[wp-trac] [WordPress Trac] #59239: wp_generate_uuid4 collisions

[WordPress Trac]

#59239: wp_generate_uuid4 collisions
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 Reporter:  joppuyo       |       Owner:  (none)
     Type:  defect (bug)  |      Status:  new
 Priority:  normal        |   Milestone:  7.0
Component:  General       |     Version:
 Severity:  normal        |  Resolution:
 Keywords:  has-patch     |     Focuses:
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Comment (by joppuyo):

 I created this ticket too because I observed some collisions when
 generating UUIDs with  wp_generate_uuid4().
 [https://www.php.net/manual/en/function.mt-srand.php According to PHP
 documentation], after 80,000 iterations the chance of a collision is 50%.
 I tested this myself by generating UUIDs using this function in a loop and
 after few minutes I managed to generate a collision around 80,000
 iterations.

 It seems like wp_rand() is a wrapper around random_int() and it only uses
 a fallback if the random_int() throws an exception (no random source
 available) or the function is not available. As it was added in PHP 7.0
 that's probably not relevant in current WordPress versions as they don't
 support PHP 5 any longer.

 I think it could be possible to just use random_int() directly if
 wp_rand() is not available. If that's too much duplicate code it might be
 possible to drop wp_rand() completely so the function works without the
 dependency on pluggable functions being loaded.

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Ticket URL: <https://core.trac.wordpress.org/ticket/59239#comment:5>
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