It took time, energy and commitment for you to create an educational or entertainment document and you look forward to enjoying all the proceeds it will generate; this aspiration may remain to be an illusion if the document is unknowingly shared and copied. Where a document/s is not for commercial purposes but rather holds a company’s secrets, for it to land in the wrong hands would be simply catastrophic. Some form of PDF usage restriction in the form of encryption is therefore desired so that only authorized persons can access the document/s. DRM controls are further used to provide extra protection once the document is decrypted to control what the user can do with it.
One area of PDF usage concern is the making of unauthorized copies of documents for distribution purposes. PDF documents which are not meant for public use risk getting into the wrong hands if it is possible to make copies of them, and hence the first step in forestalling this is to disable the copy function. The second step is about wielding control over printing. Here we may think about controlling the number of prints that can be generated, discouraging sharing of printed material, or disabling printing altogether. We can discourage sharing of printed material by applying a watermark that associates the printing to a specific person, and simultaneously lowering the scan or photocopy quality. Watermarking is desired where printing may be required for operational reasons.
Another solution to controlling unauthorized PDF usage is disabling the save function. This means that the document cannot be saved in unprotected form to a computer or memory device for later printing, sharing, or modification. A key DRM function is to prevent save and save as functions by not making them available in the document viewing application. Some approaches to prevent save involve the use of plug-ins but this is not a good approach because for everything that one plug-in can do another can be designed to overturn the same function/s. The best way therefore to disable save is not having the code for this function available in the first place but since it is available in all PDF document viewing applications we need a special document viewer that doesn’t feature this function.
This special viewer can be tailored to not only prevent save and save as but also control printing capabilities, watermarking, copying and so forth, and thereby making it the ideal PDF usage control solution. Nonetheless, making your PDF documents to be only viewable through this special viewer cannot stop users from making use of the Windows File Explorer copy command to make copies of the original (encrypted) file. However, when you prevent save and save as functions you also in effect prevent the saving of the contents in an unprotected format, and as such any copies that will be made will also have DRM controls.
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Restricting Unauthorized PDF Usage