Performance of /dev/urandom and /dev/random

Mihir Pandya mihir.m.pandya at
Thu Sep 27 19:09:03 EDT 2012

Hey guys,

I'm interested to know why generating cryptographically secure random
numbers takes so long, particularly in my case. I have two Java classes
that are generating a million random numbers. One is generating random
numbers regularly while the other is using SecureRandom to generate the
numbers. The SecureRandom method is taking almost double the time and I
realised that it's because the method reads from /dev/urandom (not sure
which) and obtains its random numbers from the entropy pool there.

I wanted to know where I can read about the exact mechanism used to
generate the cryptographically secure random numbers through SecureRandom
and if there is any way to make it faster.

Mihir Pandya
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