* There is a bug in the older int2bytes implementation.
  I've raised an issue on bitbucket for that already.
  #11

 The pkcs1 file verification test fails if the behavior for
 int2bytes is corrected.

* In the following tests, the first speed test for
  each version of Python checked is the new
  implementation and the second is the old
  implementation.

$ ./speed.sh
int2bytes speed test
python2.5
1000 loops, best of 3: 315 usec per loop
100 loops, best of 3: 4.87 msec per loop
python2.6
10000 loops, best of 3: 170 usec per loop
100 loops, best of 3: 3.34 msec per loop
python2.7
10000 loops, best of 3: 169 usec per loop
100 loops, best of 3: 2.8 msec per loop
python3.2
10000 loops, best of 3: 169 usec per loop
100 loops, best of 3: 3.16 msec per loop