echo

crc32

[edit] Last updated: Sat, 07 Jan 2012

crypt

(PHP 4, PHP 5)

crypt — 단방향 문자열 암호화(해시)

설명

string crypt ( string $str [, string $salt ] )

crypt()는 표준 유닉스 DES 기반 암호화 알고리즘이나 시스템에서 사용할 수 있는 다양한 알고리즘을 사용하여 암호화한 문자열을 반환합니다.

몇몇 운영체제는 한가지 이상의 암호화 방식을 제공합니다. 사실, 종종 표준 DES 기반 암호화는 MD5 기반 암호화 알고리즘으로 대체되기도 합니다. 암호화 타입은 slat 인수에 의해 변경됩니다. 설치시에, PHP는 사용할 수 있는 암호화 함수를 판단하고, 다른 암호화 방식을 위한 salt를 받아들입니다. salt를 지정하지 않으면, PHP는 기본값으로 두 문자 salt를 자동 생성합니다. 단, 시스템의 기본 암호화 방식이 MD5라면, 무작위의 MD5 호환 salt를 생성합니다. PHP는 CRYPT_SALT_LENGTH 상수를 설정하여, 시스템에서 일반적인 두 문자 salt가 적용되는지, 혹은 12 문자 salt를 받아들일 수 있는지 알려줍니다.

표준 DES 기반 암호화 crypt()는 처음 두 문자가 salt 인 문자열을 출력합니다. 또한 str의 처음 8 문자만 사용하기에, 같은 8문자로 시작하는 긴 문자열은 (같은 salt를 사용하는 한) 같은 결과를 생성합니다.

crypt() 함수가 다양한 암호화 방식을 지원하는 시스템에서, 주어진 방식의 사용 가능 여부에 따라 다음 상수들이 0이나 1로 설정됩니다:

CRYPT_STD_DES - 2문자 salt를 가지는 표준 DES 기반 암호화
CRYPT_EXT_DES - 9문자 salt를 가지는 확장 DES 기반 암호화
CRYPT_MD5 - $1$로 시작하는 12문자 salt를 가지는 MD5 암호화
CRYPT_BLOWFISH - $2$나 $2a$로 시작하는 16문자 salt를 가지는 Blowfish 암호화

Note:
PHP 5.3.0부터, 시스템에서 지원하지 않는 알고리즘에 대해서 PHP의 구현을 가집니다.

인수

str

암호화할 문자열.

salt

암호화에 사용할 선택적인 salt 문자열. 주어지지 않으면, 이 함수를 호출할 때마다 PHP가 임의로 생성합니다.

salt를 제공하여 사용하면, salt가 한번 생성되어진 점에 주의해야 합니다. 이 함수를 반복적으로 호출하면, 표현과 보안에 모두 영향을 줍니다.

반환값

암호화된 문자열을 반환합니다.

변경점

버전	설명
5.3.0	시스템에서 지원하지 않는 MD5 암호화, 표준 DES, 확장 DES, Blowfish 알고리즘에 대해서 PHP의 구현을 가집니다.

예제

Example #1 crypt() 예제


<?php
$password = crypt('mypassword'); // salt 자동 생성

/* 패스워드를 비교할 때, 다른 해싱 알고리즘을 사용하는 문제를
   피하기 위해서, crypt()가 생성한 전체 결과를 salt로 주어야
   합니다. (위에서 밝혔듯이, 표준 DES 기반 암호 해싱은 2 문자
   salt를 사용하지만, MD5 기반 해싱은 12 문자를 사용합니다) */
if (crypt($user_input, $password) == $password) {
   echo "패스워드 확인!";
}
?>

Example #2 htpasswd와 crypt() 사용하기


<?php
// password 설정
$password = 'mypassword';

// salt 자동 생성으로 해시 획득
$hash = crype($password);

Example #3 다양한 암호화 형식으로 crypt() 사용하기


<?php
if (CRYPT_STD_DES == 1) {
    echo '표준 DES: ' . crypt('rasmuslerdorf', 'rl') . "\n";
}

if (CRYPT_EXT_DES == 1) {
    echo '확장 DES: ' . crypt('rasmuslerdorf', 'J9..rasm') . "\n";
}

if (CRYPT_MY5 == 1) {
    echo 'MD5:      ' . crypt('rasmuslerdorf', '$1$rasmusle$') . "\n";
}

if (CRYPT_STD_DES == 1) {
    echo 'Blowfish: ' . crypt('rasmuslerdorf', '$2a$07$rasmuslerd...........$') . "\n";
}
?>

위 예제의 출력 예시:

표준 DES: rl.3StKT.4T8M
확장 DES: _J9..rasmBYk8r9AiWNc
MD5     : $1$rasmusle$rISCgZzpwk3UhDidwXvin0
Blowfish:
$2a$07$rasmuslerd............nIdrcHdxcUxWomQX9j6kvERCFjTg7Ra

주의

Note: crypt()는 단방향 알고리즘을 사용하기 때문에, 복호화 함수는 없습니다.

참고

md5() - 문자열의 md5 해시를 계산
Mcrypt 확장
자세한 정보를 위해 crypt 함수에 관한 유닉스 man 페이지

echo

crc32

[edit] Last updated: Sat, 07 Jan 2012

add a note User Contributed Notes crypt

Matteo 18-May-2012 10:39


Password hashing should be done only with crypt and NEVER with SHA* and MD5 or hash(). The fundamental reason is that crypt is designed to be SLOW which is a VERY good thing for password hashing.





It also automatically generate a salt every time which makes pre-computed tables to "decrypt" passwords useless (the generated salt is stored in the returned string for convenience).

chris at ocportal dot com 29-Mar-2012 09:49


If you need to support older versions of PHP be aware that constants such as CRYPT_BLOWFISH may not actually be defined. So rather than following Example #3, you need a defined('CRYPT_...') call there before checking the constant's value.

Anonymous 19-Feb-2012 09:21


This function is not binary safe. Any binary string containing a NULL byte (chr(0)) will not produce a valid hash.

harry at simans dot net 27-Sep-2011 04:34


I made a nice little wrapper function for crypt():





<?php


function hasher($info, $encdata = false)


{


  $strength = "08";


  //if encrypted data is passed, check it against input ($info)


  if ($encdata) {


    if (substr($encdata, 0, 60) == crypt($info, "$2a$".$strength."$".substr($encdata, 60))) {


      return true;


    }


    else {


      return false;


    }


  }


  else {


  //make a salt and hash it with input, and add salt to end


  $salt = "";


  for ($i = 0; $i < 22; $i++) {


    $salt .= substr("./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789", mt_rand(0, 63), 1);


  }


  //return 82 char string (60 char hash & 22 char salt)


return crypt($info, "$2a$".$strength."$".$salt).$salt;


}


}


?>





This wrapper will accept a string as input and hash it, and output the hash result of the string and salt together, plus the salt added on the end. You can then store that output in a db, and pass it on to the function as the 2nd parameter when you go to verify it, along with the user input or whatever as the first.





Examples:





<?php


$hash = hasher($userinput);


if ($hash == hasher($userinput, $hash) {//authed}


?>





Neat huh?

kaminski at istori dot com 05-Feb-2011 03:43


Here is an expression to generate pseudorandom salt for the CRYPT_BLOWFISH hash type:



<?php $salt = substr(str_replace('+', '.', base64_encode(pack('N4', mt_rand(), mt_rand(), mt_rand(), mt_rand()))), 0, 22); ?>



It is intended for use on systems where mt_getrandmax() == 2147483647.



The salt created will be 128 bits in length, padded to 132 bits and then expressed in 22 base64 characters.  (CRYPT_BLOWFISH only uses 128 bits for the salt, even though there are 132 bits in 22 base64 characters.  If you examine the CRYPT_BLOWFISH input and output, you can see that it ignores the last four bits on input, and sets them to zero on output.)



Note that the high-order bits of the four 32-bit dwords returned by mt_rand() will always be zero (since mt_getrandmax == 2^31), so only 124 of the 128 bits will be pseudorandom.  I found that acceptable for my application.

php at nospam dot nowhere dot com 26-Aug-2009 07:21


The makesalt() function code below when used to create an MD5 salt, produces a salt with characters not typically in a salt used by operating system crypt functions.  Some of these characters may have unintended side effects depending on how they are used - including the following: @ ` ~ \ | {}.



I am using the following to create MD5-Crypt hashes, (yes, I am assuming CRYPT_MD5 support is present).



<?php

function md5crypt($password){

    // create a salt that ensures crypt creates an md5 hash

    $base64_alphabet='ABCDEFGHIJKLMNOPQRSTUVWXYZ'

                    .'abcdefghijklmnopqrstuvwxyz0123456789+/';

    $salt='$1$';

    for($i=0; $i<9; $i++){

        $salt.=$base64_alphabet[rand(0,63)];

    }

    // return the crypt md5 password

    return crypt($password,$salt.'$');

}

?>

Jou 06-Apr-2007 01:52


I found out that you can use php:s crypt function to change  the user/root password in Linux distributions (at least in Slackware).



You just have to change the encrypted password for the user in the /etc/shadow file with the output from crypt("newpassword");

mikey_nich (at) hotmáil . com 04-Mar-2007 07:47


Are you using Apache2 on f.i. WinXP and want to create .htpasswd files via php? Then you need to use the APR1-MD5 encryption method. Here is a function for that:



<?php



function crypt_apr1_md5($plainpasswd) {

    $salt = substr(str_shuffle("abcdefghijklmnopqrstuvwxyz0123456789"), 0, 8);

    $len = strlen($plainpasswd);

    $text = $plainpasswd.'$apr1$'.$salt;

    $bin = pack("H32", md5($plainpasswd.$salt.$plainpasswd));

    for($i = $len; $i > 0; $i -= 16) { $text .= substr($bin, 0, min(16, $i)); }

    for($i = $len; $i > 0; $i >>= 1) { $text .= ($i & 1) ? chr(0) : $plainpasswd{0}; }

    $bin = pack("H32", md5($text));

    for($i = 0; $i < 1000; $i++) {

        $new = ($i & 1) ? $plainpasswd : $bin;

        if ($i % 3) $new .= $salt;

        if ($i % 7) $new .= $plainpasswd;

        $new .= ($i & 1) ? $bin : $plainpasswd;

        $bin = pack("H32", md5($new));

    }

    for ($i = 0; $i < 5; $i++) {

        $k = $i + 6;

        $j = $i + 12;

        if ($j == 16) $j = 5;

        $tmp = $bin[$i].$bin[$k].$bin[$j].$tmp;

    }

    $tmp = chr(0).chr(0).$bin[11].$tmp;

    $tmp = strtr(strrev(substr(base64_encode($tmp), 2)),

    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/",

    "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz");

    return "$"."apr1"."$".$salt."$".$tmp;

}



?>

picolobo at pilab dot dyndns dot org 21-Sep-2006 01:49


I had problems with ENCRYPT MySQL function when i tried to compare with the encrypted password (with ENCRYPT).



Another solution i read from "UNIX Advanced programming" where i found about the UNIX system call "crypt()":



Password="tB" //The two first letters of encrypted password



SELECT password from users where Password=ENCRYPT('".$_POST['password']."',Password)



mysql> select password from users where password=encrypt('pasword','tB');

+---------------+

| password      |

+---------------+

| tBY8OVuabSiTU |

+---------------+

1 row in set (0.01 sec)



Bye.



> topace at lightbox dot org

> 22-Sep-2005 06:34

>

> To authenticate against a stored crypt in MySQL, simply use:

>

> SELECT ................

>           AND Password=ENCRYPT('".$_POST['password']."',Password)

solar at openwall dot com 23-Dec-2005 11:20


With different password hashing methods supported on different systems and with the need to generate salts with your own PHP code in order to use the more advanced / more secure methods, it takes special knowledge to use crypt() optimally, producing strong password hashes.  Other message digest / hashing functions supported by PHP, such as md5() and sha1(), are really no good for password hashing if used naively, resulting in hashes which may be brute-forced at rates much higher than those possible for hashes produced by crypt().



I have implemented a PHP password hashing framework (in PHP, tested with all of PHP 3, 4, and 5) which hides the complexity from your PHP applications (no need for you to worry about salts, etc.), yet does things in almost the best way possible given the constraints of the available functions.  The homepage for the framework is:



http://www.openwall.com/phpass/



I have placed this code in the public domain, so there are no copyrights or licensing restrictions to worry about.



P.S. I have 10 years of experience in password (in)security and I've developed several other password security tools and libraries.  So most people can feel confident they're getting this done better by using my framework than they could have done it on their own.

hotdog (at) gmx (dot) net 16-Nov-2005 07:34


WRONG:



$mypassword = "toto";

$smd5_pass = "{SMD5}......." // in openldap



if (preg_match ("/{SMD5}/i", $smd5_pass))

 {

  $encrypted = substr($md5_pass, 6);

  $hash = base64_decode($encrypted);

  $salt = substr($hash,16);

  $mhashed =  mhash(MHASH_MD5, $mypassword . $salt) ;

  $without_salt = explode($salt,$hash_hex);

   if ($without_salt[0] == $mhashed) {

    echo "Password verified <br>";

    } else {

    echo "Password Not verified<br>";

    }

 }



$without_salt = explode($salt,$hash_hex); should be $without_salt = explode($salt,$hash); 



RIGHT:



$mypassword = "toto";

$smd5_pass = "{SMD5}......." // in openldap



if (preg_match ("/{SMD5}/i", $smd5_pass))

 {

  $encrypted = substr($md5_pass, 6);

  $hash = base64_decode($encrypted);

  $salt = substr($hash,16);

  $mhashed =  mhash(MHASH_MD5, $mypassword . $salt) ;

  $without_salt = explode($salt,$hash);

   if ($without_salt[0] == $mhashed) {

    echo "Password verified <br>";

    } else {

    echo "Password Not verified<br>";

    }

 }

Vlad Alexa Mancini mancin at nextcode dot org 15-May-2005 01:57


cleaner version of shadow() and with more ascii chars



<?php



function shadow ($input){

         for ($n = 0; $n < 9; $n++){

              $s .= chr(rand(64,126));

         }

         $seed =  "$1$".$s."$";

         $return = crypt($input,$seed);

    return $return;

}



>

thorhajo at gmail dot com 02-Sep-2004 03:34


Here's a little function I wrote to generate MD5 password hashes in the format they're found in /etc/shadow:



function shadow($password)

{

  $hash = '';

  for($i=0;$i<8;$i++)

  {

    $j = mt_rand(0,53);

    if($j<26)$hash .= chr(rand(65,90));

    else if($j<52)$hash .= chr(rand(97,122));

    else if($j<53)$hash .= '.';

    else $hash .= '/';

  }

  return crypt($password,'$1$'.$hash.'$');

}



I've written this so that each character in the a-zA-Z./ set has a 1/54 of a chance of being selected (26 + 26 + 2 = 54), thus being statistically even.

aidan at php dot net 05-Jul-2004 07:52


Text_Password allows one to create pronounceable and unpronounceable passwords.



http://pear.php.net/package/text_password

add a note