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best way to create entropy?
- Subject: best way to create entropy?
- From: pelzi at pelzi.net (Jussi Peltola)
- Date: Fri, 12 Oct 2012 03:43:35 +0300
- In-reply-to: <CAHsqw9vBE-St1gXfS23-2DeFRx_jK7w2p8cWNbU0tr230=7cew@mail.gmail.com>
- References: <CAH_OBiffdqVmwspu9f2uzr_cqnExuA_sLp=d0QhOxQWzkSgOZA@mail.gmail.com> <CAAAwwbWAoy60NBquCX8TeOcChC8Odpw3mRBAgzkcTSqFAN20wg@mail.gmail.com> <CAHsqw9vBE-St1gXfS23-2DeFRx_jK7w2p8cWNbU0tr230=7cew@mail.gmail.com>
On Thu, Oct 11, 2012 at 05:25:37PM -0700, Jonathan Lassoff wrote:
> Yes, but then you're also introducing a way for an external attacker
> to transmit data that can be mixed into your entropy pool.
XORring predictable data to random data does not yield a predictable
result. /dev/random is world writable so if writing to it causes the
random generator to output something predictable it's a bug that needs
to be fixed. Also, an analog TV receiver will always have some noise that is
not predictable even if you are transmitting a known signal to it.
If you seriously need good entropy for cryptography, I think you will not
ask about it on nanog, and I'd be very wary of cheap hardware RNGs too.