Re: [PATCH v4 0/5] /dev/random - a new approach

From	David Jaša <djasa@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v4 0/5] /dev/random - a new approach
Date	2016-06-21 14:30 +0200
Message-ID	<rMsYx-5LM-7@gated-at.bofh.it> (permalink)
References	<rKlHP-4PC-1@gated-at.bofh.it> <rKmkx-52w-19@gated-at.bofh.it> <rL2tr-7fP-21@gated-at.bofh.it> <rLpJo-5ix-1@gated-at.bofh.it>
Organization	Red Hat, Inc.

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Hi,

On So, 2016-06-18 at 10:44 -0400, Theodore Ts'o wrote:
> On Fri, Jun 17, 2016 at 03:56:13PM +0200, David Jaša wrote:
> > I was thinking along the lines that "almost every important package
> > supports FreeBSD as well where they have to handle the condition so
> > option to switch to Rather Break Than Generate Weak Keys would be nice"
> > - but I didn't expect that systemd could be a roadblock here. :-/
> 
> It wasn't just systemd; it also broke OpenWRT and Ubuntu Quantal
> systems from booting.
> 
> > I was also thinking of little devices where OpenWRT or proprietary
> > Linux-based systems run that ended up with predictable keys way too
> > ofter (or as in OpenWRT's case, with cumbersome tutorials how to
> > generate keys elsewhere).
> 
> OpenWRT and other embedded devices (a) generally use a single master
> oscillator to drive everything, and (b) often use RISC architectures
> such as MIPS.
> 
> Which means that arguments of the form ``the Intel L1 / L2 cache
> architecture is ****soooo**** complicated that no human could possibly
> figure out how they would affect timing calculations, and besides, my
> generator passes FIPS 140-2 tests (never mind AES(NSA_KEY, CNTR++)

this

> also passes the FIPS 140-2 statistical tests)'' --- which I normally
> have trouble believing --- are even harder for me to believe.
> 
> At the end of the day, with these devices you really badly need a
> hardware RNG.  

and this.

It seems much easier to me to embed AES(NSA_KEY, CNTR++) logic directly
to HW RNG compared to tweaking of every microarchitecture to make
jitter/maxwell/havege return known numbers that are going to be mixed
with other entropy anyway (won't they?). So if I put the bits together
correctly, HW RNG helps getting more random numbers but itself is
insufficient to ensure that random numbers are truly random...

Cheers,

David Jaša

> We can't generate randomness out of thin air.  The only
> thing you really can do requires user space help, which is to generate
> keys lazily, or as late as possible, so you can gather as much entropy
> as you can --- and to feed in measurements from the WiFi (RSSI
> measurements, MAC addresses seen, etc.)  This won't help much if you
> have an FBI van parked outside your house trying to carry out a
> TEMPEST attack, but hopefully it provides some protection against a
> remote attacker who isn't try to carry out an on-premises attack.
> 
> Cheers,
> 
> 						- Ted

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Re: [PATCH v4 0/5] /dev/random - a new approach David Jaša <djasa@redhat.com> - 2016-06-15 18:20 +0200
  Re: [PATCH v4 0/5] /dev/random - a new approach Stephan Mueller <smueller@chronox.de> - 2016-06-15 19:00 +0200
    Re: [PATCH v4 0/5] /dev/random - a new approach David Jaša <djasa@redhat.com> - 2016-06-17 16:00 +0200
      Re: [PATCH v4 0/5] /dev/random - a new approach Sandy Harris <sandyinchina@gmail.com> - 2016-06-17 17:30 +0200
        Re: [PATCH v4 0/5] /dev/random - a new approach Stephan Mueller <smueller@chronox.de> - 2016-06-18 10:30 +0200
      Re: [PATCH v4 0/5] /dev/random - a new approach Stephan Mueller <smueller@chronox.de> - 2016-06-18 10:30 +0200
      Re: [PATCH v4 0/5] /dev/random - a new approach Theodore Ts'o <tytso@mit.edu> - 2016-06-18 16:50 +0200
        Re: [PATCH v4 0/5] /dev/random - a new approach Stephan Mueller <smueller@chronox.de> - 2016-06-18 18:40 +0200
          Re: [PATCH v4 0/5] /dev/random - a new approach "Austin S. Hemmelgarn" <ahferroin7@gmail.com> - 2016-06-20 19:40 +0200
            Re: [PATCH v4 0/5] /dev/random - a new approach Stephan Mueller <smueller@chronox.de> - 2016-06-20 20:40 +0200
              Re: [PATCH v4 0/5] /dev/random - a new approach "Austin S. Hemmelgarn" <ahferroin7@gmail.com> - 2016-06-21 15:10 +0200
                Re: [PATCH v4 0/5] /dev/random - a new approach Stephan Mueller <smueller@chronox.de> - 2016-06-21 15:30 +0200
                Re: [PATCH v4 0/5] /dev/random - a new approach "Austin S. Hemmelgarn" <ahferroin7@gmail.com> - 2016-06-21 20:00 +0200
                Re: [PATCH v4 0/5] /dev/random - a new approach Stephan Mueller <smueller@chronox.de> - 2016-06-21 20:10 +0200
                Re: [PATCH v4 0/5] /dev/random - a new approach "Austin S. Hemmelgarn" <ahferroin7@gmail.com> - 2016-06-21 21:40 +0200
                Re: [PATCH v4 0/5] /dev/random - a new approach Stephan Mueller <smueller@chronox.de> - 2016-06-22 07:20 +0200
                Re: [PATCH v4 0/5] /dev/random - a new approach "Austin S. Hemmelgarn" <ahferroin7@gmail.com> - 2016-06-22 15:00 +0200
                Re: [PATCH v4 0/5] /dev/random - a new approach Stephan Mueller <smueller@chronox.de> - 2016-06-22 15:30 +0200
                Re: [PATCH v4 0/5] /dev/random - a new approach Tomas Mraz <tmraz@redhat.com> - 2016-06-21 15:30 +0200
                Re: [PATCH v4 0/5] /dev/random - a new approach Stephan Mueller <smueller@chronox.de> - 2016-06-21 19:30 +0200
                Re: [PATCH v4 0/5] /dev/random - a new approach "Austin S. Hemmelgarn" <ahferroin7@gmail.com> - 2016-06-21 20:00 +0200
                Re: [PATCH v4 0/5] /dev/random - a new approach Stephan Mueller <smueller@chronox.de> - 2016-06-21 20:10 +0200
                Re: [PATCH v4 0/5] /dev/random - a new approach "Austin S. Hemmelgarn" <ahferroin7@gmail.com> - 2016-06-21 20:30 +0200
                Re: [PATCH v4 0/5] /dev/random - a new approach Pavel Machek <pavel@ucw.cz> - 2016-06-21 15:50 +0200
                Re: [PATCH v4 0/5] /dev/random - a new approach "Austin S. Hemmelgarn" <ahferroin7@gmail.com> - 2016-06-21 19:20 +0200
        Re: [PATCH v4 0/5] /dev/random - a new approach David Jaša <djasa@redhat.com> - 2016-06-21 14:30 +0200

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