DMP
Protecting your online materials from cyber theft
The truth is, digital copyright is not the grey area some people would like to think it is. If you don't have permission from the author or publisher and you duplicate and/or repurpose images or text found on a website, it is highly likely that you're infringing their copyright. That said, many people do copy materials found on the web, because (a) it is so easy to do, and (b) so hard to police.
With that in mind, many web authors and publishers make use of one or more techniques to help protect their materials from cyber-theft. These methods may not fend off the most determined and knowledgeable cyber-thieves, but they do help to prevent the wider audience from making copies of materials that they simply do not have permission for. The same techniques could help you protect your images and documents.
The following is not an exhaustive list, but does illustrate the broad methods in use.
Protecting Images
| Javascript "NO RIGHT CLICK" | |
| Goal | To stop users from right-clicking on images and choosing "Save Picture as..." |
| Limits | The technique is rendered useless if browser javascript is disabled, or the browser otherwise ignores the script (eg. Opera). Screen-capturing will also not be defeated. |
| Examples | http://javascript.internet.com/page-details/no-right-click.html |
| Method | This is an example of scripting - the use of embedded code within your page to impede normal browser functionality. Other applications of scripting include the ability to:
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| Shrink-wrapping | |||||||
| Goal | To stop users' ability to right-click and save an image by putting a transparent gif over the image. When they save, all they get is a blank (transparent) image. | ||||||
| Limits | By exploring the source code, users can find the direct path to the source image and save. Screen-capturing (eg. Print Screen) will also not be defeated. | ||||||
| Example |
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| Method | Can be achieved with CSS/layers or with tables where the protected image is the cell background, and the content of the cell is a transparent gif, sized to match the cell. | ||||||
| Watermarking (Simple) | |||||||
| Goal | To utilise a visible watermark in the image, thus rendering the image unappealing and useless for repurposing. | ||||||
| Limits | Less aesthetically pleasing online images! | ||||||
| Example |
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| Method | If you're familiar with a graphics package like Photoshop or Fireworks, visible watermarking is something you can achieve yourself. For those not, reasonably priced software is available. iWatermark is a popular choice. |
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| Further info | http://www.scriptsoftware.com/iwatermark/ | ||||||
| Embedding copyright info | |||||||
| Goal | To embed visible copyright information in the image, thus notifying users of ownership and also rendering the image less appealing for repurposing. | ||||||
| Method | Similar to simple watermarking above, use your favourite graphics package to add a copyright layer. | ||||||
| Limits | The copyright information could easily be painted over or cropped by a determined thief, but the technique is as much about prevention rather than cure, in that users may think twice about stealing an obviously "copyrighted" image, and look elsewhere for an easier steal. | ||||||
| Example |
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| Watermarking (Digimarc) | |
| Goal | To attach an (almost) invisible watermark and other meta info (eg. copyright and authorship) to the image, without excessively degrading the visual quality of the image. |
| Limits | If you're serious about keeping your images protected, then this is the solution for you. Images can still be stolen but will be traceable. |
| Method | This technique is an embedded function of Adobe Photoshop. Using a Photoshop plugin from Digimarc you can add a virtually unnoticeable digital "noise" watermark. This watermark persists even through typical image editing and file format conversions. It is particularly useful for people who licence their work to others. Digimarc keep a register of authors/images. |
| Further info | In Photoshop choose Help > Photoshop Help... > Watermarks or visit http://www.digimarc.com/watermark/ *In addition to digital imagery, Digimarc's digital watermarking techniques can applied to audio, video and printed documents. |
| More Techniques / Summary | |
Other techniques worth exploring include:
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Protecting Text/Documents/Slides
| Javascript "NO RIGHT CLICK" | |
| Goal | To stop users from highlighting portions of text, right-clicking and choosing "Copy". |
| Limits | The technique is rendered useless if browser javascript is disabled, or the browser otherwise ignores the script (eg. Opera). |
| Examples | http://javascript.internet.com/page-details/no-right-click.html |
| Adobe PDFs | |
| Goal | To distribute documents or presentations which cannot be saved and/or printed and/or copied and/or edited and/or repurposed and/or opened without password. Adobe Acrobat has a comprehensive set of document security options: Screenshot 1, Screenshot 2 NB. It's not just MS Word documents that can be converted to PDF. PowerPoint presentations in a variety of formats (slides, handouts) can also be converted, so too Excel spreadsheets, and many other non-Microsoft file formats, including things like maps and diagrams. |
| Limits | There may be people out there who can 'hack' even secure PDFs. For example, Adobe themselves admit that some third-party alternatives to Adobe Acrobat do not support or respect security settings, and users of these products may be able to bypass restrictions you have set. The main limit though is one of accessibility. By distributing materials as PDFs you may be restricting access and use by legitimate users. PDFs are not necessarily as "accessible" to users with visual impairments using screen-reading software, as other types of documents. |
| More info | To learn more about Adobe PDF visit: To learn more about PDF document security refer to the Adobe Acrobat Help > Adding security to PDF Documents To explore the accessibility implications of using PDFs visit: |
Finally, a word of caution
It has been suggested, that the use of techniques to limit access to electronic materials, otherwise known as Technological Protection Methods (TPMs), may in fact do more harm than good; that their use can and does impede legitimate access. For example, our first technique above - No Right Click - is very annoying for users who use the context (right-click) menu in their browsing; using PDFs, can render some materials inaccessible for users with visual impairments.
The point continues to merit debate:
http://www.cippic.ca/en/projects-cases/election-2004/technological-protection.html
Matt Justice < mjustice@ryerson.ca>
Updated November 25, 2009
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