Hash Collision with Random Key

[GB_001]

Hello, I created a system where emails get encrypted with a random key that gets stored in a database, what are the odds of the Hashes Colliding?

 

Part of the code:

 

function genRandomString($num) {    $length = $num;    $characters = '0123456789abcdefghijklmnopqrstuvwxyz';    $string = "";        for ($p = 0; $p < $length; $p++) {        $string .= $characters[mt_rand(0, strlen($characters))];    }    return $string;}$Key=genRandomString(10);$email_s=hash_hmac('ripemd160', $email, $Key);

 

 

Thankyou, GB.

[the182guy]

It's impossible to calculate the odds because the length of the random string is dynamic (passed in as an argument to the function). The longer the string, the longer the odds.

 

If you really want to test this then create a script which constantly calls your function and stores the results in a MySQL table, leave it running for some time to get a few thousand records....or more. Then do a SELECT DISTINCT query on the table and if the distinct row count matches the actual row count then you know they are all unique.

 

Another option here is to use uniq() and then hash() it using your preferred algo.