  Bitcoin has created a new exchange paradigm within which financial
transactions can be trusted without an intermediary. This premise of a free
decentralized transactional network however requires, in its current
implementation, unrestricted access to the ledger for peer-based transaction
verification. A number of studies have shown that, in this pseudonymous
context, identities can be leaked based on transaction features or off-network
information. In this work, we analyze the information revealed by the pattern
of transactions in the neighborhood of a given entity transaction. By
definition, these features which pertain to an extended network are not
directly controllable by the entity, but might enable leakage of information
about transacting entities. We define a number of new features relevant to
entity characterization on the Bitcoin Blockchain and study their efficacy in
practice. We show that even a weak attacker with shallow data mining knowledge
is able to leverage these features to characterize the entity properties.
