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Re: One-line password generator

From Zenaan Harkness <zenaan@freedbms.net>
Newsgroups linux.debian.user
Subject Re: One-line password generator
Date 2017-08-29 04:40 +0200
Message-ID <ujEBz-5eu-7@gated-at.bofh.it> (permalink)
References <ujoGt-3Tj-5@gated-at.bofh.it> <ujp9y-4iA-75@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Mon, Aug 28, 2017 at 12:04:51PM +0200, Thomas Schmitt wrote:
> Hi,
> 
> Curt wrote:
> > Here's a fresh (20 July of this year) view by Theodore Ts'o:
> > https://lkml.org/lkml/2017/7/20/993
> 
> An opinion of substantial weight, indeed.
> 
> Nevertheless it would be more interesting to learn the reason why
> Linux did not simply make /dev/random behave like /dev/urandom long
> ago.

Because that would obfuscate the difference in nature between
the two.

AIUI /dev/random is simply the input feed to /dev/urandom and the
fact /dev/random is world readable is now an historic artifact, but
also quite possibly still useful in certain, very specific/ narrow,
circumstances.

The main problem is folks not knowing which one to use.

There are no shortcuts in the world of secure algorithms - that is,
if you want security/ secure software, you -must- know the nature of
your inputs, and /dev/random vs /dev/urandom provides this
(essential) distinction.


> And again, the argumentation of Theodore is that there is always
> enough entropy at hand.

Unclear wording. I would say Ted Ts'o is making sure that
/dev/urandom delivers on its API promise/ expectation, which is
really important, and great to know that Ts'o is on this!


> I understand that in this situation there is no difference
> between /dev/random and /dev/urandom.

No.

Here's Ted Ts'o (from above link):

  "I don't really care about /dev/random performance.  What's is
  **far** more important is that the entropy estimations behave
  correctly, across all of Linux's architectures, while the kernel is
  going through startup, before CRNG is declared initialized."

/dev/random performance/ api promise is "deliver truly random bits,
even if this is slow to do so, since we'll be using these bits in
absolutely critical places, such as seeding /dev/urandom"


> The difference appears only when the assumption of wealth is not
> fulfilled.

... parse fail


> Also one should note that Theodore uses the argument of a
> deprecated /dev/random as answer to a side note of his discussion
> partner, not as general statement.

But see his general statement above, which is almost the same thing
as "if you want performance, consider /dev/random deprecated", i.e.
he said "I don't really care about /dev/random performance."


> The main point of Stephan Müller is that the system could collect
> more entropy. The answer of Theodore is that it already collects
> more than enough and does not have to care about being drained by
> /dev/random because that draining is deprecated.

Exactly - don't use /dev/random, use /dev/urandom instead, as
designed, and as has been made publicly clear for ~10 years now.


> So one would have to ask him, whether this opinion does not hold
> under all circumstances or what else blocks him from just making
> both mechanisms equal.

Hopefully the above explains the principles involved.

If for any reason you want high speed "hardware/ physical random"
number stream, then you will have to go for a HRNG, and as Ted points
out in the above link, there are many drivers for these in the kernel
already - in other words, EVERY use case is abundantly provided for
by the Linux kernel.

Causing /dev/random to be the same as /dev/urandom would only make
sense if the current /dev/random implementation were made completely
private i.e. "internal to the kernel and not accessible by userspace"
- then /dev/random could simply be a symlink to /dev/urandom - but
there are disadvantages to doing this, not the least of which would
be certain very specific yet limited use cases for which the existing
/dev/random is an essential dependency!


> (Normally i would dare to approach him. But i guess he is already
> annoyed by the topic and man page reading cowards like me.)


  Confront the man page!
  And Wikipedia too ...
  Then write, your Haiku :)


> Have a nice day :)

You too, and a Haiku new.

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Thread

One-line password generator Mario Castelán Castro <marioxcc.MT@yandex.com> - 2017-08-22 17:10 +0200
  Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-08-22 21:50 +0200
    Re: One-line password generator <tomas@tuxteam.de> - 2017-08-22 22:10 +0200
      Re: One-line password generator John Hasler <jhasler@newsguy.com> - 2017-08-22 22:50 +0200
        Re: One-line password generator Jude DaShiell <jdashiel@panix.com> - 2017-08-23 14:40 +0200
    Re: One-line password generator Mario Castelán Castro <marioxcc.MT@yandex.com> - 2017-08-22 22:20 +0200
      Re: One-line password generator Mario Castelán Castro <marioxcc.MT@yandex.com> - 2017-08-22 22:20 +0200
      Re: One-line password generator Mario Castelán Castro <marioxcc.MT@yandex.com> - 2017-08-22 22:30 +0200
        Re: One-line password generator Glenn English <ghe2001@gmail.com> - 2017-08-23 22:40 +0200
      Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-08-23 00:40 +0200
        Re: One-line password generator Lck Ras <likcoras@riseup.net> - 2017-08-23 02:30 +0200
          Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-08-23 19:20 +0200
            Re: One-line password generator Lck Ras <likcoras@riseup.net> - 2017-08-24 03:00 +0200
        Re: One-line password generator Mario Castelán Castro <marioxcc.MT@yandex.com> - 2017-08-23 17:20 +0200
          Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-08-23 19:00 +0200
            Re: One-line password generator Mario Castelán Castro <marioxcc.MT@yandex.com> - 2017-08-23 20:00 +0200
              Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-08-23 21:20 +0200
                Re: One-line password generator Mario Castelán Castro <marioxcc.MT@yandex.com> - 2017-08-24 01:10 +0200
                Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-08-24 19:50 +0200
                Re: One-line password generator David Wright <deblis@lionunicorn.co.uk> - 2017-08-25 03:00 +0200
                Re: One-line password generator Curt <curty@free.fr> - 2017-08-25 10:50 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-25 11:30 +0200
                Re: One-line password generator Mario Castelán Castro <marioxcc.MT@yandex.com> - 2017-08-25 15:40 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-25 16:50 +0200
                Re: One-line password generator Mario Castelán Castro <marioxcc.MT@yandex.com> - 2017-08-25 18:10 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-25 19:20 +0200
                Re: One-line password generator Mario Castelán Castro <marioxcc.MT@yandex.com> - 2017-08-25 20:10 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-25 20:50 +0200
                Re: One-line password generator Mario Castelán Castro <marioxcc.MT@yandex.com> - 2017-08-25 21:00 +0200
                Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-08-25 19:00 +0200
                Re: One-line password generator Mario Castelán Castro <marioxcc.MT@yandex.com> - 2017-08-25 19:00 +0200
                Re: One-line password generator Mario Castelán Castro <marioxcc.MT@yandex.com> - 2017-08-25 19:20 +0200
                Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-08-25 20:20 +0200
                Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-08-25 19:20 +0200
    Re: One-line password generator Jape Person <japers@comcast.net> - 2017-08-22 22:20 +0200
      Re: One-line password generator Jude DaShiell <jdashiel@panix.com> - 2017-08-23 14:40 +0200
    Re: One-line password generator Mike McClain <mike.junk.46@att.net> - 2017-08-23 03:10 +0200
  Re: One-line password generator Teemu Likonen <tlikonen@iki.fi> - 2017-08-23 06:10 +0200
  Re: One-line password generator Aaron Toponce <aaron.toponce@gmail.com> - 2017-08-23 21:20 +0200
    Re: One-line password generator Greg Wooledge <wooledg@eeg.ccf.org> - 2017-08-23 21:30 +0200
      Re: One-line password generator Aaron Toponce <aaron.toponce@gmail.com> - 2017-08-23 21:40 +0200
        Re: One-line password generator Fungi4All <fungilife@protonmail.com> - 2017-08-23 22:50 +0200
          Re: One-line password generator Terence <terence.john@gmail.com> - 2017-08-23 23:40 +0200
  Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-08-26 20:30 +0200
    Re: One-line password generator Nicolas George <george@nsup.org> - 2017-08-26 20:40 +0200
      Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-08-26 21:10 +0200
        Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-08-27 16:00 +0200
    Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-26 21:20 +0200
      Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-08-27 16:00 +0200
        Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-27 17:10 +0200
          Re: One-line password generator Curt <curty@free.fr> - 2017-08-27 20:10 +0200
          Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-08-27 20:10 +0200
            Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-27 21:10 +0200
              Re: One-line password generator Andy Smith <andy@strugglers.net> - 2017-08-28 00:00 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-28 09:40 +0200
                Re: One-line password generator Curt <curty@free.fr> - 2017-08-28 11:40 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-28 12:10 +0200
                Re: One-line password generator Andy Smith <andy@strugglers.net> - 2017-08-28 13:50 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-28 15:20 +0200
                Re: One-line password generator Zenaan Harkness <zenaan@freedbms.net> - 2017-08-29 04:40 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-29 09:10 +0200
                Re: One-line password generator Zenaan Harkness <zenaan@freedbms.net> - 2017-08-29 10:50 +0200
                Re: One-line password generator Zenaan Harkness <zenaan@freedbms.net> - 2017-08-29 11:00 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-29 12:50 +0200
                Re: One-line password generator Zenaan Harkness <zenaan@freedbms.net> - 2017-08-29 13:00 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-29 14:30 +0200
                Re: One-line password generator Zenaan Harkness <zenaan@freedbms.net> - 2017-08-30 03:50 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-30 12:40 +0200
                Re: One-line password generator Andy Smith <andy@strugglers.net> - 2017-08-29 14:10 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-29 15:00 +0200
                Re: One-line password generator Zenaan Harkness <zenaan@freedbms.net> - 2017-08-30 03:50 +0200
                Re: One-line password generator Greg Wooledge <wooledg@eeg.ccf.org> - 2017-08-30 14:20 +0200
                Re: One-line password generator Gene Heskett <gheskett@shentel.net> - 2017-08-30 14:50 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-30 15:20 +0200
                Re: One-line password generator Gene Heskett <gheskett@shentel.net> - 2017-08-30 15:30 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-30 15:50 +0200
                Re: One-line password generator Gene Heskett <gheskett@shentel.net> - 2017-08-30 16:00 +0200
                Re: One-line password generator Greg Wooledge <wooledg@eeg.ccf.org> - 2017-08-30 16:10 +0200
                Re: One-line password generator Gene Heskett <gheskett@shentel.net> - 2017-08-30 18:50 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-30 16:30 +0200
                Re: One-line password generator Gene Heskett <gheskett@shentel.net> - 2017-08-30 20:10 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-30 23:00 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-09-01 10:40 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-09-01 10:50 +0200
                Re: One-line password generator Curt <curty@free.fr> - 2017-08-30 16:30 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-30 17:00 +0200
                Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-08-30 20:00 +0200
                Re: One-line password generator Zenaan Harkness <zenaan@freedbms.net> - 2017-08-29 11:00 +0200
            Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-27 21:20 +0200
              Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-08-29 21:20 +0200
                Re: One-line password generator Reco <recoverym4n@gmail.com> - 2017-08-29 21:40 +0200
                Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-08-29 22:00 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-29 23:00 +0200
                Re: One-line password generator Curt <curty@free.fr> - 2017-08-30 10:50 +0200
                Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-08-30 12:40 +0200
                Re: One-line password generator Reco <recoverym4n@gmail.com> - 2017-08-30 00:00 +0200
                Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-08-31 21:10 +0200
                Re: One-line password generator Fungi4All <fungilife@protonmail.com> - 2017-08-31 21:20 +0200
                Re: One-line password generator Reco <recoverym4n@gmail.com> - 2017-08-31 21:40 +0200
    Re: One-line password generator Mario Castelán Castro <marioxcc.MT@yandex.com> - 2017-08-27 04:20 +0200
      Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-08-27 16:00 +0200
        Re: One-line password generator Mario Castelán Castro <marioxcc.MT@yandex.com> - 2017-08-27 16:40 +0200
  Re: One-line password generator Mario Castelán Castro <marioxcc.MT@yandex.com> - 2017-09-01 17:00 +0200
    Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-09-01 21:50 +0200
      Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-09-01 23:50 +0200
        Re: One-line password generator Jude DaShiell <jdashiel@panix.com> - 2017-09-02 11:50 +0200
          Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-09-02 13:00 +0200
            Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-09-02 19:20 +0200
              Re: One-line password generator Jude DaShiell <jdashiel@panix.com> - 2017-09-02 20:30 +0200
              Re: One-line password generator "Thomas Schmitt" <scdbackup@gmx.net> - 2017-09-02 21:00 +0200
                Re: One-line password generator Brian <ad44@cityscape.co.uk> - 2017-09-02 22:00 +0200
      Re: One-line password generator Zenaan Harkness <zenaan@freedbms.net> - 2017-09-02 01:50 +0200
    Re: One-line password generator Zenaan Harkness <zenaan@freedbms.net> - 2017-09-02 01:50 +0200
      Re: One-line password generator Mario Castelán Castro <marioxcc.MT@yandex.com> - 2017-09-02 04:40 +0200
        Re: One-line password generator Zenaan Harkness <zenaan@freedbms.net> - 2017-09-02 05:40 +0200
          Re: One-line password generator Mario Castelán Castro <marioxcc.MT@yandex.com> - 2017-09-02 16:40 +0200
            Re: One-line password generator Zenaan Harkness <zenaan@freedbms.net> - 2017-09-04 01:10 +0200

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