Note that we assume so far that A does not participate in the mining process. In case A is a miner or compromises a node that participates in the mining process, then the advantage of A in mounting double-spending attacks on zero-confirmation transactions can further increase depending on the mining power available to the adversary.

Namely, Finney [17] describes a double-spending attack in Bitcoin where the attacker includes in his or her generated blocks a number of transactions that transfer some coins between his or her own addresses. These blocks are only released in the network after the attacker double-spends the same coins using zero-confirmation payments and acquires a given service.

Clearly, the success probability of this attack depends on the mining power available to the adversary. Given the tremendous computing power that supports the current Bitcoin network,^{[1]}^{[2]} the success probability of an adversary that does not control a considerable fraction of the mining power is only negligible.

[1] Here, “Location” denotes the location of V, “connections” denote the number of V’s connections.The success probability is adapted from the findings of [1] and is interpolated by means ofexperiments using Amazon nodes.

[2] The hashing rate in Bitcoin amounted to 0.5-1016 hashes per second in November 2015.