A thorny question
A question that is frequently asked when specifying a new project is "how can I provide a file to our paid clients, without letting them distribute it to others?" The question is understandable - an ever-increasing number of companies have extensive digital assets, and in many cases the extent of these assets has outstripped the expertise to know how best to manage them.
The question that I end up asking in return is how they perceive their situation differing from that of major international music labels. A quick browse through the history of Digital Rights Management in music (read more) shows that the attempts of some of the world's wealthiest corporations to control their digital assets have largely failed. Ultimately, the problem is a human one.
A little knowledge
Thankfully, most of our clients have a slightly more controlled end-user base than Sony and EMI. So, how can the human aspects of the problem be addressed? Part of the issue is identifying whether you're dealing with carelessness / naivety or with malicious intent. One of our clients required a system which allowed confidential correspondence to be accessed and printed remotely from any web-enabled device: the end-users would be trusted figures, however they would rarely be trained in data security. Clearly, any system which allows printing is open to the Chrome "print to PDF" option, allowing it to be saved locally - and the best way to serve print-ready documents is to serve them as PDFs anyway, at which stage many browsers will download them to the local filesystem rather than display them in-browser.
There are solutions for releasing files in a controlled and secured manner - our accountants send our payroll using Egress Switch. This software allows you to view files on entering a password, and attempts to delete them all once the software is closed. However, despite all their technical wizardry, it's impossible to stop the end-user from copying the file elsewhere while it's open. It's a partial solution, and it works well for sending attachments over email, however it isn't a silver bullet.
At this stage, there is no substitute for good training. In our opinion, no amount of technological wizardry can replace a basic understanding of digital asset management. We have worked with our client on how to manage this across a disparate user base, and are reviewing the situation regularly as the application is upgraded.
A bird in the hand
Whether or not the initial distribution of a digital asset can be controlled, there are also ways of introducing end-user accountability into the mix. The most obvious of these is watermarking: a watermarked document, so long as it remains in its original form, can be tracked back to its source, provided that the watermark is unique on each copy. However, this does not prevent - for instance - copy-pasting large sections of text from a watermarked document and pasting them into an unprotected format. More advanced techniques are available: one such method that works well for text-based assets is known in the intelligence community as the "canary trap". Minor edits are made to uniquely identify each copy of an asset, and are placed in key areas of the text, such that they will almost certainly be copied when any significant portion of the document is reproduced. The edits link back to the original source, and again the end-user is accountable.
There's then a decision as to whether to let users know that you've got source tracking in place. Disclosing this scheme might encourage end-users not to share assets beyond their licence scope; however, it might also encourage users to find ways around it.
Ultimately, while it can be tempting to see technology solutions as a way to circumvent the risks of human involvement, the human aspect of any security setup is always a key factor to consider.
Got a question about the security of your setup? Get in touch.