crc32
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).
crypt
(PHP 4, PHP 5)
crypt — One-way string hashing
Descrierea
string crypt
( string
$str
[, string $salt
] )crypt() will return a hashed string using the standard Unix DES-based algorithm or alternative algorithms that may be available on the system.
Some operating systems support more than one type of hash. In
fact, sometimes the standard DES-based algorithm is replaced by an
MD5-based algorithm. The hash type is triggered by the salt argument.
Prior to 5.3, PHP would determine the available algorithms at install-time
based on the system's crypt(). If no salt is provided, PHP will
auto-generate either a standard two character (DES) salt, or a twelve
character (MD5), depending on the availability of MD5 crypt(). PHP sets a
constant named CRYPT_SALT_LENGTH which indicates the
longest valid salt allowed by the available hashes.
The standard DES-based crypt() returns the
salt as the first two characters of the output. It also only uses the
first eight characters of str, so longer strings
that start with the same eight characters will generate the same result
(when the same salt is used).
On systems where the crypt() function supports multiple hash types, the following constants are set to 0 or 1 depending on whether the given type is available:
-
CRYPT_STD_DES- Standard DES-based hash with a two character salt from the alphabet "./0-9A-Za-z". Using invalid characters in the salt will cause crypt() to fail. -
CRYPT_EXT_DES- Extended DES-based hash. The "salt" is a 9-character string consisting of an underscore followed by 4 bytes of iteration count and 4 bytes of salt. These are encoded as printable characters, 6 bits per character, least significant character first. The values 0 to 63 are encoded as "./0-9A-Za-z". Using invalid characters in the salt will cause crypt() to fail. -
CRYPT_MD5- MD5 hashing with a twelve character salt starting with $1$ -
CRYPT_BLOWFISH- Blowfish hashing with a salt as follows: "$2a$", a two digit cost parameter, "$", and 22 digits from the alphabet "./0-9A-Za-z". Using characters outside of this range in the salt will cause crypt() to return a zero-length string. The two digit cost parameter is the base-2 logarithm of the iteration count for the underlying Blowfish-based hashing algorithmeter and must be in range 04-31, values outside this range will cause crypt() to fail. -
CRYPT_SHA256- SHA-256 hash with a sixteen character salt prefixed with $5$. If the salt string starts with 'rounds=<N>$', the numeric value of N is used to indicate how many times the hashing loop should be executed, much like the cost parameter on Blowfish. The default number of rounds is 5000, there is a minimum of 1000 and a maximum of 999,999,999. Any selection of N outside this range will be truncated to the nearest limit. -
CRYPT_SHA512- SHA-512 hash with a sixteen character salt prefixed with $6$. If the salt string starts with 'rounds=<N>$', the numeric value of N is used to indicate how many times the hashing loop should be executed, much like the cost parameter on Blowfish. The default number of rounds is 5000, there is a minimum of 1000 and a maximum of 999,999,999. Any selection of N outside this range will be truncated to the nearest limit.
Notă:
As of PHP 5.3.0, PHP contains its own implementation and will use that if the system lacks of support for one or more of the algorithms.
Parametri
-
str -
The string to be hashed.
-
salt -
An optional salt string to base the hashing on. If not provided, the behaviour is defined by the algorithm implementation and can lead to unexpected results.
Valorile întoarse
Returns the hashed string or a string that is shorter than 13 characters and is guaranteed to differ from the salt on failure.
Istoria schimbărilor
| Versiunea | Descriere |
|---|---|
| 5.3.2 | Added SHA-256 and SHA-512 crypt based on Ulrich Drepper's » implementation. |
| 5.3.2 | Fixed Blowfish behaviour on invalid rounds to return "failure" string ("*0" or "*1"), instead of falling back to DES. |
| 5.3.0 | PHP now contains its own implementation for the MD5 crypt, Standard DES, Extended DES and the Blowfish algorithms and will use that if the system lacks of support for one or more of the algorithms. |
Exemple
Example #1 crypt() examples
<?php
$password = crypt('mypassword'); // let the salt be automatically generated
/* You should pass the entire results of crypt() as the salt for comparing a
password, to avoid problems when different hashing algorithms are used. (As
it says above, standard DES-based password hashing uses a 2-character salt,
but MD5-based hashing uses 12.) */
if (crypt($user_input, $password) == $password) {
echo "Password verified!";
}
?>
Example #2 Using crypt() with htpasswd
<?php
// Set the password
$password = 'mypassword';
// Get the hash, letting the salt be automatically generated
$hash = crypt($password);
?>
Example #3 Using crypt() with different hash types
<?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";
}
?>
Exemplul de mai sus va afișa ceva similar cu:
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
Note
Notă: There is no decrypt function, since crypt() uses a one-way algorithm.
add a note
User Contributed Notes
crypt
Matteo
18-May-2012 10:39
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