Bug #68959 [Opn->Nab]: limit rand() function

Edit report at https://bugs.php.net/bug.php?id=68959&edit=1 ID: 68959 Updated by: nikic@php.net Reported by: peter dot mlich at volny dot cz Summary: limit rand() function -Status: Open +Status: Not a bug Type: Bug Package: *General Issues Operating System: win PHP Version: 5.5.21 Block user comment: N Private report: N New Comment: rand() exposes the libc rand source and Windows is notable for providing a very weak linear congruential generator. If you want to get stronger random numbers, use mt_rand(), which is based on MT19937. Note that they aren't cryptographic in any case. Previous Comments: ------------------------------------------------------------------------ [2015-01-30 09:38:03] peter dot mlich at volny dot cz Description: ------------ After about 32000 function rand() repeating number (or zero?) as pattern. Array can be easy compressed by gzip. If you understand about compression, this is critical bug. I test array with 10.000 numbers, gzip compress to 33%. Other script with no rand() with read from file compress about 100.5% (my compress script about 95%). I cant use random data generator, if repeating as pattern which can easy compress with php-gzip. php 5.3.5, wamp server 2.1 php 5.5.12, wamp server 2.5 Test script: --------------- $max = 32000; $max = 100000; $arr = array(); for ($i=0;$i<$max;$i++) { $arr[$i] = rand(0,255); } return $arr; ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=68959&edit=1