Remove seeding in random number generator #9535
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This is done for the following reasons: * Code clean-up. From https://secure.php.net/manual/en/function.mt-srand.php: > Note: There is no need to seed the random number generator with srand() or mt_srand() as this is done automatically. * Re-seeding of PRNGs makes them more predictable. E.g., the `microtime()` which is used for the seeding: * On Windows (before Win8): seems to return 0, according to https://stackoverflow.com/questions/18889244/php-5-5-on-windows-microtime-behavior. * On other OSes: The current time is easily guessable, with the "microseconds" part brute-forcible.
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The one test failure does not seem to be related to this change:
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Thx for the PR! See http://us2.php.net/manual/en/function.mt-srand.php
Therefore LGTM 👍 FYI: Method was initially added in 2b9182d#diff-805dc290a8e0e0e5b40c289a532e3297R760 and it seems not be related for any special reason. |
tsteur
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This is done for the following reasons:
Code clean-up. From https://secure.php.net/manual/en/function.mt-srand.php:
Re-seeding of a PRNG makes it more predictable. E.g., the
microtime()which is used for the seeding:Because a PRNG's output sequence is equal for the same seed, the re-seeding could make more predictable not only the output of the
Common::getRandomString()function modified here, but also subsequent calls ofmt_rand(), which is currently used also in security-related context (see Using secure random numbers #9473).E.g. (not tested), a user could:
Common::getRandomString()in https://github.com/piwik/piwik/blob/2.16.0-b2/plugins/Monolog/Handler/WebNotificationHandler.php#L46Note: The only other
rand()/mt_rand()(re-)seeding is in the "Faker" library in https://github.com/piwik/plugin-VisitorGenerator/blob/1.2.2/libs/Faker/Faker/Generator.php#L137, but it doesn't seem to be used at the moment - see https://github.com/piwik/plugin-VisitorGenerator/blob/1.2.2/libs/Faker/readme.md#seeding-the-generator for its use case.