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Revision as of 14:52, 29 December 2005 by imported>mutante
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Crypt is a string encoding function (hashing). It is used to encrypt passwords, for example in htaccess password files.

There are different implementations of the crypt function:

Unix Specification[edit]

crypt,Single UNIX ® Specification Crypt und Unix Passwörter (de)

crypt in Java[edit]

Java Implementations of Unix crypt Javascript crypt

PHP crypt -- One-way string encryption (hashing)

crypt in PHP[edit]

crypt() will return an encrypted string using the standard Unix DES-based encryption algorithm or alternative algorithms that may be available on the system. Arguments are a string to be encrypted and an optional salt string to base the encryption on. See the Unix man page for your crypt function for more information.

Multiple encryption types[edit]

On systems where the crypt() function supports multiple encryption types, the following constants are set to 0 or 1 depending on whether the given type is available:

CRYPT_STD_DES - Standard DES-based encryption with a two character salt

CRYPT_EXT_DES - Extended DES-based encryption with a nine character salt

CRYPT_MD5 - MD5 encryption with a twelve character salt starting with $1$

CRYPT_BLOWFISH - Blowfish encryption with a sixteen character salt starting with $2$ or $2a$

Note: There is no decrypt function, since crypt() uses a one-way algorithm.


Example 1. crypt() examples

$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

// Set the password
$password = 'mypassword';

// Get the hash, letting the salt be automatically generated
$hash = crypt($password);

Example 3. Using crypt() with different encryption types
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$07$rasmuslerd...........$') . "\n";

The above example will output something similar to:

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

See also md5() and the Mcrypt extension. 

from php.net/crypt

Source code to the Unix crypt() function

Using <crypt> on this wiki[edit]

You can use this Wiki to encrypt your passwords on the fly:


will return


The CryptExtension[edit]

the source for enabling this on Mediawiki is very simple,it just uses the PHP crypt function

# crypt mediawiki extension
# by mutante 18.03.2005

$wgExtensionFunctions[] = "wfCryptExtension";

function wfCryptExtension() {
global $wgParser;
$wgParser->setHook( "crypt", "renderCrypt" );

function renderCrypt( $input ) {

$input = mysql_escape_string($input);

$output=crypt('$input'); // http://www.php.net/crypt

return $output;

yep,nothing i really had to do by myself. mutante

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