Puzzled about random initialisation

[Robin Becker]

Tim Peters wrote:

> [Robin Becker]
> 
>>We've been queried about the randomness of some filenames we're producing.
>>I worked through and seemed to satisfy myself that random is being initialised
>>from the system time in C
>>       time(&now)
>>       init_genrand(self, (unsigned long)now);
>>
>>where now is a time expressed in integral seconds since the eopoch.
> 
> 

..... good stuff elided

> 641 unique random() values in 165923 attempts
> 641 unique time.time() values
> 
> Since it ran for 10 seconds, I'm seeing time.time() change about 64
> times per second.  I believe that's because this is a hyper-threaded
> box,  Whatever, if I had been able to start ~166000 instance of Python
> in that time, I would have seen only ~640 different seedings across
> them.

thanks for all this it makes things a lot clearer. Using time.time() makes it 
harder, but still not impossible to guess what values could have been generated. 
  The application should probably be using /dev/urandom to seed generators.
-- 
Robin Becker