crypt

jette at nerdgirl dot dk (2013-04-25 07:48:27)

The crypt() function cant handle plus signs correctly. So if for example you are using crypt in a login function, use urlencode on the password first to make sure that the login procedure can handle any character:

<?php
$user_input =  '12+#?345';
$pass = urlencode($user_input));
$pass_crypt = crypt($pass);

if ($pass_crypt == crypt($pass, $pass_crypt)) {
  echo "Success! Valid password";
} else {
  echo "Invalid password";
} 
?>

mblaney at gmail dot com (2013-04-22 01:46:14)

For those wondering, like I did, what the maximum length of the returned hash can be for the purpose of storing it in a database, the answer is:
123 characters.

Denver Timothy (2013-03-13 17:28:40)

Here is my blowfish-crypt function:

<?php
    function bcrypt($input, $salt=null, $rounds=12) {
        if($rounds < 4 || $rounds > 31) $rounds = 12;
        if(is_null($salt)) $salt = sprintf('$2a$%02d$', $rounds).substr(str_replace('+', '.', base64_encode(pack('N4', mt_rand(), mt_rand(), mt_rand(), mt_rand()))), 0, 22);
        return crypt($input, $salt);
    }
    $hash = bcrypt('password');
    if($hash = bcrypt('password', $hash)) {
        // password ok
    }
?>

steve at tobtu dot com (2013-01-13 00:26:27)

To generate salt use mcrypt_create_iv() not mt_rand() because no matter how many times you call mt_rand() it will only have at most 32 bits of entropy. Which you will start seeing salt collisions after about 2^16 users. mt_rand() is seeded poorly so it should happen sooner.

For bcrypt this will actually generate a 128 bit salt:
<?php $salt = strtr(base64_encode(mcrypt_create_iv(16, MCRYPT_DEV_URANDOM)), '+', '.'); ?>

*** Bike shed ***
The last character in the 22 character salt is 2 bits.
base64_encode() will have these four character "AQgw"
bcrypt will have these four character ".Oeu"

You don't need to do a full translate because they "round" to different characters:
echo crypt('', '$2y$05$.....................A') . "\n";
echo crypt('', '$2y$05$.....................Q') . "\n";
echo crypt('', '$2y$05$.....................g') . "\n";
echo crypt('', '$2y$05$.....................w') . "\n";

$2y$05$......................J2ihDv8vVf7QZ9BsaRrKyqs2tkn55Yq
$2y$05$.....................O/jw2XygQa2.LrIT7CFCBQowLowDP6Y.
$2y$05$.....................eDOx4wMcy7WU.kE21W6nJfdMimsBE3V6
$2y$05$.....................uMMcgjnOELIa6oydRivPkiMrBG8.aFp.

jon dot hulka at gmail dot com (2012-10-31 05:34:42)

Along the lines of the md5crypt, but for blowfish
<?php
function blowfishCrypt($password,$cost)
{
    $chars='./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
    $salt=sprintf('$2a$%02d$',$cost);
    for($i=0;$i<22;$i++) $salt.=$chars[rand(0,63)];
    return crypt($password,$salt);
}

//Example:
$hash=blowfishCrypt('password',10);
if(crypt('password',$hash)==$hash){ /*ok*/ }
?>

Matteo (2012-05-18 22:39:19)

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).

harry at simans dot net (2011-09-27 04:34:16)

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 (2011-02-05 15:43:47)

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.

mikey_nich (at) hotmáil . com (2007-03-04 07:47:35)

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;
}

?>

solar at openwall dot com (2005-12-23 23:20:13)

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 (2005-11-16 07:34:00)

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>";
}
}

thorhajo at gmail dot com (2004-09-02 15:34:10)

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 (2004-07-05 07:52:49)

Text_Password allows one to create pronounceable and unpronounceable passwords.
http://pear.php.net/package/text_password