[onerng talk] What is the entropy generation rate of the OneRNG?

Paul Campbell paul at taniwha.com
Wed Aug 19 23:12:16 BST 2015

On Thu, 20 Aug 2015 09:56:48 jld wrote:
> How many bits of entropy are generated per second?  And does that translate
> to the same number of bits being fed to /dev/random or is it a different
> measure?

at the moment at the default setting we're making ~350k bits/sec of data with 
~7.8 bits/byte of it actually being entropy - so ~340k bits/second

It's roughly the same amount as is being fed to /dev/[u]random - depending on 
the version of rngd you are using (if you're using the version that allows us 
to derate our data according to what we've measured you'll see 340k, if you 
have the older one it will register as 350k ... these differences are in the 
noise (pun not intended)) 

Whether you can actually get that data rate back out of /dev/[u]random 
probably depends on your CPU speed - I think the small (2k) kernel entropy 
pool makes it hard to stream data into it fast (all the flow control overhead 
tends to build up resulting in lots of context switches).

If you don't pull data from OneRNG at speed the data in its internal pool 
accumulates (it gets better, that 7.8bits/byte gets closer to 8)


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