Password Hashing PHP Class

PassHash.php

<?php

/**
 * Hashing user passwords
 * 
 * @author Ravi Tamada
 * @source http://www.androidhive.info/2014/01/how-to-create-rest-api-for-android-app-using-php-slim-and-mysql-day-23/
 */

class PassHash{
	
	// blowfish algo
	private static $algo = '$2a';
	// cost parameter
	private static $cost = '$10';

	// Creating hashing salt
	public static function unique_salt(){
		return substr( sha1(mt_rand()), 0, 22 );
	}

	/**
	 * Generate password hash
	 */
	public static function hash($password){
		return crypt( $password, self::$algo . self::$cost . '$' . self::unique_salt() );
	} 

	/**
	 * Compare password against a hash
	 */
	public static function check_password($hash, $password){
		$full_salt = substr($hash, 0, 29);
		$new_hash = crypt($password, $full_salt);

		return ($hash == $new_hash);
	}
}