字符串函数
在线手册：中文 英文
PHP手册

crypt

(PHP 4, PHP 5)

crypt — 单向字符串散列

说明

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

crypt() 返回一个基于标准 UNIX DES 算法或系统上其他可用的替代算法的散列字符串。

有些系统支持不止一种散列类型。实际上，有时候，基于 MD5 的算法被用来替代基于标准 DES 的算法。这种散列类型由盐值参数触发。在 5.3 之前，PHP 在安装时根据系统的 crypt() 决定可用的算法。如果没有提供盐值，PHP 将自动生成一个 2 个字符（DES）或者 12 个字符（MD5）的盐值 ，这取决于 MD5 crypt() 的可用性。PHP 设置了一个名为 CRYPT_SALT_LENGTH 的常量，用来表示可用散列允许的最长可用盐值。

基于标准 DES 算法的 crypt() 在输出内容的开始位置返回两个字符的盐值。它也只使用 str 的开始 8 个字符，所以更长的以相同 8 个字符开始的字符串也将生成相同的结果（当使用了相同的盐值时）。

在 crypt() 函数支持多重散列的系统上，下面的常量根据相应的类型是否可用被设置为 0 或 1：

Note:

从 PHP 5.3.0 起，PHP 包含了它自己的实现，并将在系统缺乏相应算法支持的时候使用它自己的实现。

参数

str

待散列的字符串。

salt

可选的盐值字符串。如果没有提供，算法行为将由不同的算法实现决定，并可能导致不可预料的结束。

返回值

返回散列后的字符串或一个少于 13 字符的字符串，从而保证在失败时与盐值区分开来。

更新日志

版本 说明
5.3.2 基于 Ulrich Drepper 的» 实现，新增基于 SHA-256 算法和 SHA-512 算法的 crypt。
5.3.2 修正了 Blowfish 算法由于非法循环导致的问题，返回“失败”字符串（“*0” 或 “*1”）而不是转而使用 DES 算法。
5.3.0 PHP 现在包含了它自己的 MD5 Crypt 实现，包括标准 DES 算法，扩展的 DES 算法以及 Blowfish 算法。如果系统缺乏相应的实现，那么 PHP 将使用它自己的实现。

范例

Example #1 crypt() 范例

<?php
$password = crypt('mypassword'); // 自动生成盐值

/* 你应当使用 crypt() 得到的完整结果作为盐值进行密码校验，以此来避免使用不同散列算法导致的问题。（如上所述，基于标准 DES 算法的密码散列使用 2 字符盐值，但是基于 MD5 算法的散列使用 12 个字符盐值。）*/
if (crypt($user_input, $password) == $password) {
   echo "Password verified!";
}
?>

Example #2 利用 htpasswd 进行 crypt() 加密

<?php
// 设置密码
$password = 'mypassword';

// 获取散列值，使用自动盐值
$hash = crypt($password);
?>

Example #3 以不同散列类型使用 crypt()

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

if (CRYPT_EXT_DES == 1) {
    echo 'Extended DES: ' . crypt('rasmuslerdorf', '_J9..rasm') . "\n";
}

if (CRYPT_MD5 == 1) {
    echo 'MD5:          ' . crypt('rasmuslerdorf', '$1$rasmusle$') . "\n";
}

if (CRYPT_BLOWFISH == 1) {
    echo 'Blowfish:     ' . crypt('rasmuslerdorf', '$2a$07$usesomesillystringforsalt$') . "\n";
}

if (CRYPT_SHA256 == 1) {
    echo 'SHA-256:      ' . crypt('rasmuslerdorf', '$5$rounds=5000$usesomesillystringforsalt$') . "\n";
}

if (CRYPT_SHA512 == 1) {
    echo 'SHA-512:      ' . crypt('rasmuslerdorf', '$6$rounds=5000$usesomesillystringforsalt$') . "\n";
}
?>

以上例程的输出类似于：

Standard DES: rl.3StKT.4T8M
Extended DES: _J9..rasmBYk8r9AiWNc
MD5:          $1$rasmusle$rISCgZzpwk3UhDidwXvin0
Blowfish:     $2a$07$usesomesillystringfore2uDLvp1Ii2e./U9C8sBjqp8I90dH6hi
SHA-256:      $5$rounds=5000$usesomesillystri$KqJWpanXZHKq2BOB43TSaYhEWsQ1Lr5QNyPCDH/Tp.6
SHA-512:      $6$rounds=5000$usesomesillystri$D4IrlXatmP7rx3P3InaxBeoomnAihCKRVQP22JZ6EY47Wc6BkroIuUUBOov1i.S5KPgErtP/EN5mcO.ChWQW21

注释

Note: 由于 crypt() 使用的是单向算法，因此不存在 decrypt 函数。

参见

字符串函数
在线手册：中文 英文
PHP手册
PHP手册 - N: 单向字符串散列

用户评论:

aeomer (07-Apr-2012 03:20)

To: Anonymous 19-Feb-2012 07:05

The reason you are finding 'collisions' is your salt is invalid. As such you are comparing two error messages as being equal.
Please RTFM.

See http://www.openwall.com/phpass/ for a proper implementation of a salt generator for crypt.

Anonymous (07-Apr-2012 03:19)

To: Anonymous 19-Feb-2012 07:05

The reason you are finding 'collisions' is your salt is invalid. As such you are comparing two error messages as being equal.
Please RTFM.

See http://www.openwall.com/phpass/ for a proper implementation of a salt generator for crypt.

chris at ocportal dot com (29-Mar-2012 05:49)

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.

nsbidon at yahoo dot ca (22-Mar-2012 12:03)

This function works good for me

example :
$pass = "Hello123";
$number = rand(163245,978534);
$salt = crypto($pass,$number);

function crypto($p)
{

   $number = rand(163245,978534);
   $pass = crypt($p,$number);
   return md5($pass);

}
return 343a4ff560ca00da5dd9e40906904daa

Anonymous (20-Feb-2012 05:21)

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

Anonymous (19-Feb-2012 03:05)

I keep finding collisions, here is one (salt can be anything):
$one = base64_decode('AAOafeUhQlGwYrHtKe/0z/mCVciFIeIOhTicC1Rp8DJf4nmMsefGnMxncirXmBA=');
$two = base64_decode('AMOCK9gdS6zuaaOpbOQAL0vEn40=');
echo crypt($one, '$2a$07$usesomesillystringforsalt$') == crypt($two, '$2a$07$usesomesillystringforsalt$');//prints 1

Sergio D L (09-Feb-2012 12:35)

ircmaxell at php dot net :

"So there's no need to store the salt separately, since crypt() stores it inline for you..."

I wouldn't recommend that. When you're using Blowfish algorithm with a 22 char long salt (less may return *0), the last character will most likely be stripped out the string.

Like in this example:

<?php
$salt = '$2a$10$po8w4yriabndjhfq4toyta';
$pass = "will encrypt this";

echo "Salt:&nbsp;&nbsp;&nbsp; $salt <br />
        Returns:&nbsp;&nbsp;&nbsp;" . crypt($pass, $salt);

/*
----------------------
Will return:
Salt:    $2a$10$po8w4yriabndjhfq4toyta
Returns:   $2a$10$po8w4yriabndjhfq4toytO.Llhr8xTWXshX6imHrB9i.UNG6HDfBe
----------------------
*/
?>

You can see the last "a" is stripped out (returning only $2a$10 + 21charSalt + 32charHash).
Change the "a" to "m", and the hash will be succesfully changed to eYkPo.CiKcZJ..fIHeXVDutBs7JYAVNG
Odd enough, change it to "b", and you'll get the same Hash from the first example. And will happen with other characters.
This behavior has been documented in sites like stackoverflow when you ask "Why blowfish returns the same hash".

PHP version: 5.3.6-13ubuntu3.3

So better keep the original salt you built.
If you're constrained to the now obligatory 22 chars, most likely it will be truncated by crypt and you won't get the same hash if you try to reconstruct the hash with those 21 chars.
Might be worse if your crypt doesn't accept less than 22 chars, you won't get any return value.

Sorky (04-Feb-2012 09:03)

$salt = substr(str_shuffle("./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"), -22);

ircmaxell at php dot net (01-Feb-2012 10:38)

Harry at simans:

That's absolutely not necessary.  Crypt will automatically peel off the salt for you (and include it in the output).  You can add a function to generate the salt for you, but the crypt function works the same way your wrapper does:

<?php
function makeSalt() {
    static $seed = "./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
    $algo = '$2a';
    $strength = '$08';
    $salt = '$';
    for ($i = 0; $i < 22; $i++) {
        $salt .= substr($seed, mt_rand(0, 63), 1);
    }
    return $algo . $strength . $salt;
}

function makeHash($password) {
    return crypt($password, makeSalt());
}

function verifyHash($password, $hash) {
    return $hash == crypt($password, $hash);
}
?>

Which then means that this relation will always hold:

<?php

true === verifyHash($password, makeHash($password));

?>

So there's no need to store the salt separately, since crypt() stores it inline for you...

harry at simans dot net (27-Sep-2011 12:34)

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?

eleljrk at gmail dot com (21-Sep-2011 07:23)

I've seen many CRYPT_BLOWFISH salt generators, but none REALLY go into the depth of it. This give you a RANDOM string of 22 characters, the string can contain ANY OF THE ALLOWED characters for the salt. I wont claim this the best solution, but this is fairly much everything you can do with a random salt generator.

<?php

public function getSalt() {

    $c = explode(" ", ". / a A b B c C d D e E f F g G h H i I j J k K l L m M n N o O p P q Q r R s S t T u U v V w W x X y Y z Z 0 1 2 3 4 5 6 7 8 9");
    $ks = array_rand($c, 22);

    $s = "";
    foreach($ks as $k) { $s .= $c[$k]; }

    return $s;

}

?>

Take note that every allowed character is inside the $c variable, $s is the salt, $ks is for keys to use in salt and $k is key. There is probably a better and shorter script out there, but this is solid enough for me.

Have fun with the code.

kaminski at istori dot com (05-Feb-2011 11:43)

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.

Robin Leffmann (25-Dec-2010 02:23)

The salts for crypt() must follow the usual base64 ASCII pattern (./0-9A-Za-z only), but the payload string can contain any binary data.

Thomas Praxl (10-Jan-2010 05:28)

Note that crypt can cause hangs on Windows OS when used with a salt. This applies only to certain circumstances.

php at nospam dot nowhere dot com (27-Aug-2009 03:21)

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.'$');
}
?>

addiakogiannis at isds dot gr (13-Jul-2007 11:46)

Two siple functions for encrypting and decrypting with RIJNDAEL 256

function RIJNDAEL_encrypt($text){

    $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
    $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
    $key = "This is a very secret key";
    return base64_encode(mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key, $text, MCRYPT_MODE_ECB, $iv));
   
}

function RIJNDAEL_decrypt($text){

    $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
    $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
    $key = "This is a very secret key";
  //I used trim to remove trailing spaces
return trim(mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $key, base64_decode($text), MCRYPT_MODE_ECB, $iv));
   
}

//example
echo RIJNDAEL_decrypt(RIJNDAEL_encrypt('Her name was lola!'));

leth at nowhere dot not (06-Apr-2007 03:51)

for me(on OpenBSD4.0+Apache 1.3(standard)+php4.3.10) blowfish seems to work if you do something like this:

    if (CRYPT_BLOWFISH == 1)
    {
        $salt="this should really be a long line of salt";
        $blowfish_salt = "\$2a\$07\$".substr($salt, 0, CRYPT_SALT_LENGTH);
        echo crypt($pass, $blowfish_salt);
    }

of course with $salt set as a good long salt.

Jou (06-Apr-2007 09:52)

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 03:47)

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;
}

?>

tserong at sgi dot com (14-Dec-2006 08:18)

Blowfish doesn't use a sixteen character salt, it uses sixteen *bytes* of salt.  So (courtesy of the docs for the Crypt::Eksblowfish::Bcrypt Perl module), it's:

    "$2", optional "a", "$", two digits, "$", and 22 base 64 digits

If the salt is not long enough, crypt will return "*0" and you will have no idea what is wrong.  Interestingly, the example in the documentation with a trailing '$' in the salt does not work.  Replace the '$' with a '.', and the output appears as advertised.

picolobo at pilab dot dyndns dot org (21-Sep-2006 09:49)

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 (24-Dec-2005 07:20)

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 03:34)

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 09:57)

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 11:34)

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 03:52)

Text_Password allows one to create pronounceable and unpronounceable passwords.

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