Entropia

user@openindiana:~$ time dd if=/dev/random of=/dev/zero bs=1024 count=1024
1024+0 records in
1024+0 records out
1048576 bytes (1,0 MB) copied, 56,3951 s, 18,6 kB/s

real 0m56.748s
user 0m0.009s
sys 0m56.382s
user@openindiana:~$ time dd if=/dev/urandom of=/dev/zero bs=1024 count=1024
1024+0 records in
1024+0 records out
1048576 bytes (1,0 MB) copied, 0,0697105 s, 15,0 MB/s

real 0m0.079s
user 0m0.003s
sys 0m0.076s