random_bytes

(PHP 7, PHP 8)

random_bytes — Generates cryptographically secure pseudo-random bytes

说明

random_bytes(int $length): string

Generates an arbitrary length string of cryptographic random bytes that are suitable for cryptographic use, such as when generating salts, keys or initialization vectors.

The sources of randomness used for this function are as follows:

On Windows, » CryptGenRandom() will always be used. As of PHP 7.2.0, the » CNG-API will always be used instead.
On Linux, the » getrandom(2) syscall will be used if available.
On other platforms, /dev/urandom will be used.
If none of the aforementioned sources are available, then an Exception will be thrown.

注意: Although this function was added to PHP in PHP 7.0, a » userland implementation is available for PHP 5.2 to 5.6, inclusive.

参数

length: The length of the random string that should be returned in bytes.

返回值

Returns a string containing the requested number of cryptographically secure random bytes.

错误／异常

If an appropriate source of randomness cannot be found, an Exception will be thrown.
If invalid parameters are given, a TypeError will be thrown.
If an invalid length of bytes is given, an Error will be thrown.

范例

示例 #1 random_bytes() example


<?php
$bytes = random_bytes(5);
var_dump(bin2hex($bytes));
?>

以上例程的输出类似于：

string(10) "385e33f741"

参见

random_int() - Generates cryptographically secure pseudo-random integers
openssl_random_pseudo_bytes() - 生成一个伪随机字节串
bin2hex() - 函数把包含数据的二进制字符串转换为十六进制值

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User Contributed Notes 7 notes

down

akam at akameng dot com ¶

6 years ago


I used below function to create random token, and also a salt from the token. I used it in my application to prevent CSRF attack.

<?php
function RandomToken($length = 32){
    if(!isset($length) || intval($length) <= 8 ){
      $length = 32;
    }
    if (function_exists('random_bytes')) {
        return bin2hex(random_bytes($length));
    }
    if (function_exists('mcrypt_create_iv')) {
        return bin2hex(mcrypt_create_iv($length, MCRYPT_DEV_URANDOM));
    } 
    if (function_exists('openssl_random_pseudo_bytes')) {
        return bin2hex(openssl_random_pseudo_bytes($length));
    }
}

function Salt(){
    return substr(strtr(base64_encode(hex2bin(RandomToken(32))), '+', '.'), 0, 44);
}

echo (RandomToken());
echo "\n";
echo Salt();
echo "\n";

/*
This function is same as above but its only used for debugging
*/
function RandomTokenDebug($length = 32){
    if(!isset($length) || intval($length) <= 8 ){
      $length = 32;
    }
    $randoms = array();
    if (function_exists('random_bytes')) {
        $randoms['random_bytes'] = bin2hex(random_bytes($length));
    }
    if (function_exists('mcrypt_create_iv')) {
        $randoms['mcrypt_create_iv'] = bin2hex(mcrypt_create_iv($length, MCRYPT_DEV_URANDOM));
    }
    if (function_exists('openssl_random_pseudo_bytes')) {
        $randoms['openssl_random_pseudo_bytes'] = bin2hex(openssl_random_pseudo_bytes($length));
    }
    
    return $randoms;
}
echo "\n";
print_r (RandomTokenDebug());

?>

down

ccbsschucko at gmail dot com ¶

4 years ago


<?php
    function str_rand(int $length = 64){ // 64 = 32
        $length = ($length < 4) ? 4 : $length;
        return bin2hex(random_bytes(($length-($length%2))/2));
    }
    
    var_dump(str_rand());
    // d6199909d0b5fdc22c9db625e4edf0d6da2b113b21878cde19e96f4afe69e714
?>

down

-5

Anonymous ¶

4 years ago


Simple php implementation of Blum Blum Shub.

<?php

$bbs = new BlumBlumShub(400);
var_dump(bin2hex($bbs->getRandomPseudoBytes(32)));
// out like 02b3b55d6aea2f26a0ddfcd8967597fb0d38d7c6c4027f0595f5a614b9f06400

class BlumBlumShub
{
    private $p, $q, $s, $m, $init, $x0;
    private $size = 1024;

    public function __construct($size = false, $p = false, $q = false, $s = false)
    {
        if($p !== false && $q !== false && $s !== false)
        {
            $this->p = $p;
            $this->q = $q;
            $this->m = bcmul($p, $q);
            $this->s = $s;
        } else {
            if($size !== false)
                $this->size = $size;
            $this->init();
        }
        
        $this->xn = bcmod(bcmul($this->s, $this->s), $this->m);
        for($i=0;$i<10;$i++)
            $this->xn = bcmod(bcmul($this->xn, $this->xn), $this->m);
    }
    
    private function init()
    {
        $this->p = $this->genPrime();
        $this->q = $this->genPrime();
        $this->m = bcmul($this->p, $this->q);
        
        $mCoPrime = gmp_init($this->m);

        # try find co-prime
        while(1)
        {
            $s = genPrime($this->size);
            $sCoPrime = gmp_init($s);
            $g = gmp_gcdext($mCoPrime, $sCoPrime);
            $g = gmp_strval($g['g']);
            if($g === '1')
                break;
        }

        $this->s = $s;
    }
    
    public function genPrime()
    {
        while(1)
        {
            $min = gmp_init(str_pad('1', $this->size, '0'));
            $max = gmp_init(str_pad('9', $this->size, '0'));
            $prime = gmp_strval(gmp_random_range($min, $max));

            $validate = bcmod($prime, '4');
            if($validate === '3')
                break;
        }

        return $prime;
    }
    
    public function getRandomPseudoBytes($length)
    {
        $bytes = '';
    
        for($i=0;$i<$length;$i++)
            $bytes .= $this->getByte();
        
        return $bytes;
    }
    
    public function getByte()
    {
        $byte = '';

        for($i=0;$i<8;$i++) {
            $this->xn = bcmod(bcmul($this->xn, $this->xn), $this->m);
            $byte .= substr(decbin($this->xn[strlen($this->xn)-1]), -1);
        }
        
        return chr(bindec($byte));
    }
}
?>

down

-6

yendrrek at gmail dot com ¶

1 year ago


mcrypt_create_iv

Warning
This function was DEPRECATED in PHP 7.1.0, and REMOVED in PHP 7.2.0.

https://www.php.net/manual/en/function.mcrypt-create-iv.php

down

-8

ccb2357 at gmail dot com ¶

2 years ago


<?php
    // PHP >= 7
    function str_rand(int $length = 20){
        $ascii_codes = range(48, 57) + range(97, 122);
        $codes_lenght = (count($ascii_codes)-1);
        shuffle($ascii_codes);
        $string = '';
        for($i = 1; $i <= $length; $i++){
            $previous_char = $char ?? '';
            $char = chr($ascii_codes[random_int(0, $codes_lenght)]);
            while($char == $previous_char){
                $char = chr($ascii_codes[random_int(0, $codes_lenght)]);
            }
            $string .= $char;
        }
        return $string;
    }
?>

down

-41

ccb_bc at hotmail dot com ¶

4 years ago


function str_rand($largura = 32){
        $chars = str_shuffle('0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz');
        // separar a string acima com uma virgula após cada letra ou número;
        $chars = preg_replace("/([a-z0-9])/i", "$1,", $chars);
        $chars = explode(',', $chars);

        $string_generate = array();
        for($i = 0; $i < $largura; $i++){
            // $chars[random_int(0, 61) = largura da array $chars
            array_push($string_generate, $chars[random_int(0, 61)]);
        }
        $string_ready = str_shuffle(implode($string_generate));
        
        for($i = 0; $i < random_int(256,512); $i++){
            $random_string = str_shuffle($string_ready);
        }
        // se a largura for um número par o numero de caracteres da string for maior ou igual a 4
        if($largura % 2 === 0 && strlen($random_string) >= 4){
            $random_string_start = str_shuffle(substr($random_string, 0, $largura / 2));
            $random_string_end = str_shuffle(substr($random_string, $largura / 2, $largura));
            $new_random_string = str_shuffle($random_string_start . $random_string_end);
            return str_shuffle($new_random_string);
        } 
        else {
            return str_shuffle($random_string);
        }
    }

down

-42

atesin () gmail ! com ¶

4 years ago


if unavailable use this with core functions... maybe not as secure and optimized (any help?), but practical

<?php

$bytes = '';
while (strlen($bytes) < $lenght)
  $bytes .= chr(mt_rand(0, 255));

?>

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