linux-kernel - Reading entropy_avail file appears to consume entropy

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <4BA3BE9B.5050201@computer.org>
Date:	Fri, 19 Mar 2010 19:12:43 +0100
From:	Jan Ceuleers <jan.ceuleers@...puter.org>
To:	linux-kernel@...r.kernel.org
Subject: Reading entropy_avail file appears to consume entropy

I'm using the 2.6.31 kernel that comes with Ubuntu 9.10.

If I

   # watch cat /proc/sys/kernel/random/entropy_avail

then the size of the entropy pool falls rapidly (by more than 200 bytes per 2s interval). It settles down around 160 bytes.

The machines on which I've done the above experiment are otherwise idle. They are also dramatically different from one another: one is a laptop, the other is an embedded device (a Soekris net5501).

Is this supposed to happen?

Thanks, Jan
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/