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Date: Mon, 14 Feb 2022 12:40:22 +0100
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To: Go Kudo <g-kudo@colopl.co.jp>, internals@lists.php.net
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Subject: Re: [PHP-DEV] [RFC] [Under Discussion] Random Extension 4.0
From: timwolla@bastelstu.be (=?UTF-8?Q?Tim_D=c3=bcsterhus?=)

Hi

On 2/14/22 12:11, Go Kudo wrote:
> The refreshed RFC and implementation are available at the following URL:
> 
> https://wiki.php.net/rfc/rng_extension
> https://github.com/php/php-src/pull/8094
> 
> If there are no specific comments, I would like to start voting as soon as
> the two-week pre-announcement phase is over.

1) XorShift128+ has a 128 Bit internal state, but takes an integer seed 
within the constructor. Thus only 64 Bits of seed can be provided.

Maybe the seed parameter should be a 16-byte string instead? 
Initializing the generator with a completely random seed would then be:

new XorShift128Plus(\random_bytes(16));

instead of the much more complicated:

new XorShift128Plus(\random_int(\PHP_INT_MIN, \PHP_INT_MAX));

Perhaps the following API would be even clearer:

XorShift128Plus::fromSeed(\random_bytes(16));
XorShift128Plus::fromGenerator(new Secure()); // Takes 16 bytes from the 
given generator.

2) I would adjust the 'Randomizer' to use the 'Secure' generator as a 
safe default. If absolute performance or a reproducible sequence is 
required then one can use a custom generator, but the default will be 
the secure CSPRNG, making it harder to misuse.

3) The RFC is inconsistent in the example code. Is it 'stringShuffle' or 
'shuffleString'?

4) The RFC should document the 'NumberGenerator' interface. Specifically 
I'm interested in the return type of the 'generate' method. Does it 
return bytes or integers? Is it legal to implement the interface in 
userland code?

Best regards
Tim Düsterhus