Is the str::random() function in Laravel reliable for short URL?

Question

I'm trying to create a simple url shortener in my Laravel project. I want to use only lowercase and uppercase letters and numbers as short url addresses. (For example: sD7hY6g) Is there a possibility that "Str::random()" function under "Illuminate\Support\Str" class in Laravel returns anything other than these characters? Can I trust this function or do I need to create my own custom function?

(In addition, whichever function I use, I check whether the code is already in the database before recording.)

Thank you to everyone who answered in advance.

Answer 1

Should you trust Str::random() to always return an alpha-numeric string? Yes.

The function normalizes its output by encoding to base 64 number. The 64 symbols that represent a base 64 number are ABCDEFGHIJKLMNOPQRSTUVWXYVabcdefghijklmnopqrstuvwxyz0123456789+\ and = for padding.

The function also replaces \+= to empty (white spaces), meaning that the only possible output for Str::random() are amongst ABCDEFGHIJKLMNOPQRSTUVWXYVabcdefghijklmnopqrstuvwxyz0123456789.

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Laravel 5+'s Illuminate\Support\Str@random

public static function random($length = 16)
{
    $string = '';

    while (($len = strlen($string)) < $length) {
        $size = $length - $len;
        
        $bytes = random_bytes($size);
        
        $string .= substr(str_replace(['/', '+', '='], '', base64_encode($bytes)), 0, $size);
    }

    return $string;
}