From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org [79.124.17.100]) by master.gitmailbox.com (Postfix) with ESMTP id B459D46B6F for ; Mon, 3 Jul 2023 21:55:44 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 403C168C532; Tue, 4 Jul 2023 00:55:41 +0300 (EEST) Received: from iq.passwd.hu (iq.passwd.hu [217.27.212.140]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 5578A68C532 for ; Tue, 4 Jul 2023 00:55:35 +0300 (EEST) Received: from localhost (localhost [127.0.0.1]) by iq.passwd.hu (Postfix) with ESMTP id F1845E73A4 for ; Mon, 3 Jul 2023 23:52:51 +0200 (CEST) X-Virus-Scanned: amavisd-new at passwd.hu Received: from iq.passwd.hu ([127.0.0.1]) by localhost (iq.passwd.hu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id jZIWwykd8vUj for ; Mon, 3 Jul 2023 23:52:46 +0200 (CEST) Received: from iq (iq [217.27.212.140]) by iq.passwd.hu (Postfix) with ESMTPS id 980EFE55D1 for ; Mon, 3 Jul 2023 23:52:46 +0200 (CEST) Date: Mon, 3 Jul 2023 23:52:46 +0200 (CEST) From: Marton Balint To: FFmpeg development discussions and patches In-Reply-To: <168841859463.9711.12513000520212201640@lain.khirnov.net> Message-ID: References: <20230702193010.11654-1-cus@passwd.hu> <54fe8899-d250-8d62-1157-621deb546040@gmail.com> <168841533190.542.8113031316523716543@lain.khirnov.net> <4b0740-7b32-415b-47af-3199463854b@passwd.hu> <168841859463.9711.12513000520212201640@lain.khirnov.net> MIME-Version: 1.0 Subject: Re: [FFmpeg-devel] [PATCH 1/2] avformat/hlsenc: fall back to av_get_random_seed() when generating AES128 key X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: On Mon, 3 Jul 2023, Anton Khirnov wrote: > Quoting Marton Balint (2023-07-03 22:54:41) >> On Mon, 3 Jul 2023, Anton Khirnov wrote: >> My patch use av_get_random_seed() which uses what the underlying OS >> provides, BCrypt for Windows, /dev/urandom for Linux, arc4random() for >> BSD/Mac. > > IOW it's a jungle of various paths, some of which are not guaranteed to > be cryptographically secure. I see no such guarantees for arc4random() It depends on OS and version most likely. > from a brief web search, and the fallback get_generic_seed() certainly > is not either. > Granted it's only used on obscure architectures, but > still. I am no expert on the subject, but even the generic code seems reasonably secure. It gathers entropy, it uses a crypto hash to get the output. And as you said, even that only used for obscure cases. > > The doxy even says >> This function tries to provide a good seed at a best effort bases. > >> You really think that these are significantly worse than >> OpenSSL/GCrypt, so it should not be allowed to fallback to? > > I think we should be using cryptographically secure PRNG for generating > encryption keys, or fail when they are not available. If you want to get > rid of the openssl dependency, IMO the best solution is a new > int av_random(uint8_t* buf, size_t len); > that guarantees either cryptographically secure randomness or an error. Sorry, seems a bit overdesign for me, so I won't be pursuing this further. Regards, Marton _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".