임의의 5 자 문자열 생성

임의의 5 자 문자열 생성

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중복 될 가능성이 가장 적은 정확한 5 개의 임의 문자열을 만들고 싶습니다. 이를 수행하는 가장 좋은 방법은 무엇입니까? 감사.

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$rand = substr(md5(microtime()),rand(0,26),5);

내 추측은 아마도 특수 문자를 찾는 것이 아니라면 다음과 같다.

$seed = str_split('abcdefghijklmnopqrstuvwxyz'
                 .'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
                 .'0123456789!@#$%^&*()'); // and any other characters
shuffle($seed); // probably optional since array_is randomized; this may be redundant
$rand = '';
foreach (array_rand($seed, 5) as $k) $rand .= $seed[$k];

예

그리고 시계를 기반으로 한 경우 (증분이므로 충돌이 적음) :

function incrementalHash($len = 5){
  $charset = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
  $base = strlen($charset);
  $result = '';

  $now = explode(' ', microtime())[1];
  while ($now >= $base){
    $i = $now % $base;
    $result = $charset[$i] . $result;
    $now /= $base;
  }
  return substr($result, -5);
}

참고 : 증분은 추측하기 쉽다는 것을 의미합니다. 이것을 솔트 또는 인증 토큰으로 사용하는 경우 사용하지 마십시오. "WCWyb"의 솔트 (현재)는 5 초 후 "WCWyg"임을 의미합니다.)

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for루프가 부족한 경우 사용하고 싶은 것은 다음과 같습니다.

$s = substr(str_shuffle(str_repeat("0123456789abcdefghijklmnopqrstuvwxyz", 5)), 0, 5);

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빠른 방법은 uniqid 함수 의 가장 변덕스러운 문자를 사용하는 것입니다.

예를 들면 :

$rand = substr(uniqid('', true), -5);

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다음과 같이 간단하게 시도 할 수 있습니다.

$length = 5;

$randomletter = substr(str_shuffle("abcdefghijklmnopqrstuvwxyz"), 0, $length);

자세한 내용 : http://forum.arnlweb.com/viewtopic.php?f=7&t=25

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다음은 중복 가능성을 최소화해야합니다 ( mt_rand()예 /dev/*random: GUID 에서 또는 GUID 에서 더 나은 난수 소스 로 대체 할 수 있음 ).

<?php
    $characters = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
    $result = '';
    for ($i = 0; $i < 5; $i++)
        $result .= $characters[mt_rand(0, 61)];
?>

편집 :
당신이 보안에 대해 우려하는 경우, 정말 할 수 없습니다 사용 rand()하거나 mt_rand(), 당신의 임의의 데이터 장치가 실제로 발생 장치인지 확인 임의 의 데이터가 아닌 일반 파일 또는 같은 예측 뭔가를 /dev/zero. mt_rand()유해한 것으로 간주 :
https://spideroak.com/blog/20121205114003-exploit-information-leaks-in-random-numbers-from-python-ruby-and-php

편집 : PHP에서 OpenSSL을 지원하는 경우 다음을 사용할 수 있습니다 openssl_random_pseudo_bytes().

<?php
    $length = 5;
    $randomBytes = openssl_random_pseudo_bytes($length);
    $characters = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
    $charactersLength = strlen($characters);
    $result = '';
    for ($i = 0; $i < $length; $i++)
        $result .= $characters[ord($randomBytes[$i]) % $charactersLength];
?>

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나는 항상 이것에 대해 동일한 기능을 사용하며 일반적으로 암호를 생성합니다. 사용하기 쉽고 유용합니다.

function randPass($length, $strength=8) {
    $vowels = 'aeuy';
    $consonants = 'bdghjmnpqrstvz';
    if ($strength >= 1) {
        $consonants .= 'BDGHJLMNPQRSTVWXZ';
    }
    if ($strength >= 2) {
        $vowels .= "AEUY";
    }
    if ($strength >= 4) {
        $consonants .= '23456789';
    }
    if ($strength >= 8) {
        $consonants .= '@#$%';
    }

    $password = '';
    $alt = time() % 2;
    for ($i = 0; $i < $length; $i++) {
        if ($alt == 1) {
            $password .= $consonants[(rand() % strlen($consonants))];
            $alt = 0;
        } else {
            $password .= $vowels[(rand() % strlen($vowels))];
            $alt = 1;
        }
    }
    return $password;
}

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It seems like str_shuffle would be a good use for this. Seed the shuffle with whichever characters you want.

$my_rand_strng = substr(str_shuffle("ABCDEFGHIJKLMNOPQRSTUVWXYZ"), -5);

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$str = '';
$str_len = 8;
for($i = 0, $i < $str_len; $i++){
    //97 is ascii code for 'a' and 122 is ascii code for z
    $str .= chr(rand(97, 122));
}
return $str

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If it's fine that you'll get only letters A-F, then here's my solution:

str_pad(dechex(mt_rand(0, 0xFFFFF)), 5, '0', STR_PAD_LEFT);

I believe that using hash functions is an overkill for such a simple task as generating a sequence of random hexadecimal digits. dechex + mt_rand will do the same job, but without unnecessary cryptographic work. str_pad guarantees 5-character length of the output string (if the random number is less than 0x10000).

Duplicate probability depends on mt_rand's reliability. Mersenne Twister is known for high-quality randomness, so it should fit the task well.

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I also did not know how to do this until I thought of using PHP array's. And I am pretty sure this is the simplest way of generating a random string or number with array's. The code:

function randstr ($len=10, $abc="aAbBcCdDeEfFgGhHiIjJkKlLmMnNoOpPqQrRsStTuUvVwWxXyYzZ0123456789") {
    $letters = str_split($abc);
    $str = "";
    for ($i=0; $i<=$len; $i++) {
        $str .= $letters[rand(0, count($letters)-1)];
    };
    return $str;
};

You can use this function like this

randstr(20)     // returns a random 20 letter string
                // Or like this
randstr(5, abc) // returns a random 5 letter string using the letters "abc"

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Similar to Brad Christie's answer, but using sha1 alrorithm for characters 0-9a-zA-Z and prefixed with a random value :

$str = substr(sha1(mt_rand() . microtime()), mt_rand(0,35), 5);

But if you have set a defined (allowed) characters :

$validChars = array('0','1','2' /*...*/,'?','-','_','a','b','c' /*...*/);
$validCharsCount = count($validChars);

$str = '';
for ($i=0; $i<5; $i++) {
    $str .= $validChars[rand(0,$validCharsCount - 1)];
}

** UPDATE **

As Archimedix pointed out, this will not guarantee to return a "least possibility of getting duplicated" as the number of combination is low for the given character range. You will either need to increase the number of characters, or allow extra (special) characters in the string. The first solution would be preferable, I think, in your case.

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works fine in PHP (php 5.4.4)

$seed = str_split('abcdefghijklmnopqrstuvwxyz');
$rand = array_rand($seed, 5);
$convert = array_map(function($n){
    global $seed;
    return $seed[$n];
},$rand);

$var = implode('',$convert);
echo $var;

Live Demo

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Source: PHP Function that Generates Random Characters

This simple PHP function worked for me:

function cvf_ps_generate_random_code($length=10) {

   $string = '';
   // You can define your own characters here.
   $characters = "23456789ABCDEFHJKLMNPRTVWXYZabcdefghijklmnopqrstuvwxyz";

   for ($p = 0; $p < $length; $p++) {
       $string .= $characters[mt_rand(0, strlen($characters)-1)];
   }

   return $string;

}

Usage:

echo cvf_ps_generate_random_code(5);

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Here are my random 5 cents ...

$random=function($a, $b) {
    return(
        substr(str_shuffle(('\\`)/|@'.
        password_hash(mt_rand(0,999999),
        PASSWORD_DEFAULT).'!*^&~(')),
        $a, $b)
    );
};

echo($random(0,5));

PHP's new password_hash() (* >= PHP 5.5) function is doing the job for generation of decently long set of uppercase and lowercase characters and numbers.

Two concat. strings before and after password_hash within $random function are suitable for change.

Paramteres for $random() *($a,$b) are actually substr() parameters. :)

NOTE: this doesn't need to be a function, it can be normal variable as well .. as one nasty singleliner, like this:

$random=(substr(str_shuffle(('\\`)/|@'.password_hash(mt_rand(0,999999), PASSWORD_DEFAULT).'!*^&~(')), 0, 5));

echo($random);

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I`ve aways use this:

<?php function fRand($len) {
    $str = '';
    $a = "abcdefghijklmnopqrstuvwxyz0123456789";
    $b = str_split($a);
    for ($i=1; $i <= $len ; $i++) { 
        $str .= $b[rand(0,strlen($a)-1)];
    }
    return $str;
} ?>

When you call it, sets the lenght of string.

<?php echo fRand([LENGHT]); ?>

You can also change the possible characters in the string $a.

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function CaracteresAleatorios( $Tamanno, $Opciones) {
    $Opciones = empty($Opciones) ? array(0, 1, 2) : $Opciones;
    $Tamanno = empty($Tamanno) ? 16 : $Tamanno;
    $Caracteres=array("0123456789","abcdefghijklmnopqrstuvwxyz","ABCDEFGHIJKLMNOPQRSTUVWXYZ");
    $Caracteres= implode("",array_intersect_key($Caracteres, array_flip($Opciones)));
    $CantidadCaracteres=strlen($Caracteres)-1;
    $CaracteresAleatorios='';
    for ($k = 0; $k < $Tamanno; $k++) {
        $CaracteresAleatorios.=$Caracteres[rand(0, $CantidadCaracteres)];
    }
    return $CaracteresAleatorios;
}

참고URL : https://stackoverflow.com/questions/5438760/generate-random-5-characters-string