Use rand.randbytes() instead of os.urandom()

[socketpair]

[mmarkk@asus home]$ python -m timeit -s 'import random' 'random.randbytes(8)'
5000000 loops, best of 5: 93.9 nsec per loop
[mmarkk@asus home]$ python -m timeit -s 'import os' 'os.urandom(8)'
1000000 loops, best of 5: 248 nsec per loop