PHP, pass array through POST - php

Question

Which is the most secure way to send an array through POST?
foreach ($id as $array)
{
<input type="hidden" name="prova[]" value="<?php echo $array; ?>"/>
}
<input type="submit" name="submit"/>
or using implode() to create a single variable, pass the variable and then use explode() to get back the values into a new array?

Answer 1

Edit If you are asking about security, see my addendum at the bottom Edit
PHP has a serialize function provided for this specific purpose. Pass it an array, and it will give you a string representation of it. When you want to convert it back to an array, you just use the unserialize function.
$data = array('one'=>1, 'two'=>2, 'three'=>33);
$dataString = serialize($data);
//send elsewhere
$data = unserialize($dataString);
This is often used by lazy coders to save data to a database. Not recommended, but works as a quick/dirty solution.
Addendum
I was under the impression that you were looking for a way to send the data reliably, not "securely". No matter how you pass the data, if it is going through the users system, you cannot trust it at all. Generally, you should store it somewhere on the server & use a credential (cookie, session, password, etc) to look it up.

Answer 2

http://php.net/manual/en/reserved.variables.post.php
The first comment answers this.
<form ....>
<input name="person[0][first_name]" value="john" />
<input name="person[0][last_name]" value="smith" />
...
<input name="person[1][first_name]" value="jane" />
<input name="person[1][last_name]" value="jones" />
</form>
<?php
var_dump($_POST['person']);
array (
0 => array('first_name'=>'john','last_name'=>'smith'),
1 => array('first_name'=>'jane','last_name'=>'jones'),
)
?>
The name tag can work as an array.

Answer 3

You could put it in the session:
session_start();
$_SESSION['array_name'] = $array_name;
Or if you want to send it via a form you can serialize it:
<input type='hidden' name='input_name' value="<?php echo htmlentities(serialize($array_name)); ?>" />
$passed_array = unserialize($_POST['input_name']);
Note that to work with serialized arrays, you need to use POST as the form's transmission method, as GET has a size limit somewhere around 1024 characters.
I'd use sessions wherever possible.

Answer 4

There are two things to consider: users can modify forms, and you need to secure against Cross Site Scripting (XSS).
XSS
XSS is when a user enters HTML into their input. For example, what if a user submitted this value?:
" /><script type="text/javascript" src="http://example.com/malice.js"></script><input value="
This would be written into your form like so:
<input type="hidden" name="prova[]" value="" /><script type="text/javascript" src="http://example.com/malice.js"></script><input value=""/>
The best way to protect against this is to use htmlspecialchars() to secure your input. This encodes characters such as < into <. For example:
<input type="hidden" name="prova[]" value="<?php echo htmlspecialchars($array); ?>"/>
You can read more about XSS here: https://www.owasp.org/index.php/XSS
Form Modification
If I were on your site, I could use Chrome's developer tools or Firebug to modify the HTML of your page. Depending on what your form does, this could be used maliciously.
I could, for example, add extra values to your array, or values that don't belong in the array. If this were a file system manager, then I could add files that don't exist or files that contain sensitive information (e.g.: replace myfile.jpg with ../index.php or ../db-connect.php).
In short, you always need to check your inputs later to make sure that they make sense, and only use safe inputs in forms. A File ID (a number) is safe, because you can check to see if the number exists, then extract the filename from a database (this assumes that your database contains validated input). A File Name isn't safe, for the reasons described above. You must either re-validate the filename or else I could change it to anything.

Answer 5

Why are you sending it through a post if you already have it on the server (PHP) side?
Why not just save the array to s $_SESSION variable so you can use it when the form gets submitted, that might make it more "secure" since then the client cannot change the variables by editing the source.
It all depends on what you really want to do.