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 B7E3446B50 for ; Mon, 3 Jul 2023 20:23:23 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id E40EE68C5AC; Mon, 3 Jul 2023 23:23:20 +0300 (EEST) Received: from iq.passwd.hu (iq.passwd.hu [217.27.212.140]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 1DC0D68C54B for ; Mon, 3 Jul 2023 23:23:15 +0300 (EEST) Received: from localhost (localhost [127.0.0.1]) by iq.passwd.hu (Postfix) with ESMTP id 0AB52E8BD6 for ; Mon, 3 Jul 2023 22:20:32 +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 klhQ0Nqw1QaF for ; Mon, 3 Jul 2023 22:20:29 +0200 (CEST) Received: from iq (iq [217.27.212.140]) by iq.passwd.hu (Postfix) with ESMTPS id 47C41E8BA3 for ; Mon, 3 Jul 2023 22:20:29 +0200 (CEST) Date: Mon, 3 Jul 2023 22:20:29 +0200 (CEST) From: Marton Balint To: FFmpeg development discussions and patches In-Reply-To: <54fe8899-d250-8d62-1157-621deb546040@gmail.com> Message-ID: <7949b7-f9a-d211-66e5-f17bd264459@passwd.hu> References: <20230702193010.11654-1-cus@passwd.hu> <54fe8899-d250-8d62-1157-621deb546040@gmail.com> 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, James Almer wrote: > 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)); If randomize() were to be used for arbitrary lengths, I'd agree, but here it is only used for key generation (only 128-bit keys in the current code), so I think av_get_random_seed() for the whole keysize is fine, and more secure. 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".