[Discuss] How do I add entropy?

Edward Ned Harvey (blu) blu at nedharvey.com
Sun Sep 7 10:25:54 EDT 2014


> From: discuss-bounces+blu=nedharvey.com at blu.org [mailto:discuss-
> bounces+blu=nedharvey.com at blu.org] On Behalf Of Bill Horne
> 
> Is there any way to speed the process? Short of putting up an antenna
> and counting bits of static, how can I accumulate random bits more
> quickly that by typing or moving the mouse?

Yes, you can read random bits from a bunch of other machines, download from online entropy sources and so forth, use http://tinhatrandom.org, there's a nice windows app (I wrote) to collect mouse entropy on a windows machine, etc...  There's also a list of online entropy sources.

Write to /dev/random

You mentioned in another email, that somebody suggested reading /dev/random and dumping to /dev/null.  This is exactly the opposite of correct and demonstrates the person who said it, to have no clue what they're talking about (or else they have a clue and they're being dicks for the sake of undermining your system security).

The more you read from /dev/random, the more you *reduce* the available entropy in your system entropy pool.

I *believe* (but haven't tested or otherwise confirmed) that the linux kernel honors bits written to /dev/random.

Also, shutdown into BIOS, and make sure your TPM is enabled.  Even if you use it for nothing, it is a hardware entropy source that the kernel can source from.

Keep your system busy, reading from disk and so forth, moving your mouse around, keyboard entry, network activity...  All are used as entropy sources.  (Unless you built your own kernel and failed to include entropy sources).



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