Re: entropy
On Thu, Jan 07, 2010 at 06:40:02PM +0100, Roberto Ragusa wrote: You could investigate on how rngd works. rngd is your friend, if you have a source of entropy. There's a patch to rngd by Dell at the rngd web site [1] which uses the TPM chip (if present) to feed the entropy pool and keep it full. http://sourceforge.net/projects/gkernel/ -- Matt Domsch Technology Strategist, Dell Office of the CTO linux.dell.com www.dell.com/linux -- fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
entropy
Hi all, if I simply write to /dev/random, will that increase the entropy of my system? (I'm assuming that the data I'm writing are random and that somehow I got them). Thanks, Luca -- fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
Re: entropy
Luca wrote: Hi all, if I simply write to /dev/random, will that increase the entropy of my system? (I'm assuming that the data I'm writing are random and that somehow I got them). Wikipedia says so. My tests say no. In particular this brutal approach does not increase the entropy cat /dev/urandom /dev/random (it is stupid to do that, I know, but it's just a test) You could investigate on how rngd works. -- Roberto Ragusamail at robertoragusa.it -- fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
Re: entropy
On Thu, 2010-01-07 at 18:40 +0100, Roberto Ragusa wrote: Luca wrote: Hi all, if I simply write to /dev/random, will that increase the entropy of my system? (I'm assuming that the data I'm writing are random and that somehow I got them). Wikipedia says so. But random(4) does not. Is there some other authoritative source for this? poc -- fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
Re: entropy
On 10-01-07 12:40:02, Roberto Ragusa wrote: Luca wrote: Hi all, if I simply write to /dev/random, will that increase the entropy of my system? (I'm assuming that the data I'm writing are random and that somehow I got them). Wikipedia says so. My tests say no. In particular this brutal approach does not increase the entropy cat /dev/urandom /dev/random (it is stupid to do that, I know, but it's just a test) ... `man 4 random` says that the current entropy can be read and written from /dev/urandom, not /dev/random. This is used to preserver entropy across reboots. -- TonyN.:' mailto:tonynel...@georgeanelson.com ' http://www.georgeanelson.com/ -- fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
Re: entropy
On Thu, Jan 07, 2010 at 07:28:20PM +, Patrick O'Callaghan wrote: But random(4) does not. Is there some other authoritative source for this? Yes. :) http://lxr.linux.no/#linux+v2.6.32/drivers/char/random.c -- Matthew Miller mat...@mattdm.org Senior Systems Architect Cyberinfrastructure Labs / Instructional Research Computing Computing Information Technology Harvard School of Engineering Applied Sciences -- fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
Re: entropy
On Thu, Jan 07, 2010 at 06:40:02PM +0100, Roberto Ragusa wrote: Hi all, if I simply write to /dev/random, will that increase the entropy of my system? (I'm assuming that the data I'm writing are random and that somehow I got them). Wikipedia says so. My tests say no. How are you testing? The wikipedia article says: Non-random data is harmless, because only a privileged user can issue the ioctl needed to increase the entropy estimate. SO -- Matthew Miller mat...@mattdm.org Senior Systems Architect Cyberinfrastructure Labs / Instructional Research Computing Computing Information Technology Harvard School of Engineering Applied Sciences -- fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
Re: entropy
Tony Nelson wrote: On 10-01-07 12:40:02, Roberto Ragusa wrote: Luca wrote: Hi all, if I simply write to /dev/random, will that increase the entropy of my system? (I'm assuming that the data I'm writing are random and that somehow I got them). Wikipedia says so. My tests say no. In particular this brutal approach does not increase the entropy cat /dev/urandom /dev/random (it is stupid to do that, I know, but it's just a test) ... `man 4 random` says that the current entropy can be read and written from /dev/urandom, not /dev/random. This is used to preserver entropy across reboots. That's true. But as far as I can see neither writing to random nor to urandom will increase the entropy availability. After checking the sources of rngd, I found it uses a specific ioctl: ioctl(random_fd, RNDADDENTROPY, entropy); So I think Luca can inject entropy by using the same ioctl in his own application, or by using rngd in some way (you can tell it where to take entropy from). -- Roberto Ragusamail at robertoragusa.it -- fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
Re: entropy
On Thu, 2010-01-07 at 21:42 +0100, Roberto Ragusa wrote: Tony Nelson wrote: On 10-01-07 12:40:02, Roberto Ragusa wrote: Luca wrote: Hi all, if I simply write to /dev/random, will that increase the entropy of my system? (I'm assuming that the data I'm writing are random and that somehow I got them). Wikipedia says so. My tests say no. In particular this brutal approach does not increase the entropy cat /dev/urandom /dev/random (it is stupid to do that, I know, but it's just a test) ... `man 4 random` says that the current entropy can be read and written from /dev/urandom, not /dev/random. This is used to preserver entropy across reboots. That's true. But as far as I can see neither writing to random nor to urandom will increase the entropy availability. AFAIK the purpose of writing to /dev/urandom is simply to preserve the entropy state across reboots (at least that's the standard example). There's no implication that it increases the entropy. The effect of writing to /dev/random doesn't seem to be defined. poc -- fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
