This » PECL extension is not bundled with PHP. Information for installing this PECL extension may be found in the manual chapter titled Installation of PECL extensions. Additional information such as new releases, downloads, source files, maintainer information, and a CHANGELOG, can be located here: » http://pecl.php.net/package/crack.
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. A DLL for this PECL extension is currently unavailable. See also the building on Windows section.