Full Disclosure mailing list archives
Re: Re: SecureW2 TLS security problem
From: Valdis.Kletnieks () vt edu
Date: Tue, 04 Oct 2005 12:33:52 -0400
On Tue, 04 Oct 2005 15:08:40 +0200, Simon Josefsson said:
⢠The process ID of the current process requesting random data ⢠The thread ID of the current thread within the process requesting random
data
⢠A 32bit tick count since the system boot ⢠The current local date and time ⢠The current system time of day information consisting of the boot time, c
urrent time, time zone
... plus many more sources. I wonder if anybody has quantified the amount of entropy that could realistically be extracted from the mentioned sources.
Umm.. "not much". ;) For instance, note that there's "32 bit tick count" and "current time". Wandering over to Netcraft will give you the uptime - and how many times do they fold "current time" in there? Each additional one adds exactly zero entropy. Similarly, you get 4.5 bits of entropy *MAX* from 'time zone' - and if you can guess where the box is down to the continent, you're down to 2-3 tops, and possibly exactly 0 if you know the city.... Similarly, if "process ID" and "thread ID" are sequentially allocated integers, there's probably only 3-4 bits of entropy in the process ID (since at each reboot, everything starts in the same order each time)
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Current thread:
- Re: SecureW2 TLS security problem Simon Josefsson (Oct 04)
- Re: Re: SecureW2 TLS security problem Valdis . Kletnieks (Oct 04)
- Re: Re: SecureW2 TLS security problem Yvan Boily (Oct 04)
- Re: SecureW2 TLS security problem Simon Josefsson (Oct 06)
- Re: Re: SecureW2 TLS security problem Yvan Boily (Oct 04)
- Re: Re: SecureW2 TLS security problem Valdis . Kletnieks (Oct 04)