Digital Download Protection & Secure Download Scripts
November 14th, 2007 | Web Development
A core feature of RandomClipart.com is the ability for customers to instantly download clipart files after checkout. My previous web development projects have taught me PHP, XHTML, CSS and MySQL and I’ve also had cause to integrate shopping carts with PayPal for tangible goods and services but I had no idea how to go about writing my own instant download script. A key requirement of any instant download script is security: original files must never be made accessible without a valid transaction. With so much at stake I didn’t want to risk writing my own script and making a costly mistake so I began to look for and review third-party digital download scripts and services.
The first option I looked at was an online service called PayLoadz. I’d come across this site quite a while before I’d even started planning RandomClipart.com and thought it’d be worth checking out again. A PayLoadz account comes with a fixed amount of secure server space for you to upload your files. Your products are then promoted on your own website before handing over to PayPal to complete checkout. A successful PayPal transaction triggers PayLoadz to email download links for purchased products to your customer, with copies and invoices for yourself. Download links are obviously hashed to protect the original files and prevent repeat downloads and link sharing.
At first glance PayLoadz seemed to be an ideal solution but on closer inspection there were a number of problems. Firstly RandomClipart.com is database driven and I didn’t want to be manually uploading new clipart to PayLoadz as and when it was made. Secondly the amount of disc space PayLoadz offers would at some point become restrictive and costly to upgrade. And lastly, but most importantly, I didn’t want to be giving away a slice of my income to someone for something that I could probably achieve myself, ableit with a third-party script.
Further searches turned up a script called DLGuard. DLGuard at the time of writing costs $127 for a double install licence and requires PHP and MySQL. Having read all about the features and checking the requirements I bought a copy and after a straight-forward installation (it comes with a Windows installer to install to your server from the desktop) began configuration. I have to say that DLGuard is an extremely well written and documented piece of software but after 30 minutes or so of playing around with the settings I began to realise this script wasn’t going to work for RandomClipart.com.
The main problem was that DLGuard supposes it’s creating an e-commerce site from your product database and even wants to handle the shopping cart and product pages for you. Although nearly everything is customisable with templates it became apparent that the secure download functionality I needed was only a fraction of what was on offer. Rather than cripple such a good piece of software to suit my limited needs I decided to ask for a refund, which was kindly paid in full, and look elsewhere for a simpler, bare bones script that I could fully integrate into my existing website.
Eventually I came across a script called LinkLok from VibraLogix. At the time of writing this script costs $29.95 for a single domain install and comes with one year’s support. The core of LinkLok consists of just one PHP file and comes in several different flavours depending on your payment processor. As I already have experience of PayPal integrations and a PayPal account I chose LinkLok for PayPal. The beauty of LinkLok is that you can make it as simple or as complicated as you like. Products can be defined in an array, a text file or a MySQL database and there are dozens of customisation options including link expiry, IP blocking and download limits. The documentation is extensive and provides step-by-step setup instructions, details of configuration options and notes on testing and troubleshooting. You can even test out the script by downloading the PDF manual from the website.
If you’re looking for a straight-forward, customisable PHP digital download script or link protector that can be easily integrated into your existing site to enable you to securely sell intangible goods I can thoroughly recommend LinkLok from Vibralogix.
