Generate random prime

[barryvdh]

Instead of letting the user pick a prime, why not find a random one with php? Or is that more insecure?

Something like this in the Spark command for example, when the prime is empty (Although random_int would be safer in PHP7)

protected function findRandomPrime()
{
    $min = 1e6;
    $max = 2147483647;
    for ($i=rand($min, $max); $i < $max; $i++) {
        if ($this->isPrime($i)) {
            return $i;
        }
    }
}

/**
 * From http://stackoverflow.com/a/16763365/444215
 * @param $num
 * @return bool
 */
protected function isPrime($num){
    /**
     * if the number is divisible by two, then it's not prime and it's no longer
     * needed to check other even numbers
     */
    if($num % 2 == 0) {
        return false;
    }
    /**
     * Checks the odd numbers. If any of them is a factor, then it returns false.
     * The sqrt can be an aproximation, hence just for the sake of
     * security, one rounds it to the next highest integer value.
     */
    for($i = 3; $i <= ceil(sqrt($num)); $i = $i + 2) {
        if($num % $i == 0)
            return false;
    }

    return true;
}

[barryvdh]

Replaced by #6