PHP 64 bit Random Number

Question

does anyone know a simple way to generate a random 64 bit number using PHP? It would be best if it doesn't rely on any extensions if possible.

Maybe this link can help - http://stackoverflow.com/questions/4523343/how-do-you-generate-a-random-number-over-the-32bit-limit-in-php — lethalMango, Jun 08 '11 at 21:34

score 4 · Answer 1 · answered Jun 08 '11 at 21:35

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Fetch 8 random bytes from /dev/urandom or some equivalent source.

answered Jun 08 '11 at 21:35

Denis de Bernardy

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how? could use a little more on this answer – Ascherer Jun 08 '11 at 21:56
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It's a file... `$fp = fopen('/dev/urandom'); fread($fp, 8); fclose($fp);` – Denis de Bernardy Jun 08 '11 at 22:09
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or try: `$rnd = file_get_contents('/dev/urandom', false, null, 0, 8);` – hakre Jun 09 '11 at 02:42

score 3 · Answer 2 · answered Jun 08 '11 at 21:36

3

This?

rand(0, 18446744073709551615)

From the php documentation

On some platforms (such as Windows), getrandmax() is only 32768. If you require a range larger than 32768, specifying min and max will allow you to create a range larger than this, or consider using mt_rand() instead.

answered Jun 08 '11 at 21:36

Eric

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This works for `mt_rand` too, but it only returns values different from 0 for smaller numbers than the one given above. – likeitlikeit Mar 27 '14 at 11:52
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This gives "Warning: rand() expects parameter 2 to be integer, float given in - on line 1" on PHP 7. – Janus Troelsen Jul 24 '15 at 18:15
Also, the results may not be distributed evenly: https://bugs.php.net/bug.php?id=63174#1437000589 – Janus Troelsen Jul 24 '15 at 18:16

score 3 · Accepted Answer · answered Jun 08 '11 at 21:42

3

Generate a bunch of smaller (16 bits) random numbers using mt_rand and combine them. This approach is also used in this UUID example on php.net.

answered Jun 08 '11 at 21:42

GolezTrol

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That seemed to work. Although, when I converted it using `base_convert` it was too large? I think it might be a problem with the precision of that function? – Ewan Heming Jun 10 '11 at 07:21

score 1 · Answer 4 · answered Sep 19 '16 at 11:13

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$rand64bit = rand() << 32 | rand();

answered Sep 19 '16 at 11:13

muto

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PHP 64 bit Random Number

4 Answers4