Quoting James Almer (2023-07-04 16:37:03) > On 7/4/2023 2:54 AM, Anton Khirnov wrote: > > Quoting Michael Niedermayer (2023-07-04 01:50:57) > >> On Mon, Jul 03, 2023 at 11:09:54PM +0200, 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() > >>> 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. > >>> > >>> 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. > >> > >> "guarantees cryptographically secure randomness" ? > >> If one defined "cryptographically secure" as "not broken publically as of > >> today" > >> > >> Iam saying that as i think "guarantees" can be misleading in what it means > > > > I feel your snark is very much misplaced. > > > > I recall way more instances of broken crypto caused by overconfident > > non-experts with an attitude like yours ("those silly crypto libraries, > > broken all the time, how hard can it be really") than by actual > > vulnerabilities in actual crypto libraries. > > > > In fact the highest-profile break I remember (Debian key entropy bug) > > was caused precisely by non-experts fiddling with code they did not > > understand. > > Maybe the gcrypt and openssl API calls used here can instead be moved to > av_get_random_seed(), which would reduce (or outright remove) the cases > /dev/random or get_generic_seed() are called and result in essentially
I see nothing wrong with using /dev/random, it's probably the most trustworthy source on most machines. Though on linux it's probably even better to use getrandom() where available. -- Anton Khirnov _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".