[PATCH] Require minimum random data entropy when creating LUKS (#1073679)

Anne Mulhern amulhern at redhat.com
Tue Sep 9 13:36:55 UTC 2014





----- Original Message -----
> From: "Vratislav Podzimek" <vpodzime at redhat.com>
> To: "anaconda patch review" <anaconda-patches at lists.fedorahosted.org>
> Sent: Tuesday, September 9, 2014 7:54:14 AM
> Subject: Re: [PATCH] Require minimum random data entropy when creating LUKS	(#1073679)
> 
> On Mon, 2014-09-08 at 18:18 -0400, Anne Mulhern wrote:
> > 
> > 
> > 
> > ----- Original Message -----
> > > From: "Chris Lumens" <clumens at redhat.com>
> > > To: anaconda-patches at lists.fedorahosted.org
> > > Sent: Monday, September 8, 2014 1:05:43 PM
> > > Subject: Re: [PATCH] Require minimum random data entropy when creating
> > > LUKS	(#1073679)
> > > 
> > > > Maybe we should come up with some "Survey Anaconda Addon" for the
> > > > Progress Hub where we would ask users about their opinion and
> > > > experience
> > > > and let them check soething like "I agree with submitting my answers to
> > > > Anaconda developers". ;)
> > > 
> > > That is a pretty good idea.
> > > 
> > > In the past I've thought about having a check box on the betanag dialog
> > > that would have anaconda simply record your session and upload it
> > > somewhere, but I've always gotten stuck by the problem of where to put
> > > the recording before having it uploaded.
> > > 
> > > A survey would be much simpler, though we would have to very carefully
> > > word things in order to get good data.  Also we couldn't change the
> > > questions too often if we ever wanted them to be translated.  It's
> > > definitely worth considering, though.
> > > 
> > > - Chris
> > > _______________________________________________
> > > anaconda-patches mailing list
> > > anaconda-patches at lists.fedorahosted.org
> > > https://lists.fedorahosted.org/mailman/listinfo/anaconda-patches
> > > 
> > 
> > I believe I read that there is a problem with remote actions
> > to increase entropy. If the install is being controlled from a remote
> > keyboard, then the wiggles of the user at that keyboard are de-randomized
> > by transmission to the remote location, and therefore don't increase the
> > entropy.
> Well, generating network traffic is another good way to increase
> entropy, so I believe typing something on a keyboard even over a remote
> access should help.

Well, I can't remember where I saw the article, if I turn it up again I'll
let you know.

> 
> > 
> > If entropy is less than min entropy does TUI hang forever? It looks like
> > it.
> > Should these users instead be given some way to escape? It seems like there
> > is nothing to guarantee or even make likely that entropy will increase up
> > to
> > the minimum.
> Users can always escape by terminating the installation. Again, I have
> to point out that there shouldn't be any problems with a reasonable
> value of minimum required entropy (like 256 bits).
>

Is it an accessibility issue? If they can only type very slowly could
there be a problem? Or would entropy inexorably rise even if slowly?

> > 
> > Also, is it really necessary to show the user the percent of required
> > entropy in TUI once
> > enough is reached? It's hard for me to imagine that that's a point at which
> > they care
> > much.
> You mean like leaving it to [93 %] and then hang for a while before
> buffer is read and LUKS is created? That doesn't seem like a good idea
> to me. The final value >= 100 % is intentionally printed to give users
> the information that we have enough and they should stop typing and that
> things start to move on again.

I guess there might be confusion. I thought that the code
already prints "Done" immediately after the line we're discussing,
so there is not currently any danger of the hanging and waiting behaviour
you're describing if that line is removed. But maybe that "Done" is actually
debugging output?

If what you want to convey to the users is that they can stop typing now...
maybe you could say that directly instead of making them infer it from a line
like:

Available entropy: 256, Required entropy: 256 [100 %]

which will fairly closely resemble the long list of lines that they've been seeing
and hence may not communicate its true significance to them immediately.

I've actually been hitting random keys to increase entropy to 256
recently to test a bug and watching that output gets boring fast.

Also, maybe the line at the top should be more encouraging than informational.
If the users have to type random keys to get out of their situation, they should
probably get to read a line that tells them to do that, something like:

"To supply additional entropy, type at random. Do not hold keys down."

And the concluding line should be something like:

"Sufficient entropy generated. You may stop typing."

or something like that.

- mulhern

> 
> --
> Vratislav Podzimek
> 
> Anaconda Rider | RHCE | Red Hat, Inc. | Brno - Czech Republic
> 
> 
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