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To: Yasuo Ohgaki <yohgaki@ohgaki.net>
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Cc: PHP internals <internals@lists.php.net>
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Date: Sat, 12 May 2018 17:03:05 -0700
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Subject: Re: [PHP-DEV] [RFC] Deprecation of uniqid()
From: alice@librelamp.com (Alice Wonder)

On 05/12/2018 03:46 PM, Yasuo Ohgaki wrote:
> On Fri, May 11, 2018 at 9:34 PM, Alice Wonder <alice@librelamp.com
> <mailto:alice@librelamp.com>> wrote:
>
>     slightly better if block
>
>     if($more_entropy) {
>       sodium_increment($nonce);
>       $x = hexdec(substr(bin2hex($nonce),0,12));
>       $return = $return . substr($x, 2, 1) . '.' . substr($x, -8);
>     }
>
>     Obvious patterns in the "more entropy" but the output in only
>     suppose to be unique, not random.
>
>
> The most important issue in current uniqid() is it could have duplicate
> even with $more_entropy=true, since it has
>
> <time_part> + <random based on time>
>
> structure.
> System time could be adjusted backwards by ntp, etc.
>
> However changing output by default as follows is enough for it.
>
> <time_part> + <random based on CSPRNG>

+ random though is expensive if you have to create many at a time, using 
an increment when called multiple times on same page requests results in 
pattern but is less expensive.

So if predictable is okay that's better IMHO and often predictable (with 
a pattern) is okay.

random based on time isn't necessary.

<time part> + <nonce>

should be sufficient.