From owner-freebsd-hackers@freebsd.org Sun Dec 6 23:36:35 2020 Return-Path: Delivered-To: freebsd-hackers@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 723E7470454 for ; Sun, 6 Dec 2020 23:36:35 +0000 (UTC) (envelope-from dave@jetcafe.org) Received: from fedex2.jetcafe.org (fedex2.jetcafe.org [205.147.26.23]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA512 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "fedex2.jetcafe.org", Issuer "Let's Encrypt Authority X3" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4Cq2ry1PWsz3JBt for ; Sun, 6 Dec 2020 23:36:33 +0000 (UTC) (envelope-from dave@jetcafe.org) X-Envelope-To: Received: from bigus.dream-tech.com (bigus.jetcafe.org [205.147.26.7]) by fedex2.jetcafe.org (8.15.2/8.15.2) with ESMTPS id 0B6NaPf7095607 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Sun, 6 Dec 2020 15:36:26 -0800 (PST) (envelope-from dave@jetcafe.org) Date: Sun, 6 Dec 2020 15:36:25 -0800 From: Dave Hayes To: freebsd-hackers@freebsd.org Subject: arc4random initialization Message-ID: <20201206153625.13e349a8@bigus.dream-tech.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Spam-Score: -1 ( out of 5.1) ALL_TRUSTED,SHORTCIRCUIT X-Spam-Checker-Version: SpamAssassin version 3.4.4-jetcafeglobal X-Scanned-By: MIMEDefang 2.83 X-Rspamd-Queue-Id: 4Cq2ry1PWsz3JBt X-Spamd-Bar: - Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=pass (mx1.freebsd.org: domain of dave@jetcafe.org designates 205.147.26.23 as permitted sender) smtp.mailfrom=dave@jetcafe.org X-Spamd-Result: default: False [-1.30 / 15.00]; RCVD_TLS_ALL(0.00)[]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; FROM_HAS_DN(0.00)[]; RBL_DBL_DONT_QUERY_IPS(0.00)[205.147.26.23:from]; TO_MATCH_ENVRCPT_ALL(0.00)[]; R_SPF_ALLOW(-0.20)[+mx]; MIME_GOOD(-0.10)[text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-hackers@freebsd.org]; TO_DN_NONE(0.00)[]; RCPT_COUNT_ONE(0.00)[1]; SPAMHAUS_ZRD(0.00)[205.147.26.23:from:127.0.2.255]; DMARC_NA(0.00)[jetcafe.org]; NEURAL_SPAM_SHORT(1.00)[1.000]; NEURAL_HAM_LONG(-1.00)[-1.000]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:7397, ipnet:205.147.0.0/18, country:US]; RCVD_COUNT_TWO(0.00)[2]; MAILMAN_DEST(0.00)[freebsd-hackers] X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 06 Dec 2020 23:36:35 -0000 When I'm running FreeBSD on what amounts to a live DVD (no writable filesystems), I get this message: arc4random: no preloaded entropy cache I went looking in the source for this message and near enough to the message source found this troubling comment in sys/libkern/arc4random.c: /* * This is making the best of what may be an insecure * Situation. If the loader(8) did not have an entropy * stash from the previous shutdown to load, then we will * be improperly seeded. The answer is to make sure there * is an entropy stash at shutdown time. */ So security-wise, just how bad is it to be improperly seeded? If I cannot get a valid entropy stash at boot time, can I delay the need for it until I can get a writable filesystem up and running? Thanks in advance for any cogent replies. -- Dave Hayes - Consultant - LA CA, USA - dave@dream-tech.com >>>> *The opinions expressed above are entirely my own* <<<< The person who first said "There is no smoke without fire" may have been describing the state of the technology at the time it was said, not enunciating a truth.