Question: I'm new to PHP, I started about 3 weeks ago.

I have a string, which is used with $\_POST to pass it to another page, the second page uses $\_GET to get these url and split it as desired.

My problem is that, in my first page I use a String, and I want to encrypt it, so that I can pass it as a plan text. In the second page I must decrypt it and get it as an array.

So is there any encryption method or function I can use which is compatible with $\_POST ( so I can send it to another page ) and decrypt it as an array ?

I need this method, because the second page is actually connecting to website and is a payment method. So i don't want users to manually edit the url and lower the amount of $ for the product they get.

tnx for your help.

Answer: 
You're thinking about this wrong. You NEVER trust information coming from the user's side.

For example, if your user sends a form that says what item they want, DO NOT include the price in the form. Instead, get the price from the server (database), where it can be trusted.
What you probably want to do is pass the contents of the users cart (i.e. the items he'd like to order) to the payment site.
Therefore, you should create a form like:

```
<form action="URL/to/paymentPage.php" method="post">
<!-- Item 1 -->
<input type="hidden" name="items[0]" value="productID1"/>
<input type="hidden" name="quantity[0]" value="quantity1"/>
<!-- Item 2 -->
<input type="hidden" name="items[1]" value="productID2"/>
<input type="hidden" name="quantity[1]" value="quantity2"/>
<!-- ... -->
<!-- Item n -->
<input type="hidden" name="items[n]" value="productIDn"/>
<input type="hidden" name="quantity[n]" value="quantityn"/>

<input type="submit" value="Order"/>
</form>

```

On the server in the file "URL/to/paymentPage.php" you can access the items using the following code:

```
<?php
$items = $_POST['items']; // Array of items ..
$quantities = $_POST['quantity']; // The array of quantities for each item ..

// Calculate the total price ..
$totalPrice = 0;
foreach($items as $idx => $itemID) {
  if($quantities[$idx]>0) {
    totalPrice += getPriceFromDB($itemID) * $quantities[$idx];
  }
}

echo 'Total Price to pay: '.$totalPrice;
?>

```

where the function getPriceFromDB actually retrieves the price for the item/product with the id $itemID from your database or elsewhere... :)

However, the user items are usually stored in the session, and, therefore, there is no need to submit the again.. ;)