Laravel Rule encouraging Stanford's Password Policy

Password.php

<?php

namespace App\Rules;

use Illuminate\Validation\Rules\Password as Rule;

/**
 * A password rule for Laravel based on Stanford's best practices.
 * https://uit.stanford.edu/service/accounts/passwords
 *
 * 8-11: mixed case letters, numbers, & symbols
 * 12-15: mixed case letters & numbers
 * 16-19: mixed case letters
 * 20+: no restrictions
 *
 * It must not be equal to your current password, previous passwords, SUNet ID, or password reset answer
 * It must not be a single word that appears in the dictionary (English or non-English)
 * It must be composed only of characters in the Roman alphabet, numbers, or symbols on the US keyboard. Examples include characters such as # $ % ! @.
 */
class Password extends Rule
{
    /**
     * Create a new rule instance.
     *
     * @return void
     */
    public function __construct(int $min = 8)
    {
		parent::__construct($min);
        //
    }

	/**
	 * Determine if the validation rule passes.
	 *
	 * @param  string  $attribute
	 * @param  mixed  $value
	 * @return bool
	 */
	public function passes($attribute, $value)
	{
		$length = strlen($value);

		/**
		 * No restrictions.
		 */
		$this->mixedCase = false;
		$this->letters = false;
		$this->numbers = false;
		$this->symbols = false;
		$this->uncompromised = false;

		if ($length < 20) {
			$this->mixedCase = true;
		}
		if ($length < 16) {
			$this->numbers = true;
		}
		if ($length < 11) {
			$this->symbols = true;
		}

		return parent::passes($attribute, $value);
	}
}