On Monday 27-October at 10:30 in E112 (campus Kirchberg) Ivan Pustogarov will give a talk on:
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 recommended to be changed frequently in order to increase
We present an efficient method to deanonymize Bitcoin users, which allows
to link user pseudonyms to the IP addresses where the transactions are
generated. Our techniques 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 Bitcoin
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 the attacker wants to be. We propose several
countermeasures to mitigate these new attacks.
Joint work with Alex Biryukov and Dmitry Khovratovich, to be presented at ACM Conference on Computer and Communications Security (CCS) in November this year.