Path: csiph.com!3.us.feeder.erje.net!feeder.erje.net!news.linkpendium.com!news.linkpendium.com!panix!usenet.stanford.edu!not-for-mail From: Ole Tange Newsgroups: gnu.bash.bug Subject: Re: $RANDOM not Cryptographically secure pseudorandom number generator Date: Wed, 2 Jan 2019 02:29:24 +0100 Lines: 36 Approved: bug-bash@gnu.org Message-ID: References: <868cc2da-cf67-298f-4640-ab1afcf857e0@case.edu> <4bc5800d-0dfb-17a5-0b20-9f4bef5a60b6@case.edu> <8d46616b-7618-be59-3651-1a01bc3bf7e6@case.edu> NNTP-Posting-Host: lists.gnu.org Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" X-Trace: usenet.stanford.edu 1546392582 5500 208.118.235.17 (2 Jan 2019 01:29:42 GMT) X-Complaints-To: action@cs.stanford.edu Cc: Eduardo Bustamante , bug-bash To: Chet Ramey Envelope-to: bug-bash@gnu.org X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=cfFOg68sshkuBwH5MhctMHMN8vOWWpM6T1ckEUrjX1I=; b=AyRFOcc+Qo1A750W6oZ7lXvFnH48WI0V8VhSLFOq2k2TPJ7dtezEfIklizv4PblrRB 5dpkRYYu3Mx03djdWP5oGgdgPDBSOOHgIYHj9+s2tLM1PZGCuC1ZirQtAfPxt30f7Sts hzNuo2G23E/3gKGWOog88H1X1uOYZ+yPnXrSP8siv7YEpRJmOZglj3rsWUlN2LAamL29 4ejvY5Xc+tlQs3AbPoPEaIhN/cHGdldKf4s9Q7afCqg1K/8PLp6Nduiu1DRE79mLjIVd KU2lX2jfGfXmrGQiSuyf6wbl2mQQ+paHhUm5uW6tmZlpdgIzZOdFavzey2aNxrrCqpEp 6LzA== X-Gm-Message-State: AA+aEWaQHiU7Xp7sNSEHk59QCYd5R9h60pvqZaub4fExp/ZKIINf7f+0 Qj7tZ59/Q5/PJajkBjzpcPDHfMhoXX97ipqIEMk= X-Google-Smtp-Source: AFSGD/UgIZcX+HlloOEM5SNiOgIQVST4mtpIbA9fCkZpuj7v58pK/PMZ5NzS+a3i+g9bJwpy8loiXir9oIKK6RT/4Wo= X-Received: by 2002:a02:708e:: with SMTP id f136mr27981024jac.118.1546392576889; Tue, 01 Jan 2019 17:29:36 -0800 (PST) In-Reply-To: <8d46616b-7618-be59-3651-1a01bc3bf7e6@case.edu> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.85.166.179 X-BeenThere: bug-bash@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: Bug reports for the GNU Bourne Again SHell List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Xref: csiph.com gnu.bash.bug:15027 On Mon, Dec 31, 2018 at 8:12 PM Chet Ramey wrote: : > Thanks for the patch. I'll take a look after I release bash-5.0. One > question: can you reproduce the same random sequence by using the same > seed? That's for backwards compatibility, even if the sequences themselves > differ. Yes. Seeding with a value will give the same sequence: $ RANDOM=4; echo $RANDOM $RANDOM 21584 22135 $ RANDOM=4; echo $RANDOM $RANDOM 21584 22135 For backwards compatibility integers are supported, but they are really parsed as strings. Strings make it easier to seed with more than 64-bits: RANDOM=`cat GPLv3.txt` So these give the same value on 4.4.23, but differs with the patch applied: RANDOM=$(echo 2^64 | bc );echo $RANDOM RANDOM=$(echo 2^65 | bc );echo $RANDOM RANDOM="foo"; echo $RANDOM RANDOM="bar"; echo $RANDOM RANDOM=2; echo $RANDOM RANDOM=" 2.0"; echo $RANDOM RANDOM=" 2.0noise"; echo $RANDOM /Ole