[149338] in cryptography@c2.net mail archive
Re: [Cryptography] cheap sources of entropy
daemon@ATHENA.MIT.EDU (James A. Donald)
Mon Feb 3 19:35:30 2014
X-Original-To: cryptography@metzdowd.com
Date: Tue, 04 Feb 2014 08:44:51 +1000
From: "James A. Donald" <Jamesd@echeque.com>
To: cryptography@metzdowd.com
In-Reply-To: <20140203062225.2036BFFD0@a-pb-sasl-quonix.pobox.com>
Errors-To: cryptography-bounces+crypto.discuss=bloom-picayune.mit.edu@metzdowd.com
On 2014-02-03 16:22, Bill Stewart wrote:
>
> I'm mainly worried about the "new virtual machine, cloned from a
> standard image" case,
> which needs to set up ssh keys, ssl keys, and seed /dev/random before
> it's ready to deal with the rest of the world
> in ways that would give it some more entropy to work with.
The normal case of replicating an up and running VM is scalable cloud
service, where one increases machines to meet demand or decrease
machines to save money. In such case, they will all have the same keys
as the original, which keys you generated long after booting up the
original.
If we have an image of an up and running machine, which we clone using
copy on write, how does it know to set up new keys? There has to be a
command "generate new identity". When telling the cloned image to
generate new keys, give it some randomness. I don't think this case
arises in practice
If we have an image of a bootable disk, cloning is going to be IO bound,
and timing of events will contain the inherent randomness of the
physical processes involved in getting the data.
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