Generate a random password in PHP

Question

I want to generate a random password with PHP, to later send it to a user that registers. How can I achieve this best? I already tried to work with rand function, but I doesn't get it working. Best would be a possibility to have a function doing that for me, so I just need to call something like

$pw = generatePW();

Thank you for your help.

Ok, in terms of password security, it's generally not a good idea to send a password over email in plaintext. — hRdCoder, Oct 14 '15 at 19:38
Okay... well it only should be a one time password to login once and then change it (for easy mail confirmation) — , Oct 14 '15 at 19:40

nameless · Accepted Answer · 2015-10-14T19:38:59.140

-2

You can easily achieve this with the following function:

function random_string($length)
{
   $string = "";
   $chars = "abcdefghijklmanopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
   $size = strlen($chars);
   for ($i = 0; $i < $length; $i++) {
       $string .= $chars[rand(0, $size - 1)];
   }
   return $string; 
}

Here you first generate an empty string, then you define a string with all chars you want, you could also add # or ? or whatever you want. After you also counted the numbers of chars you can start with filling your new string. You just use a for-loop to do this. Everytime the loopcontent is called, there is one random char (from your $char) added to your empty string.

You use this function (for example if you want to store your random password in a variable) by simply typing:

$password = rand_string(15) //the number specified in brackets is the amount of characters in your password

Let me know if you're experiencing any issues.

edited Oct 14 '15 at 19:38

answered Oct 14 '15 at 19:34

nameless

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You never set `$string`. Return '' on every call, maybe meant `$string .=`? – chris85 Oct 14 '15 at 19:36
of course, updated that, thanks for the hint – nameless Oct 14 '15 at 19:39
1

This works for my purpose, thank you. But I'll think about sending an activation link instead of a password... – Oct 14 '15 at 19:44
1

Ewww. Don't use `rand()` for passwords, use [`random_int()`](https://secure.php.net/random_int) instead. – Scott Arciszewski Oct 21 '15 at 15:55

Generate a random password in PHP

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