simulating the broadcasting of Bitcoin transactions and first-hop reception by sybil attacker

randsim.py

import itertools
from random import randint

#p = 0.95
OTHER_NODES = 10000
MY_NODES = 4410
MY_CONNECTIONS = 8 * MY_NODES #my nodes are malicious and make 8 connections per peer
ALL_NODES = OTHER_NODES + MY_CONNECTIONS

NUM_BROADCASTED = 2

TRIALS = 1000000

TRIALS_WON = 0
TRIALS_LOST = 0

for _ in itertools.repeat(None, TRIALS):
    for x in itertools.repeat(None, NUM_BROADCASTED):
        select = randint(1, ALL_NODES)
        win = False
        #print select
        if select <= MY_CONNECTIONS:
            TRIALS_WON += 1
            #print "won!"
            win = True
            break

    if not win:
        TRIALS_LOST += 1
        #print "lost!"

print "Stats for {0} trials: ".format(TRIALS)
print "\t # trials in which I was one of the first-hop broadcasts: {0}".format(TRIALS_WON)
print "\t # trials in which I wasn't one of the first-hop broadcasts: {0}".format(TRIALS_LOST)
print "\t Fraction my nodes: {0}".format(float(TRIALS_WON)/(TRIALS_WON+TRIALS_LOST))