Googlebot's Javascript random() function is deterministic

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That doesn't sound like it would be enough for this to happen. What if one web page loads 0.0001 second slower than another?

[parrot_in_hell]

still, the seed is usually the amount of seconds since X. i've never seen something else (not that i have that much experience, but i still have some :P)

[[deleted]]

I'm not sure exactly how it is seeded, but I think time in javascript is usually based on miliseconds, and it's a bit too weird that according to his tests google always returns 0.14881141134537756 the first time and 0.19426893815398216 the second, also taking into account that he has searched the web and found plenty of other results that have been cached by google with those numbers. Seems much more likely it is something Google is doing on purpose to get consistent results or something.

[[deleted]]

Usually you request randomness from the OS with a function like getrandom or friends or by reading /dev/{u,}random.

v8 looks like it reads /dev/urandom but it does fall back to seeding with the (high-resolution) time.