Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 1 Feb 2002 22:30:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 1 Feb 2002 22:30:40 -0500 Received: from adsl-63-197-0-76.dsl.snfc21.pacbell.net ([63.197.0.76]:17679 "HELO www.pmonta.com") by vger.kernel.org with SMTP id ; Fri, 1 Feb 2002 22:30:28 -0500 From: Peter Monta To: linux-kernel@vger.kernel.org In-Reply-To: (daw@mozart.cs.berkeley.edu) Subject: Re: Continuing /dev/random problems with 2.4 In-Reply-To: <20020201031744.A32127@asooo.flowerfire.com> <1012582401.813.1.camel@phantasy> <20020201202334.72F921C5@www.pmonta.com> Message-Id: <20020202033027.E30BE1C5@www.pmonta.com> Date: Fri, 1 Feb 2002 19:30:27 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org H. Peter Anvin wrote: > However, those aren't the main failure modes you need to be concerned > with. Antenna effects may actually be your biggest problem -- picking > up deterministic signals from other parts of the system. David Wagner wrote: > For instance, is there a risk that the audio data you read is strongly > correlated to 60Hz mains noise in some scenarios? ... I don't think predictable elements in the audio hurt anything. So long as there is a noise component, things are fine. Take the case of a half-full-scale 60 Hz sine wave plus a tiny bit of noise. No problem---each sample would still be worth 0.1 bit because the attacker can only guess the 60 Hz part: subtract this out and you've still got unpredictable noise. Same deal with crosstalk between channels, so long as it's reasonably small, say -20 dB or better (as it will be with any sane sound chip). > [ audio-entropyd ] Aha, nothing new under the sun. Cheers, Peter Monta - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/