Re: Re: Improving mt_rand() seed <lauri.kentta@gmail.com>

Hi Tom, On Sun, Jan 22, 2017 at 1:26 AM, Tom Worster <fsb@thefb.org> wrote: > On 1/20/17 9:55 PM, Yasuo Ohgaki wrote: > >> CSPRNG failure is like BUS error, i.e. hardware error. CSPRNG shouldn't >> fail with healthy hardware/OS. >> > > One would like to think so but low entropy environments exist. The problem > may even be getting more widespread as embedded systems become more > widespread. > Could you give some examples? I'm not sure what kind of IoT devices/OS that support PHP do not have CSPRNG. OSes can provide CSPRNG w/o hardware based RNG. Security on IoT matters a lot, especially for IoT that supports PHP. CSPRNG features are in PHP core already. Secure PHP scripts wouldn't work anyway on such devices anyway. e.g. generating nonce or like. > Therefore, we should not add poor fallback >> code for it. >> > > I don't see a need or value in breaking programs that previously worked > properly in the absence of a functioning system CSPRNG. > > mt_rand() and uniqid() were not secure before so seed them securely if you > can otherwise let them work as they did before. > Issues are - Current mt_rand() is not fully exploited. It wastes more than 99% of its random cycle. - Current uniqid()'s entropy is extremely poor and there is fair chances for collisions. Question is - Are we going to keep these poor behaviors as PHP spec/standard forever or not. Regards, -- Yasuo Ohgaki yohgaki@ohgaki.net