Question

I am trying to create a ‘confirmation code’ for every user account created on my website and storing it in the db along with their personal information. As you can see in the example below, I tried to generate a random string factoring in the time variable, however, the string is unneccessarily long.

I would like the string to be shorter than the one produced by md5 I was wondering if there is a relatively easy way to generate 10 digit (max) alphanumeric string that has an extremely low collision rate?

What I tried:

  md5(mt_rand(10000,99999).time() . '[e-mail]');

Output:

0dd6854dba19e70cfda0ab91595e0376

Answer 1

PHP provides the openssl_random_pseudo_bytes function that can be made to securely do what you want.

Do something like:

bin2hex(openssl_random_pseudo_bytes(5))

The above will give you something like e9d196aa14, for example.

Alternatively, just take the first 10 chars of your existing MD5 string.