Steganalysis

The steganalysis - formed as a portmanteau of steganography and analysis - focuses on the analysis and breaking steganographic method.

Demarcation for cryptanalysis

Using steganography to hide secret data using the cryptography secret data encrypted. The cryptanalysis deals accordingly with methods and techniques to extract information from encrypted texts. It is known that information is encrypted.

In contrast, only suspected in the steganalysis that in a carrier medium data are hidden. Therefore, first of all is not the reading of a hidden message the goal, but rather to show that there is a message at all. Looking at the data embedded in a carrier medium as a form of manipulation, the web analysis can be considered as a special case of multimedia forensics.

The web analysis makes use of evidence from the cryptanalysis.

Methods of steganalysis

In the steganalysis a message is suspected in a medium. The security of steganography based on the fact that third parties do not notice their use (confidentiality ). Another, but not obligatory point is that a recognized use of steganography is not automatically the readability of the message leads (Confidentiality ).

The steganalysis therefore goes in two steps:

Focus

Here there are several priorities:

Recognizability

When visibility steganographic information in a steganogram one assumes that an observed medium no message or steganographic embedding contains ( null hypothesis ). The alternative hypothesis, one is trying to prove, so is that there is a steganogram. As with usual statistical tests, the result is only an indicator that tells with a certain probability that the alternative hypothesis is true or not. Does not apply to them, but this is no proof that the medium is no secret information. Rather, the result will only indicates that it was not possible with the test carried out to demonstrate the use of steganographic methods. There is always the possibility that another test provides evidence.

The recognition is not dependent on the knowledge of the exact algorithm. In general, satisfy clearly categorized carrier media (test samples) in both steganographically modified and unmodified form, to perform appropriate tests.

Extraction

In the extraction of steganographic information information is obtained from the steganogram that were intended only for the recipient of the steganographic message. If an extraction is possible, the corresponding method is considered to be broken.

Digital watermarks

Bridge Analytical methods are also used in digital watermark. It is known that hidden information is included. In this variant of steganalysis tries to read the digital watermark from the media ( image, video or audio), to manipulate or delete it and leave the carrier medium may otherwise intact.

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