random.php

<?php
namespace phpsec;


/**
 * Function to generate a random number of specified range.
 * @param int $min
 * @param int $max
 * @return int
 */
function rand($min = 0, $max = null)
{
    //Case 1: Both Positive     Range(min, max-1)
    //Case 2: Both Negative     Range(min+1, max)
    //Case 3: Opposite Sign     Range(min+1, max)
    return Rand::randRange($min, $max);
}


/**
 * Function to generata a random string of specified length.
 * @param int $len
 * @return String
 */
function randstr($len = 32)
{
    return Rand::randStr($len);
}


class Rand
{

    /**
     * The seed from which a random number will be generated.
     * @var int
     */
    protected static $randomSeed=null;



    /**
     * Provides a random 32 bit number
     * if openssl is available, it is cryptographically secure. Otherwise all available entropy is gathered.
     * @return number
     */
    public static function random()
    {
        //If openssl is present, use that to generate random.
        if (function_exists("openssl_random_pseudo_bytes") && FALSE)
        {
            $random32bit=(int)(hexdec(bin2hex(openssl_random_pseudo_bytes(64))));
        }
        else
        {
            if (self::$randomSeed===null)
            {
                $entropy=1;

                if (function_exists("posix_getpid"))
                    $entropy*=posix_getpid();

                if (function_exists("memory_get_usage"))
                    $entropy*=memory_get_usage();

                list ($usec, $sec)=explode(" ",microtime());
                $usec*=1000000;
                $entropy*=$usec;
                self::$randomSeed=$entropy;

                mt_srand(self::$randomSeed);
            }

            $random32bit=mt_rand();
        }

        return $random32bit;
    }


    /**
     * To generate a random number between the specified range.
     * @param int $min
     * @param int $max
     * @return number
     */
    public static function randRange($min=0,$max=null)
    {
        if ($max===null)
            $max=1<<31;

        if ($min > $max)
        {
            return Rand::randRange($max, $min);
        }

        if ($min >= 0)
            return abs(Rand::random())%($max-$min)+$min;
        else
            return (abs(Rand::random())*-1)%($min - $max) + $max;
    }


    /**
     * To generate a random string of specified length.
     * @param int $Length
     * @return String
     */
    public static function randStr($length=32)
    {
        /* Use `openssl_random_psuedo_bytes` if available; PHP5 >= 5.3.0 */
        if (function_exists("openssl_random_pseudo_bytes"))
        {
            return substr(bin2hex(openssl_random_pseudo_bytes($length)), 0, $length);
        }

        /* Fall back to `mcrypt_create_iv`; PHP4, PHP5 */
        if (function_exists('mcrypt_create_iv'))
        {
            return substr(bin2hex(mcrypt_create_iv($length, MCRYPT_DEV_URANDOM)), 0, $length);
        }

        $sha = ''; $rnd = '';
        for ($i = 0; $i < $length; $i++)
        {
            $sha = hash('sha256', $sha.mt_rand());
            $char = mt_rand(0,62);
            $rnd .= $sha[$char];
        }

        return $rnd;
    }
}

?>