On Fri, 31 Jan 2025, Michael Niedermayer wrote:
diff --git a/libavutil/random_seed.c b/libavutil/random_seed.c index 8a4e4f1fc0..8f969060a0 100644 --- a/libavutil/random_seed.c +++ b/libavutil/random_seed.c @@ -83,6 +83,7 @@ static uint32_t get_generic_seed(void) static uint32_t buffer[512] = { 0 }; unsigned char digest[20]; uint64_t last_i = i; + int cur_iters = 0;av_assert0(sizeof(tmp) >= av_sha_size); @@ -98,11 +99,13 @@ static uint32_t get_generic_seed(void) for (;;) { clock_t t = clock(); - if (last_t + 2*last_td + (CLOCKS_PER_SEC > 1000) >= t) { + if (last_t + 2*last_td + (CLOCKS_PER_SEC > 1000) >= t && cur_iters < 128) { last_td = t - last_t; buffer[i & 511] = 1664525*buffer[i & 511] + 1013904223 + (last_td % 3294638521U); + cur_iters++; } else { last_td = t - last_t; + cur_iters = 0;Iam concerned this could negatively impact entropy The "else" should be run when a interrupt/task switch occured. If that doesnt occur in 128 iterations that doesnt gurantee the entropy has increased. If there are only 0 and 1, ideally we should look at the distribution and go to the else when the pattern differs from the past / has some signs of randomness
Ok, I've somewhat tried to implement this, please take a look. // Martin _______________________________________________ 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".
