Exploiting Transaction Accumulation and Double Spends for Topology Inference in Bitcoin
Bitcoin relies on a peer-to-peer network for communication between participants. Knowledge of the network topology is of scientific interest but can also facilitate attacks on the users’ anonymity and the system’s availability. We present two approaches f
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Abstract. Bitcoin relies on a peer-to-peer network for communication between participants. Knowledge of the network topology is of scientific interest but can also facilitate attacks on the users’ anonymity and the system’s availability. We present two approaches for inferring the network topology and evaluate them in simulations and in real-world experiments in the Bitcoin testnet. The first approach exploits the accumulation of multiple transactions before their announcement to other peers. Despite the general feasibility of the approach, simulation and experimental results indicate a low inference quality. The second approach exploits the fact that double spending transactions are dropped by clients. Experimental results show that inferring the neighbors of a specific peer is possible with a precision of 71% and a recall of 87% at low cost.
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Introduction
Bitcoin [9] is a digital currency system that stores transactions in a blockchain. Participants are connected via a peer-to-peer (P2P) network in order to exchange transactions and blocks. The topology of the P2P network is an important aspect in ensuring anonymity of users and robustness against denial of service attacks [5], double spending attacks [6], and attacks on mining [3,10]. For instance, knowledge of the network topology can enable network based attacks on anonymity [1,4,7]. In this work we present and analyze two approaches that aim at inferring the topology of the publicly reachable Bitcoin network. Peers that are not reachable (e.g., peers that do not accept incoming connections) as well as private networks such as FIBRE1 or mining pool networks are not covered by our work. Neither of the presented approaches rely on the existence of side channels (e.g., peer discovery), because they exploit properties of the implementation of the flooding protocol used for transaction propagation.
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http://bitcoinfibre.org/.
c International Financial Cryptography Association 2019 A. Zohar et al. (Eds.): FC 2018 Workshops, LNCS 10958, pp. 113–126, 2019. https://doi.org/10.1007/978-3-662-58820-8_9
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M. Grundmann et al.
Related Work
Topology inference in Bitcoin has been the subject of several previous works. Peer discovery in Bitcoin allows clients to query their neighbors for IP addresses of other peers in order to establish connections to them. The queried neighbor then sends a list with IP addresses along with a lastseen timestamp. Until March 2015 the timestamp was not randomized sufficiently and allowed Miller et al. [8] to exploit this mechanism and infer the network topology. Peer discovery can also be exploited for topology inference by sending marker IP addresses to remote peers [1]. Neudecker et al. [11] performed a timing analysis of the propagation of transactions in order to infer the network topology. By connecting to all reachable peers of the network and observing the timestamps of receptions of certain transactions, the path of the transaction and thereby the connections between peers can be inferred. This approach requires connections t
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