[Cryptography] Deanonymisation of Clients in Bitcoin P2P Network: Biryukov Khovratovich, Pustogarov

[Robert Hettinga]

http://orbilu.uni.lu/bitstream/10993/18679/1/Ccsfp614s-biryukovATS.pdf

Deanonymisation of Clients in Bitcoin P2P Network

Alex Biryukov Dmitry Khovratovich Ivan Pustogarov

University of Luxembourg
{alex.biryukov, dmitry.khovratovich, ivan.pustogarov}@uni.lu

ABSTRACT

Bitcoin is a digital currency which relies on a distributed set of miners to mint coins and on a peer-to-peer network to broadcast transactions. The identities of Bitcoin users are hidden behind pseudonyms (public keys) which are rec- ommended to be changed frequently in order to increase transaction unlinkability.

We present an efficient method to deanonymize Bitcoin users, which allows to link user pseudonyms to the IP ad- dresses where the transactions are generated. Our tech- niques work for the most common and the most challenging scenario when users are behind NATs or firewalls of their ISPs. They allow to link transactions of a user behind a NAT and to distinguish connections and transactions of different users behind the same NAT. We also show that a natural countermeasure of using Tor or other anonymity services can be cut-off by abusing anti-DoS countermeasures of the Bit- coin network. Our attacks require only a few machines and have been experimentally verified. The estimated success rate is between 11% and 60% depending on how stealthy an attacker wants to be. We propose several countermeasures to mitigate these new attacks.