Methods of protection of electronic documents against copying and editing

It is a little history

From the moment of the invention of writing the mankind began to transfer personal, state and universal secrets to suitable material carriers. As soon as ancestors did not exercise the wit in that texts were not read by others eyes. The most ancient and demanded method of protection by right is the cryptogram (in translation from Greek means "тайнопись"). For example, sacred Judaic texts were ciphered by a replacement method - instead of the first letter of the alphabet the last letter, instead of the second — penultimate, etc. was written. This ancient cipher is called Atbash^[1].

Also steps for protection of the transferred confidential messages against interception and substitution were taken. Usually for this purpose used armed security forces, but did not refuse and from alternative methods - frightened by God's anger and ancient damnations that was very efficient for those years.

People invented great variety of methods to protect paper documents from copying and editing (substitution). Part of them got over in "digit", and a part was thought up especially for protection of electronic documents.

Why to protect documents from copying and editing

Generally protection against copying and editing is required for working documents in the DOCX and PDF formats. The analytical agencies, design institutes and other companies offering information products report results of researches in the protected format to prevent unauthorized use and distribution. Also for business it is important to provide protection against substitution – for risk reduction it is necessary to guarantee that the document forever will remain in an invariable type.

However protection against copying and editing can be useful also for the personal purposes, for example, during creation of the book, a training course, rendering consulting services. So such functionality can be useful to everyone who develops intellectual products and wants to control their distribution.

Protection of the electronic documents DOC and PDF today

Marking

On the document it is possible to place information that it has a special status and it cannot be edited and copied. Sometimes marking is done imperceptible to identify "mole" - a leak source. In simple implementation the end in the document is put in different places and trace what option "will emerge". An improved version – use of the specialized hardware and software systems together with the MFP allowing to change intervals and a size of a font individually for each copy of the document. Such protection has reactive character, i.e. allows to identify the guilty person upon detection of an incident. Further we will look at the methods having pro-active character.

Password

The most widespread and a method available to all to protect electronic documents from unauthorized access consists in installation of the password on the document or archive. Usually it becomes the built-in tools of the program, for example, in the Acrobat application it is possible to limit editing, copying of contents and printing^[2]. But it is necessary to consider the following – the file can be copied and if to post the document protected thus and the password on the Internet, then everyone will be able easily to open it.

Access on a digital key (USB stick)

The method is based on presence at the user of a physical key (USB sticks or SD cards) for interpretation of the document. There is an USB stick – there is an access. So the file can be copied, but the copy cannot be opened without a certain material carrier. It solves a problem of unauthorized distribution, but with restrictions. First, the USB stick or the SD card costs money, and, secondly, it is necessary to provide delivery of this subject to the user that increases cost and complicates exchange of documents in a foreground mode. Thirdly, the user always should have this key at himself, and, fourthly, any equipment has property to break – and you will need to stipulate guarantee period and to provide replacement in case of breakdown.

Management system for access rights

Generally this method of protection of documents is used for corporate users based on service of management of the rights of the Active Directory (AD RMS). The documents protected by AD RMS are ciphered, and the author can set permissions for those who will get access to files. List of possible restrictions of the rights:

• Reading, change, printing.
• Document validity period.
• Prohibition of transfer of the e-mail.
• E-mail printing prohibition.

The combined methods of protection of documents

In all above-mentioned methods there are merits and demerits. Producers of the systems of protection of documents constantly work on connecting strengths in one solution. Ideal such combination seems:

• or to dictate providing a document access by the password which can be sent by e-mail by phone;
• binding to the unique material carrier, but that it was not necessary to buy and deliver in addition it to the end user;
• management of access rights on the Internet that it was possible to provide and withdraw file access in real time;
• display on the document of special tags for designation of a specific mode of distribution.

As the unique material carrier as a result it is possible to use the computer or the mobile device of the user, for example, the operating system and the processor have own serial numbers which cannot be forged. It will allow to control the number of copies of the protected document.

Management of access rights on the Internet provides DRM. During creation of the password access parameters are set: on how many devices it is possible to open the document, what is the time access will work whether it is possible to withdraw access quickly. At activation of the password all set restrictions begin to work.

Tags in itself do not provide protection, but allow to detect leak according to the digital fingerprint as for each user the unique combination of the digits and letters displayed on the document forms. Now in the market there are several professional solutions based on the combined methods for protection of electronic documents against copying and leak.

See Also:

• SFContent.com
• SFLetter.com

Notes