties in the Universal Composability framework. Our evaluation shows that Donner is efficient, reduces the on-chain number of transactions for disputes from linear in the path length to a single one, which is the key to prevent Domino attacks, and reduces the storage overhead from logarithmic in the path length to constant. Donner is Bitcoin-compatible and can be easily integrated in the LN.
    • Glimpse: On-Demand PoW Light Client with Constant-Size Storage for DeFi
      Scaffino, G., Aumayr, L., Avarikioti, G., & Maffei, M. (2023). Glimpse: On-Demand PoW Light Client with Constant-Size Storage for DeFi. In Proceedings of the 32nd USENIX Security Symposium (pp. 733–750).
      Metadata
      Abstract
      Cross-chain communication is instrumental in unleashing the full potential of blockchain technologies, as it allows users and developers to exploit the unique design features and the profit opportunities of different existing blockchains. The majority of interoperability solutions are provided by centralized exchanges and bridge protocols based on a trusted majority, both introducing undesirable trust assumptions compared to native blockchain assets. Hence, increasing attention has been given to decentralized solutions: Light and super-light clients paved the way for chain relays, which allow verifying on a blockchain the state of another blockchain by respectively verifying and storing a linear and logarithmic amount of data. Unfortunately, relays turn out to be inefficient in terms of computational costs, storage, or compatibility. We introduce Glimpse, an on-demand bridge that leverages a novel on-demand light client construction with only constant on-chain storage, cost, and computational overhead. Glimpse is expressive, enabling a plethora of DeFi and off-chain applications such as lending, pegs, proofs of oracle attestations, and betting hubs. Glimpse also remains compatible with blockchains featuring a limited scripting language such as the Liquid Network (a pegged sidechain of Bitcoin), for which we present a concrete instantiation. We prove Glimpse security in the Universal Composability (UC) framework and further conduct an economic analysis. We evaluate the cost of Glimpse for Bitcoin-like chains: verifying a simple transaction has at most 700 bytes of on-chain overhead, resulting in a one-time fee of $3, only twice as much as a standard Bitcoin transaction.
    2022
    • Sleepy Channels: Bi-directional Payment Channels without Watchtowers
      Aumayr, L., Thyagarajan, S. A., Malavolta, G., Moreno-Sanchez, P., & Maffei, M. (2022). Sleepy Channels: Bi-directional Payment Channels without Watchtowers. In CCS ’22: Proceedings of the 2022 ACM SIGSAC Conference on Computer and Communications Security (pp. 179–192). Association for Computing Machinery.
      DOI: 10.1145/3548606.3559370 Metadata
      Abstract
      Payment channels (PC) are a promising solution to the scalability issue of cryptocurrencies, allowing users to perform the bulk of the transactions off-chain without needing to post everything on the blockchain. Many PC proposals however, suffer from a severe limitation: Both parties need to constantly monitor the blockchain to ensure that the other party did not post an outdated transaction. If this event happens, the honest party needs to react promptly and engage in a punishment procedure. This means that prolonged absence periods (e.g., a power outage) may be exploited by malicious users. As a mitigation, the community has introduced watchtowers, a third-party monitoring the blockchain on behalf of off-line users. Unfortunately, watchtowers are either trusted, which is critical from a security perspective, or they have to lock a certain amount of coins, called collateral, for each monitored PC in order to be held accountable, which is financially infeasible for a large network. We present Sleepy Channels, the first bi-directional PC protocol without watchtowers (or any other third party) that supports an unbounded number of payments and does not require parties to be persistently online. The key idea is to confine the period in which PC updates can be validated on-chain to a short, pre-determined time window, which is when the PC parties have to be online. This behavior is incentivized by letting the parties lock a collateral in the PC, which can be adjusted depending on their mutual trust and which they get back much sooner if they are online during this time window. Our protocol is compatible with any blockchain that is capable of verifying digital signatures (e.g., Bitcoin), as shown by our proof of concept. Moreover, our experimental results show that Sleepy Channels impose a communication and computation overhead similar to state-of-the-art PC protocols while removing watchtower's collateral and fees for the monitoring service.
    • Thora: Atomic and Privacy-Preserving Multi-Channel Updates
      Aumayr, L., Abbaszadeh, K., & Maffei, M. (2022). Thora: Atomic and Privacy-Preserving Multi-Channel Updates. In CCS ’22: Proceedings of the 2022 ACM SIGSAC Conference on Computer and Communications Security (pp. 165–178). Association for Computing Machinery.
      DOI: 10.1145/3548606.3560556 Metadata
      Abstract
      Most blockchain-based cryptocurrencies suffer from a heavily limited transaction throughput, which is a barrier to their growing adoption. Payment channel networks (PCNs) are one of the promising solutions to this problem. PCNs reduce the on-chain load of transactions and increase the throughput by processing many payments off-chain. In fact, any two users connected via a path of payment channels (i.e., joint addresses between the two channel end-points) can perform payments, and the underlying blockchain is used only when there is a dispute between users. Unfortunately, payments in PCNs can only be conducted securely along a path, which prevents the design of many interesting applications. Moreover, the most widely used implementation, the Lightning Network in Bitcoin, suffers from a collateral lock time linear in the path length, it is affected by security issues, and it relies on specific scripting features called Hash Timelock Contracts that hinders the applicability of the underlying protocol in other blockchains. In this work, we present Thora, the first Bitcoin-compatible off-chain protocol that enables the atomic update of arbitrary channels (i.e., not necessarily forming a path). This enables the design of a number of new off-chain applications, such as payments across different PCNs sharing the same blockchain, secure and trustless crowdfunding, and channel rebalancing. Our construction requires no specific scripting functionalities other than digital signatures and timelocks, thereby being applicable to a wider range of blockchains. We formally define security and privacy in the Universal Composability framework and show that our cryptographic protocol is a realization thereof. In our performance evaluation, we show that our construction requires only constant collateral, independently from the number of channels, and has only a moderate off-chain communication as well as computation overhead.
    2021
    • Blitz: Secure Multi-Hop Payments Without Two-Phase Commits
      Aumayr, L., Moreno-Sanchez, P., Kate, A., & Maffei, M. (2021). Blitz: Secure Multi-Hop Payments Without Two-Phase Commits. In 30th USENIX Security Symposium (pp. 4043–4060). USENIX: The Advanced Computing Systems Association.
      Metadata ⯈Fulltext (preprint)
      Abstract
      Payment-channel networks (PCN) are the most prominent approach to tackle the scalability issues of current permissionless blockchains. A PCN reduces the load on-chain by allowing arbitrarily many off-chain multi-hop payments (MHPs) between any two users connected through a path of payment channels. Unfortunately, current MHP protocols are far from satisfactory. One-round MHPs (e.g., Interledger) are insecure as a malicious intermediary can steal the payment funds. Two-round MHPs (e.g., Lightning Network (LN)) follow the 2-phase-commit paradigm as in databases to overcome this issue. However, when tied with economical incentives, 2-phase-commit brings other security threats (i.e., wormhole attacks), staggered collateral (i.e., funds are locked for a time proportional to the payment path length) and dependency on specific scripting language functionality (e.g., Hash Time-Lock Contracts) that hinders a wider deployment in practice. We present Blitz, a novel MHP protocol that demonstrates for the first time that we can achieve the best of the two worlds: a single round MHP where no malicious intermediary can steal coins. Moreover, Blitz provides the same privacy for sender and receiver as current MHP protocols do, is not prone to the wormhole attack and requires only constant collateral. Additionally, we construct MHPs using only digital signatures and a timelock functionality, both available at the core of virtually every cryptocurrency today. We provide the cryptographic details of Blitz and we formally prove its security. Furthermore, our experimental evaluation on a LN snapshot shows that (i) staggered collateral in LN leads to in between 4x and 33x more unsuccessful payments than the constant collateral in Blitz; (ii) Blitz reduces the size of the payment contract by 26%; and (iii) Blitz prevents up to 0.3 BTC (3397 USD in October 2020) in fees being stolen over a three day period as it avoids wormhole attacks by design.
    • Bitcoin-Compatible Virtual Channels
      Aumayr, L., Ersoy, O., Erwig, A., Faust, S., Hostáková, K., Maffei, M., Moreno-Sanchez, P., & Riahi, S. (2021). Bitcoin-Compatible Virtual Channels. In 2021 IEEE Symposium on Security and Privacy (SP). IEEE Symposium on Security and Privacy 2021, Oakland, United States of America (the). IEEE Computer Society.
      DOI: 10.1109/sp40001.2021.00097 Metadata ⯈Fulltext (preprint)
      Abstract
      Current permissionless cryptocurrencies such as Bitcoin suffer from a limited transaction rate and slow confirmation time, which hinders their large scale adoption. Payment channels are one of the most promising solutions to address these problems, as they allow two end-points of the channel to perform arbitrarily many payments in a peer-to-peer fashion while uploading only two transactions on the blockchain. This concept has been generalized into payment-channel networks where a path of payment channels is used to settle the payment between two users that might not share a channel between them. However, this approach requires the active involvement of each user in the path, making the system less reliable (they might be offline), more expensive (they charge fees per payment) and slower (intermediaries need to be actively involved in the payment). To mitigate this issue, recent work has introduced the concept of virtual channels, which involve intermediaries only in the initial creation of a bridge between payer and payee, who can later on independently perform arbitrarily many off-chain transactions. Unfortunately, existing constructions are only available for Ethereum, as they rely on its account model and Turing-complete scripting language. The realization of virtual channels in other blockchain technologies with limited scripting capabilities, like Bitcoin, was considered so far an open challenge. In this work, we present the first virtual channel protocols that are built on the UTXO-model and require a script language supporting only a digital signature scheme and a timelock functionality, being thus backwards compatible with virtually every cryptocurrency, including Bitcoin. We formalize the security properties of virtual channels as an ideal functionality in the Universal Composability framework, and prove that our protocol constitutes a secure realization thereof. We have prototyped and evaluated our protocol on the Bitcoin blockchain, demonstrating its efficiency: for n sequential payments, they require an off-chain exchange of 11+2⋅(n−1) transactions or a total of 4219+695⋅(n−1) bytes, with no on-chain footprint in the optimistic case.
    • Generalized Channels from Limited Blockchain Scripts and Adaptor Signatures
      Aumayr, L., Ersoy, O., Erwig, A., Faust, S., Hostáková, K., Maffei, M., Moreno-Sanchez, P., & Riahi, S. (2021). Generalized Channels from Limited Blockchain Scripts and Adaptor Signatures. In Lecture Notes in Computer Science (pp. 635–664). Springer.
      DOI: 10.1007/978-3-030-92075-3_22 Metadata
      Abstract
      Decentralized and permissionless ledgers offer an inherently low transaction rate, as a result of their consensus protocol demanding the storage of each transaction on-chain. A prominent proposal to tackle this scalability issue is to utilize off-chain protocols, where parties only need to post a limited number of transactions on-chain. Existing solutions can roughly be categorized into: (i) application-specific channels (e.g., payment channels), offering strictly weaker functionality than the underlying blockchain; and (ii) state channels, supporting arbitrary smart contracts at the cost of being compatible only with the few blockchains having Turing-complete scripting languages (e.g., Ethereum). In this work, we introduce and formalize the notion of generalized channels allowing users to perform any operation supported by the underlying blockchain in an off-chain manner. Generalized channels thus extend the functionality of payment channels and relax the definition of state channels. We present a concrete construction compatible with any blockchain supporting transaction authorization, time-locks and constant number of Boolean ∧ and ∨ operations -- requirements fulfilled by many (non-Turing-complete) blockchains including the popular Bitcoin. To this end, we leverage adaptor signatures -- a cryptographic primitive already used in the cryptocurrency literature but formalized as a standalone primitive in this work for the first time. We formally prove the security of our generalized channel construction in the Universal Composability framework. As an important practical contribution, our generalized channel construction outperforms the state-of-the-art payment channel construction, the Lightning Network, in efficiency. Concretely, it halves the off-chain communication complexity and reduces the on-chain footprint in case of disputes from linear to constant in the number of off-chain applications funded by the channel. Finally, we evaluate the practicality of our construction via a prototype implementation and discuss various applications including financially secured fair two-party computation.
    2020
    • Generalized Bitcoin-Compatible Channels
      Aumayr, L., Ersoy, O., Erwig, A., Faust, S., Hostáková, K., Maffei, M., Moreno-Sanchez, P., & Riahi, S. (2020). Generalized Bitcoin-Compatible Channels (2020/476).
      Metadata
      Abstract
      The widespread adoption of decentralized cryptocurrencies, such as Bitcoin or Ethereum, is currently hindered by their inherently limited transaction rate. One of the most prominent proposals to tackle this scalability issue are payment channels which allow mutually distrusted parties to exchange an arbitrary number of payments in the form of off-chain authenticated messages while posting only a limited number of transactions onto the blockchain. Specifically, two transactions suffice, unless a dispute between these parties occurs, in which case more on-chain transactions are required to restore the correct balance. Unfortunately, popular constructions, such as the Lightning network for Bitcoin, suffer from heavy communication complexity both off-chain and on-chain in case of dispute. Concretely, the communication overhead grows exponentially and linearly, respectively, in the number of applications that run in the channel. In this work, we introduce and formalize the notion of generalized channels for Bitcoin-like cryptocurrencies. Generalized channels significantly extend the concept of payment channels so as to perform off-chain any operation supported by the underlying blockchain. Besides the gain in expressiveness, generalized channels outperform state-of-the-art payment channel constructions in efficiency, reducing the communication complexity and the on-chain footprint in case of disputes to linear and constant, respectively. We provide a cryptographic instantiation of generalized channels that is compatible with Bitcoin, leveraging adaptor signatures -- a cryptographic primitive already used in the cryptocurrency literature but formalized as a standalone primitive in this work for the first time. We formally prove the security of our construction in the Universal Composability framework. Furthermore, we conduct an experimental evaluation, demonstrating the expressiveness and performance of generalized channels when used as building blocks for popular off-chain applications, such as channel splitting and payment-channel networks.
    2019
    • Automatisierte Prognose der Entwicklung von Kryptowährungspreisen
      Aumayr, L. (2019). Automatisierte Prognose der Entwicklung von Kryptowährungspreisen [Diploma Thesis, Technische Universität Wien]. reposiTUm.
      DOI: 10.34726/hss.2019.55455 Metadata
      Abstract
      Since the introduction of Bitcoin, cryptocurrencies have become very attractive as an alternative digital payment method and a highly speculative investment. With the rise in computational power and the growth of available data, the artificial intelligence concept of deep neural networks had a surge of popularity over the last years as well. With the introduction of the long short-term memory (LSTM) architecture, neural networks became more efficient in understanding long-term dependencies in data such as time series. In this thesis, we combine these two topics, by using neural networks to make a prognosis of cryptocurrency prices. In particular, we test if LSTM based neural networks can produce profitable trading signals for the cryptocurrency Ethereum. We experiment with different preprocessing techniques and different targets, both for price regression and trading signal classification. We evaluate two LSTM based networks and one convolutional neural network (CNN) LSTM hybrid. As data for training we use historical Ethereum price data in one-minute intervals from August 2017 to December 2018. We measure the performance of the models via backtesting, where we simulate trading on historic data not used for training based on the models predictions. We analyze that performance and compare it with the buy and hold strategy. The simulation is carried out on bullish, bearish and stagnating time periods. In the evaluation, we find the best performing target and pinpoint two preprocessing combinations that are most suitable for this task. We conclude that the CNN LSTM hybrid is capable of profitably forecasting trading signals for Ethereum, outperforming the buy and hold strategy by roughly 30%, while the performance of the other two models was disappointing.
Presentations (created while at TU Wien)
    2023
    • Thora: Atomic and Privacy-Preserving Multi-Channel Updates
      Aumayr, L., Abbaszadeh, K., & Maffei, M. (2023, February 28). Thora: Atomic and Privacy-Preserving Multi-Channel Updates. Network and Distributed System Security Symposium (NDSS) 2023, San Diego, United States of America (the).
      Metadata
      Abstract
      Most blockchain-based cryptocurrencies suffer from a heavily limited transaction throughput, which is a barrier to their growing adoption. Payment channel networks (PCNs) are one of the promising solutions to this problem. PCNs reduce the on-chain load of transactions and increase the throughput by processing many payments off-chain. In fact, any two users connected via a path of payment channels (i.e., joint addresses between the two channel end-points) can perform payments, and the underlying blockchain is used only when there is a dispute between users. Unfortunately, payments in PCNs can only be conducted securely along a path, which prevents the design of many interesting applications. Moreover, the most widely used implementation, the Lightning Network in Bitcoin, suffers from a collateral lock time linear in the path length, it is affected by security issues, and it relies on specific scripting features called Hash Timelock Contracts that hinders the applicability of the underlying protocol in other blockchains. In this work, we present Thora, the first Bitcoin-compatible off-chain protocol that enables the atomic update of arbitrary channels (i.e., not necessarily forming a path). This enables the design of a number of new off-chain applications, such as payments across different PCNs sharing the same blockchain, secure and trustless crowdfunding, and channel rebalancing. Our construction requires no specific scripting functionalities other than digital signatures and timelocks, thereby being applicable to a wider range of blockchains. We formally define security and privacy in the Universal Composability framework and show that our cryptographic protocol is a realization thereof. In our performance evaluation, we show that our construction requires only constant collateral, independently from the number of channels, and has only a moderate off-chain communication as well as computation overhead.
    • Sleepy Channels: Bitcoin-Compatible Bi-directional Payment Channels without Watchtowers
      Aumayr, L., Sri AravindaKrishnan Thyagarajan, Giulio Malavolta, Moreno-Sanchez, P., & Maffei, M. (2023, August 30). Sleepy Channels: Bitcoin-Compatible Bi-directional Payment Channels without Watchtowers [Conference Presentation]. The Science of Blockchain Conference 2023, Stanford, United States of America (the).
      Metadata
    • Sleepy Channels: Bi-directional Payment Channels without Watchtowers
      Aumayr, L., Sri AravindaKrishnan Thyagarajan, Giulio Malavolta, Moreno-Sanchez, P., & Maffei, M. (2023, February 28). Sleepy Channels: Bi-directional Payment Channels without Watchtowers [Poster Presentation]. Network and Distributed System Security Symposium (NDSS) 2023, United States of America (the).
      Metadata
    • Virtual Payment Channel Networks in Cryptocurrencies
      Aumayr, L. (2023, October 12). Virtual Payment Channel Networks in Cryptocurrencies [Presentation]. Lunchtime Seminar, Universität Innsbruck, Austria.
      Metadata
      Abstract
      Permissionless cryptocurrencies like Bitcoin are revolutionary but come with limitations - notably, they can handle only an extremely limited number of transactions per second. Enter Payment Channel Networks (PCNs), which let two users exchange numerous transactions with a minimal blockchain footprint. Imagine it as setting up a temporary tab with a friend, recording the final result instead of each tiny transaction. But PCNs are not perfect. They often require the use of intermediaries for routing payments, which means added fees and potential privacy concerns. Furthermore, their design primarily supports payments, leaving out numerous other fascinating blockchain applications. In this talk, we will dive into these challenges and introduce virtual channels (VCs) - a novel approach designed to address these limitations. VCs allow users to bypass intermediaries with temporary, off-chain channels and can host a wider range of applications, thus providing a cheap and generic solution for having scalable applications on Bitcoin and other cryptocurrencies
    • Thora: Atomic and Privacy-Preserving Multi-Channel Updates
      Aumayr, L., Abbaszadeh, K., & Maffei, M. (2023, August 30). Thora: Atomic and Privacy-Preserving Multi-Channel Updates [Conference Presentation]. The Science of Blockchain Conference 2023 (SBC’23), Stanford University, United States of America (the).
      Metadata
    • Breaking and Fixing Virtual Channels: Domino Attack and Donner
      Aumayr, L., Moreno-Sanchez, P., Kate, A., & Maffei, M. (2023, September 6). Breaking and Fixing Virtual Channels: Domino Attack and Donner [Presentation]. VISA Research - external research talks, Palo Alto, United States of America (the).
      Metadata
    2022
    • Generalized Channels from Limited Blockchain Scripts and Adaptor Signatures
      Aumayr, L., Oguzhan Ersoy, Erwig, A., Faust, S., Hostáková, K., Maffei, M., Moreno-Sanchez, P., & Riahi, S. (2022, August 30). Generalized Channels from Limited Blockchain Scripts and Adaptor Signatures [Conference Presentation]. The Science of Blockchain Conference 2022, Stanford, United States of America (the).
      Metadata
    • Blitz: Secure Multi-Hop Payments Without Two-Phase Commits
      Aumayr, L., Moreno-Sanchez, P., Kate, A., & Maffei, M. (2022, August 31). Blitz: Secure Multi-Hop Payments Without Two-Phase Commits [Conference Presentation]. The Science of Blockchain Conference 2022, Stanford, United States of America (the).
      Metadata
    • Thora: Atomic And Privacy-Preserving Multi-Channel Updates
      Aumayr, L., Kasra Abbaszadeh, & Maffei, M. (2022, October 31). Thora: Atomic And Privacy-Preserving Multi-Channel Updates [Poster Presentation]. Crypto Economics Security Conference, Berkeley, United States of America (the).
      Metadata
    • Sleepy Channels: Bi-directional Payment Channels without Watchtowers
      Aumayr, L., Sri AravindaKrishnan Thyagarajan, Giulio Malavolta, Moreno-Sanchez, P., & Maffei, M. (2022, October 31). Sleepy Channels: Bi-directional Payment Channels without Watchtowers [Poster Presentation]. Crypto Economics Security Conference, Berkeley, United States of America (the).
      Metadata
    • Evolution of Payment Channels
      Aumayr, L. (2022, July 27). Evolution of Payment Channels [Presentation]. DFINITY Foundation - research talks, Austria.
      Metadata
    2021
    • Donner: UTXO-Based Virtual Channels Across Multiple Hops
      Aumayr, L., Moreno-Sanchez, P., Kate, A., & Maffei, M. (2021, September 7). Donner: UTXO-Based Virtual Channels Across Multiple Hops [Presentation]. Bitcoin Sydney Socratic Seminar, Australia.
      Metadata
    • Blitz: Secure Multi-Hop Payments Without Two-Phase Commits
      Aumayr, L., Moreno-Sanchez, P., Kate, A., & Maffei, M. (2021, April 27). Blitz: Secure Multi-Hop Payments Without Two-Phase Commits [Presentation]. Bitcoin Sydney Socratic Seminar, Australia.
      Metadata
    • Blitz: Secure Multi-Hop Payments Without Two-Phase Commits
      Aumayr, L., Moreno-Sanchez, P., Kate, A., & Maffei, M. (2021, February 24). Blitz: Secure Multi-Hop Payments Without Two-Phase Commits [Presentation]. Decrypto Seminar, Unknown.
      Metadata
    • Designing Secure Payment Channel Schemes
      Aumayr, L. (2021, November 16). Designing Secure Payment Channel Schemes [Presentation]. Singapore Management University - Online Topic, Singapore.
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    • Beyond Payments in Payment Channel Networks
      Aumayr, L. (2021, November 16). Beyond Payments in Payment Channel Networks [Presentation]. Software Seminar Series (S3), Spain.
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    • Blitz: Secure Multi-Hop Payments Without Two-Phase Commits
      Aumayr, L., Moreno-Sanchez, P., Kate, A., & Maffei, M. (2021, May 26). Blitz: Secure Multi-Hop Payments Without Two-Phase Commits [Conference Presentation]. Theory and Practice of Blockchains, Unknown.
      Metadata
    • Off-chain Scaling of Cryptocurrencies
      Aumayr, L. (2021, December 9). Off-chain Scaling of Cryptocurrencies [Presentation]. VISP blockchain research meetup, Austria.
      Metadata