# CodeIgniter User Guide Version 2.1.0

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# Security Helper

The Security Helper file contains security related functions.

## Loading this Helper

This helper is loaded using the following code:

`$this->load->helper('security');`

The following functions are available:

## xss_clean()

Provides Cross Site Script Hack filtering. This function is an alias to the one in the Input class. More info can be found there.

## sanitize_filename()

Provides protection against directory traversal. This function is an alias to the one in the Security class. More info can be found there.

## do_hash()

Permits you to create SHA1 or MD5 one way hashes suitable for encrypting passwords. Will create SHA1 by default. Examples:

`$str = do_hash($str); // SHA1
$str = do_hash($str, 'md5'); // MD5`

Note: This function was formerly named `dohash()`, which has been deprecated in favour of `do_hash()`.

## strip_image_tags()

This is a security function that will strip image tags from a string. It leaves the image URL as plain text.

`$string = strip_image_tags($string);`

## encode_php_tags()

This is a security function that converts PHP tags to entities. Note: If you use the XSS filtering function it does this automatically.

`$string = encode_php_tags($string);`