lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Wed, 5 Dec 2007 13:29:12 +0100
From:	Marc Haber <>
Subject: Re: Why does reading from /dev/urandom deplete entropy so much?

On Tue, Dec 04, 2007 at 05:18:11PM +0100, Adrian Bunk wrote:
> On Tue, Dec 04, 2007 at 12:41:25PM +0100, Marc Haber wrote:
> > While debugging Exim4's GnuTLS interface, I recently found out that
> > reading from /dev/urandom depletes entropy as much as reading from
> > /dev/random would. This has somehow surprised me since I have always
> > believed that /dev/urandom has lower quality entropy than /dev/random,
> > but lots of it.
> man 4 random

Thanks for this pointer, I was not aware of the documentation. After
reading this thread and the docs, I am now convinced that GnuTLS
should seed a PRNG from /dev/(u)random instead of using the entropy
directly. I will go filing a bug against GnuTLS.


Marc Haber         | "I don't trust Computers. They | Mailadresse im Header
Mannheim, Germany  |  lose things."    Winona Ryder | Fon: *49 621 72739834
Nordisch by Nature |  How to make an American Quilt | Fax: *49 3221 2323190
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists