Top all-time · #1265
Thomas Hühn
Personal blog · 2uo.deprogrammingsecurity
Thomas Hühn's personal blog at 2uo.de covers programming and security. Since 2014, 56 different Hacker News readers have linked it 151 times, most often “Myths about /dev/urandom”. No feed was found, so read it on the site itself.
Sometimes recommended · 6 of 40 sampled comments recommend it?
Why HN links it
Thomas Hühn's "Myths about urandom" post is linked to argue that /dev/urandom is as sound as /dev/random and that blocking on /dev/random is unnecessary. Commenters cite it as a reference on Linux random number generation.
Summarised by Claude from a sample of 40 HN comments that link here. Each comment is marked recommending, critical or neutral (citing without judging); how this works.
Most-linked posts?
- Myths about /dev/urandom32 people · 32 mentions · first linked 2014-03-07
- Myths about /dev/urandom (2014)18 people · 19 mentions · first linked 2017-08-22
- Myths about /dev/urandom (2014)7 people · 8 mentions · first linked 2018-08-17
- Statistical process control after W. Edwards Deming (2020)2 people · 6 mentions · first linked 2020-04-05
What Hacker News says?
My take on it: https://www.2uo.de/Books/316-bible-texts-illuminated/
Comment linking /Books/316-bible-texts-illuminated/
on “Knuth's Art of Computer Programming, V 4B, has gone into print”Submitted Myths about /dev/urandom as a story · 232 points
HN discussionWhen I read that tip I was thinking whether I should use it on https://www.2uo.de/russland-2013/ It's a longish travel report, lots of photos, interspersed with comments. I think it might be nice not to have all of them loaded in the beginning. Especially since random visitors probably won't read it till the end.
Comment linking /russland-2013/
on “HTML Tips (2020)”Submitted Myths about /dev/urandom (2014) as a story · 201 points
HN discussionThere's a lot of misinformation and cargo cult crypto programming, but the basic summary is that /dev/random information-theoretic security is unnecessary for most applications, but necessary for being able to know that you can produce every possible permutation of a deck of cards. http://www.2uo.de/myths-about-urandom/
Comment linking /myths-about-urandom/
on “Microsoft Solitaire was developed by a summer intern”Submitted Myths about /dev/urandom as a story · 186 points
HN discussionThere has been a number of studies ( http://www.2uo.de/myths-about-urandom ; I don't agree with everything but interesting reading anyway) showing that entropy from Linux random is not better than from urandom (once urandom has been properly seeded). For this reason, I patched my rndlinux.c GnuPG source code file to always use urandom. Makes key generation instantaneous. When a software is stupid, I don't want to in…
Comment linking /myths-about-urandom
on “GPG and Me”Submitted Influence – The Psychology of Persuasion as a story · 185 points
HN discussionHow does a blocking CSPRNG mitigate this attack? Again, it makes no sense to say that a CSPRNG can start "running low" on entropy. Here's what djb has to say about this: Cryptographers are certainly not responsible for this superstitious nonsense. Think about this for a moment: whoever wrote the /dev/random manual page seems to simultaneously believe that (1) we can't figure out how to deterministically expand one 2…
Comment linking /myths-about-urandom
on “An Almost-Secret Algorithm Researchers Used to Break Thousands of RSA Keys”Submitted The Now Habit (2015) as a story · 109 points
HN discussionI don't use much of AHK, but I love it. https://www.2uo.de/my-autohotkey-script/
Comment linking /my-autohotkey-script/
on “In Praise of AutoHotKey”Submitted The Now Habit as a story · 107 points
HN discussionWhat do you mean by "use up the nice entropy"? You can use /dev/urandom for cryptographic applications (in fact _you should_). Here's a nice article about it: http://www.2uo.de/myths-about-urandom/
Comment linking /myths-about-urandom/
on “Academics Make Theoretical Breakthrough in Random Number Generation”Submitted Statistical process control after W. Edwards Deming (2020) as a story · 81 points
HN discussionThen you might find that Thomas Hühn's approach helps you. * https://www.2uo.de/myths-about-urandom/ The "another crypto expert" mentioned by schoen is Daniel J. Bernstein, quoted directly by Hühn.
Comment linking /myths-about-urandom/
on “A wall of lava lamps helps encrypt the internet”Submitted Myths about /dev/urandom (2014) as a story · 80 points
HN discussion> this slightly time-saving but potentially dangerous choice? The one and only danger is during the machine's boot process, because while /dev/random and /dev/urandom use the same data: * on linux /dev/random has a silly and unfounded entropy estimator and will block at arbitrary points (used to be a fad at some point, but cryptographers have sworn off it e.g. Yarrow had an entropy estimator but Fortuna dropped it)…
Comment linking /myths-about-urandom/
on “LD_PRELOAD: The Hero We Need and Deserve”Submitted Myths about /dev/urandom (2014) as a story · 67 points
HN discussion1. The official man page. The /dev/random interface is considered a legacy interface, and /dev/urandom is preferred and sufficient in all use cases, with the exception of applications which require randomness during early boot time; for these applications, getrandom(2) must be used instead, because it will block until the entropy pool is initialized. 2. https://www.2uo.de/myths-about-urandom/
Comment linking /myths-about-urandom/
on “LD_PRELOAD: The Hero We Need and Deserve”Submitted Statistical process control after W. Edwards Deming as a story · 53 points
HN discussionThat blog post is old and inaccurate. It propagates myths about CSPRNGs that some have been trying to dispel, particularly Thomas Hühn [1] and djb [2]. /dev/urandom is the same cryptographically secure PRNG as /dev/random, except that /dev/random will superstitiously block when it thinks entropy has been "consumed". (CSPRNGs do not meaningfully "consume" entropy.) If you use /dev/random for the mythical warm fuzzies…
Comment linking /myths-about-urandom/
on “Math.random in V8 is broken”Submitted The Mind Map Book as a story · 36 points
HN discussionHere is a rough diagram which demonstrates it http://www.2uo.de/myths-about-urandom/structure-yes.png (from the detailed page http://www.2uo.de/myths-about-urandom/ ). /dev/random will block when the entropy estimate in low, but in a practical sense, the output of /dev/urandom and /dev/random are both random.
Comment linking /myths-about-urandom/
on “BoringSSL”Submitted The Deadline – notes about the Tom DeMarco book as a story · 12 points
HN discussionDo note that "exhausting the system's entropy pool" is a myth - entropy can't run out. In the bad old days, Linux kernel developers believed the myth and /dev/random would block if the kernel thought that entropy was low, but most applications (including crypto/rand) read from the non-blocking /dev/urandom instead. See https://www.2uo.de/myths-about-urandom/ for details. So don't let that stop you from using crypto/…
Comment linking /myths-about-urandom/
on “Secure Randomness in Go 1.22”Submitted Harmonized standards and EU directives (2014) as a story · 9 points
HN discussionThis is the best explanation of this issue that i know of: https://www.2uo.de/myths-about-urandom
Comment linking /myths-about-urandom
on “Removing the Linux /dev/random blocking pool”Submitted Statistical process control after W. Edwards Deming as a story · 8 points
HN discussionThis would also quiet a lot of the noise around the entropy estimation blocking in `/dev/random`. I mean, if basically everyone [1] agrees that you should just use `/dev/urandom/` because blocking on entropy estimation is misguided, then why not copy the behavior of every other Unix? [1]: http://www.2uo.de/myths-about-urandom/
Comment linking /myths-about-urandom/
on “/dev/random – a new approach”Submitted Beautifully Illustrated Children's Books as a story · 8 points
HN discussion
