Crack Functions

XVI. Crack Functions


These functions allow you to use the CrackLib library to test the 'strength' of a password. The 'strength' of a password is tested by that checks length, use of upper and lower case and checked against the specified CrackLib dictionary. CrackLib will also give helpful diagnostic messages that will help 'strengthen' the password.

Note: This extension has been moved to the PECL repository and is no longer bundled with PHP as of PHP 5.0.0.


More information regarding CrackLib along with the library can be found at


This PECL extension is not bundled with PHP. Additional information such as new releases, downloads, source files, maintainer information, and a CHANGELOG, can be located here:

In PHP 4 this PECL extensions source can be found in the ext/ directory within the PHP source or at the PECL link above. In order to use these functions you must compile PHP with Crack support by using the --with-crack[=DIR] configuration option.

Windows users will enable php_crack.dll inside of php.ini in order to use these functions. In PHP 4 this DLL resides in the extensions/ directory within the PHP Windows binaries download. You may download this PECL extension DLL from the PHP Downloads page or at

Runtime Configuration

The behaviour of these functions is affected by settings in php.ini.

Table 1. Crack configuration options

crack.default_dictionaryNULLPHP_INI_PERDIRAvailable since PHP 4.0.5.
For further details and definitions of the PHP_INI_* constants, see the Appendix G.

Resource Types

This extension has no resource types defined.

Predefined Constants

This extension has no constants defined.


This example shows how to open a CrackLib dictionary, test a given password, retrieve any diagnostic messages, and close the dictionary.

Example 1. CrackLib example

// Open CrackLib Dictionary
$dictionary = crack_opendict('/usr/local/lib/pw_dict')
     or die(
'Unable to open CrackLib dictionary');

// Perform password check
$check = crack_check($dictionary, 'gx9A2s0x');

// Retrieve messages
$diag = crack_getlastmessage();
$diag; // 'strong password'

// Close dictionary

Note: If crack_check() returns TRUE, crack_getlastmessage() will return 'strong password'.

Table of Contents
crack_check -- Performs an obscure check with the given password
crack_closedict -- Closes an open CrackLib dictionary
crack_getlastmessage -- Returns the message from the last obscure check
crack_opendict -- Opens a new CrackLib dictionary
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