If the seed is to be based on time.time(), why not use something based on hash(time.time()) to avoid the 1/256 s resolution?

If there is a practical way to get pseudo-random data from the platform, it would be better to use that, rather than cooking up our own entropy from time.time(), PID, etc. But I guess that depends on the future of os.urandom() and friends.

In the meantime, limiting to os.urandom(256) seems reasonable, though I’m not a random number or cryptography expert.