Protection against the threat of violation of confidentiality at the level of information content
There are various methods to protect the confidentiality of information at the content level.
Let's consider a situation where an attacker managed to gain access to the syntactic representation of confidential information, i.e. he has in front of him a sequence of characters of some language that satisfies the formal rules of notation. This situation may arise, for example, when it was possible to decrypt a data file and obtain a text that can be considered meaningful. In this case, various techniques can be used to conceal the true content of the message, the essence of which is that signs or words of another language are placed in accordance with one sequence of signs or words of one language.
As an example, we can cite the "Ave Maria" cipher, in the code version of which several words of explicit religious themes are assigned to each word, and sometimes to a phrase, as a result of which the message looks like a specific text of spiritual content. Common jargon can also illustrate the approaches used in everyday practice to conceal the true meaning of messages.
Another area of protection is the use of steganography. The word "steganography" literally means "cryptography" in Greek. It includes a huge variety of secret means of communication, such as invisible ink, microphotographs, conventional sign layout (used in signal agent communications), digital signatures, secret channels and means of communication on floating frequencies.
Markus Kuhn offers this definition: "Steganography is the art and science of organizing communication in a way that hides the actual presence of communication. Unlike cryptography, where the enemy has the ability to detect, intercept and decode messages - despite the fact that he is opposed by certain security measures guaranteed by a particular cryptosystem - steganography methods allow you to embed secret messages into harmless messages so that you cannot even suspect the existence of a subtext."
In relation to computer technology, it can be said that steganography uses methods of placing a message file in a "container" file, changing the "container" file in such a way that the changes made are almost invisible. Most of the computer steganographic techniques are combined by the methodology of changing the least Significant Bits (LSB), which is considered "noisy", i.e. having a random character in individual bytes of the "container" file.
In practice, in most cases, an open container does not contain useless data that can be used for modification. Instead, container files naturally contain different levels of noise, which on closer inspection, with the exception of the rest of the byte, can be an arbitrary value. An audio (.WAV) file, for example, contains mostly inaudible background noise at the LSB level; a 24-bit graphic image will contain color changes that are almost invisible to the human eye.
Effective protection against unauthorized access is possible only with a combination of various methods: organizational, technical, regulatory.
To block the channels of unauthorized access to information, it is of great importance to build identification and authentication systems that allow you to restrict access to protected information. Such systems are used both for physical access control (biometric authentication, authentication using a specific object) and for access control to resources and data (password systems).
Currently, cryptographic methods of protecting information from unauthorized access are the only reliable means of protection when transmitting information over communication channels. It is advisable to use cryptographic protection when storing information, which will allow, in combination with access restriction measures, to prevent unauthorized access to information.