Date: Sun, 1 Oct 1995 13:50:21 -0400 (EDT) From: "Jonathan M. Bresler" <jmb@kryten.Atinc.COM> To: Mark Murray <mark@grondar.za> Cc: Bruce Evans <bde@zeta.org.au>, hackers@freebsd.org, mark@grondar.za Subject: Re: How to get to the hardware? Message-ID: <Pine.3.89.9510011341.B15632-0100000@kryten.atinc.com> In-Reply-To: <199510011230.OAA04285@grumble.grondar.za>
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On Sun, 1 Oct 1995, Mark Murray wrote: > * The second function uses the inter-interrupt timing as random > * inputs to the entropy pool. Note that not all interrupts are good > * sources of randomness! For example, the timer interrupts is not a the interrupt from a network card, provided one is available and connected to an active segment, may be a very good choice of inter-interrupt time period randomness. if a net device is not available, the time between key strokes is another source. this time period is used as a source of random bits by pgp when generating key pairs. > * good choice, because the periodicity of the interrupts is to > * regular, and hence predictable to an attacker. Disk interrupts are > * a better measure, since the timing of the disk interrupts are more > * unpredictable. The routines try to estimate how many bits of > * randomness a particular interrupt channel offers, by keeping track > * of the first and second order deltas in the interrupt timings. > > BTW - would you be prepared to review this code before committal? i would like to see a copy ;) Jonathan M. Bresler jmb@kryten.atinc.com | Analysis & Technology, Inc. FreeBSD Postmaster jmb@FreeBSD.Org | 2341 Jeff Davis Hwy play go. | Arlington, VA 22202 ride bike. hack FreeBSD.--ah the good life | 703-418-2800 x346
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