[FX.php List] Encrypting/decrypting in PHP

Stephen Grant stephen.grant at 724.com.au
Tue Sep 20 15:47:13 MDT 2011

The following is just one of the php encryption functions we use regularly. This particular set uses CAST_128 as the algorithym 
but that can be changed extremely easily.  If you use RJINDEL encryption then you can use Troi's plugin for decrypting directly in FileMaker.  However my preferred method is not to use a plugin in FileMaker at all but to use SSL to communicate with our web server for posting and returning encrypted content.

Of course  you can use the exact reverse of this to decrypt as well and the great thing is, its lightning quick.  We process somewhere in the neighborhood of 4-5 transactions per second 24 hours per day and it hardly moves the processor from idle.... 

We chose this method as our client (one of the four banks in Australia) required ultra secure communication and storage and this passed their own security requirements. 

Anyway, here's a snippet of the function. 

        function _encrypt($str) {
            $block = mcrypt_get_block_size('cast_128', 'cbc');
            $pad = $block - (strlen($str) % $block);
            $str .= str_repeat(chr($pad), $pad);

            return base64_encode(mcrypt_encrypt(MCRYPT_CAST_128, $key, $str, MCRYPT_MODE_CBC));

$str --> The string to be encrypted
$key --> the encryption key to set

The result of this encryption is a base64 encoded string that is simple to store in FileMaker.

You might also find it helpful to first JSON encode your data before passing it to be encrypted and then JSON decoding it on retrieval; it makes data management much easier. 

FYI there is a great website called www.tools4noobs.com that has an online ecryption/decription set that is very useful
for debugging encrypted matters.


----- Original Message -----
From: "Bob Patin" <bob at patin.com>
To: "FX.php Discussion List" <fx.php_list at mail.iviking.org>
Sent: Wednesday, 21 September, 2011 12:58:01 AM
Subject: Re: [FX.php List] Encrypting/decrypting in PHP


How do you decrypt when desired? In PHP or in FileMaker? 

Bob Patin 
Longterm Solutions LLC 
bob at longtermsolutions.com 
FileMaker 9, 10 & 11 Certified Developer 
Member of FileMaker Business Alliance and FileMaker TechNet 
Twitter: bobpatin 
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Expert FileMaker Consulting 
FileMaker Hosting for all versions of FileMaker 

On Sep 19, 2011, at 11:56 AM, Stephen Grant wrote: 

We do this all the time. Use: 


Then base64 encode the results. 

I will send an example tomorrow. 

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