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 3153646B6D for ; Mon, 3 Jul 2023 20:57:35 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 8BED968C5AB; Mon, 3 Jul 2023 23:57:33 +0300 (EEST) Received: from iq.passwd.hu (iq.passwd.hu [217.27.212.140]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 7EB1C68C529 for ; Mon, 3 Jul 2023 23:57:27 +0300 (EEST) Received: from localhost (localhost [127.0.0.1]) by iq.passwd.hu (Postfix) with ESMTP id AFC5CE8BD6 for ; Mon, 3 Jul 2023 22:54:43 +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 aLHeLsdLm4mg for ; Mon, 3 Jul 2023 22:54:41 +0200 (CEST) Received: from iq (iq [217.27.212.140]) by iq.passwd.hu (Postfix) with ESMTPS id 77E05E8BA3 for ; Mon, 3 Jul 2023 22:54:41 +0200 (CEST) Date: Mon, 3 Jul 2023 22:54:41 +0200 (CEST) From: Marton Balint To: FFmpeg development discussions and patches In-Reply-To: <168841533190.542.8113031316523716543@lain.khirnov.net> Message-ID: <4b0740-7b32-415b-47af-3199463854b@passwd.hu> References: <20230702193010.11654-1-cus@passwd.hu> <54fe8899-d250-8d62-1157-621deb546040@gmail.com> <168841533190.542.8113031316523716543@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 James Almer (2023-07-03 21:33:04) >> On 7/2/2023 4:30 PM, Marton Balint wrote: >>> It should be OK to use av_get_random_seed() to generate the key instead of >>> using openSSL/Gcrypt functions. This removes the hard dependancy of those libs >>> for key generation functionality. >>> >>> Fixes ticket #10441. >>> >>> Signed-off-by: Marton Balint >>> --- >>> libavformat/hlsenc.c | 18 ++++++++---------- >>> 1 file changed, 8 insertions(+), 10 deletions(-) >>> >>> diff --git a/libavformat/hlsenc.c b/libavformat/hlsenc.c >>> index 1e0848ce3d..0b22c71186 100644 >>> --- a/libavformat/hlsenc.c >>> +++ b/libavformat/hlsenc.c >>> @@ -40,6 +40,7 @@ >>> #include "libavutil/intreadwrite.h" >>> #include "libavutil/opt.h" >>> #include "libavutil/log.h" >>> +#include "libavutil/random_seed.h" >>> #include "libavutil/time.h" >>> #include "libavutil/time_internal.h" >>> >>> @@ -710,18 +711,18 @@ fail: >>> return ret; >>> } >>> >>> -static int randomize(uint8_t *buf, int len) >>> +static void randomize(uint8_t *buf, int len) >>> { >>> #if CONFIG_GCRYPT >>> gcry_randomize(buf, len, GCRY_VERY_STRONG_RANDOM); >>> - return 0; >>> + return; >>> #elif CONFIG_OPENSSL >>> if (RAND_bytes(buf, len)) >>> - return 0; >>> -#else >>> - return AVERROR(ENOSYS); >>> + return; >>> #endif >>> - return AVERROR(EINVAL); >>> + av_assert0(len % 4 == 0); >>> + for (int i = 0; i < len; i += 4) >>> + AV_WB32(buf + i, av_get_random_seed()); >> >> Maybe instead use a PRNG, like the following: >> >> AVLFG c; >> av_lfg_init(&c, av_get_random_seed()); >> for (int i = 0; i < len; i += 4) >> AV_WB32(buf + i, av_lfg_get(&c)); > > We really REALLY should not be taking any shortcuts when generating > keys. > > Ideally we shouldn't be generating them ourselves in the first place, as > we are not a crypto library. This patch seems like a step backward to > me. 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. You really think that these are significantly worse than OpenSSL/GCrypt, so it should not be allowed to fallback to? 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".