Messages in this thread | | | Date | Thu, 21 Feb 2013 16:07:12 +0200 | From | Phil Carmody <> | Subject | Re: [RFC][PATCH] Entropy generator with 100 kB/s throughput |
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Apologies if this is misthreaded, I had to hand-craft the headers.
> The patch offers an entropy generator based on CPU timing jitter. The > entropy collector has the following properties: > > * it does not maintain any state and therefore does not need any seed
What is this "pool" if it's not "state"?
> /* Entropy pool of the RNG which is filled upon each request for entropy */ > struct rand_data
And, from looking at jitterentropy_entropy_calc(), it seems to think that the [source producing the] following sequence of timestamps:
1000, 1010, 1030, 1050, 1060, 1080, 1090, 1110, 1120, ... i.e. with absolutely metronomic deltas of 10, 20, 10, 20, 10, 20, ...
has 4 bit of entropy per reading. I hope I don't have to explicitly say that it clearly it has 0 bits of entropy.
Entropy harvesting is quite hard - entropy estimation is unimaginably harder. Phil -- "In a world of magnets and miracles" -- Insane Clown Posse, Miracles, 2009. Much derided. "Magnets, how do they work" -- Pink Floyd, High Hopes, 1994. Lauded as lyrical geniuses.
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