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Steganography – Wikipedia
Here are some examples: For example, the hidden message may be in invisible ink between the visible lines of a private letter. The barely-visible dots contain encoded printer serial numbers and date and time stamps. Some modern computer printers use steganography, including Hewlett-Packard and Xerox brand color laser printers. The camera sensor, especially lower end sensors are not the best quality and can introduce some random bits.
The advantage of steganography over cryptography alone is that the intended secret message does not attract attention to itself as an object of scrutiny.
The simplest method to detect modified files, however, is to compare them to known originals. The difference between and in the value for blue intensity is likely to be undetectable by the human eye. Digital steganography output may be in the form of printed documents.
Generally though, there are many techniques known to be able to hide messages in data using steganographic techniques. Therefore, the least significant bit can be used more or less undetectably for something else other than color information. However, specific techniques hide data in CPS components.
Retrieved 11 February A similar strategy issues prisoners with writing paper ruled with a water-soluble ink that runs in contact with water-based invisible ink.
The change is so subtle that someone who is not specifically looking essteganografia it is unlikely to notice the change. In general, electronics that digitize an analog signal suffer from several noise sources, such as thermal noiseflicker noiseand shot noise.
However, it is feasible to screen mail of certain suspected individuals or institutions, such as prisons or prisoner-of-war POW camps. Patent 8, by estegannografia William Easttom Chuck Easttom. The hidden image is revealed by removing all but the two least significant bits of each color component and a subsequent normalization.
In early I realized that it was esteganografi to use zero-width characters, like zero-width non-joiner or other zero-width characters like the zero-width space to fingerprint text. There are distributed steganography methods,  including methodologies that distribute the payload through multiple carrier files in diverse locations to make detection more difficult.
Compression errors provide a hiding place for data, but high compression reduces the amount of data available to hold the payload, raising the encoding density, which facilitates easier detection in extreme cases, even by casual observation. Steganography has been widely used for centuries.
Esteganografia – – DocDroid
If the cover object is small and the message is large, this can distort the statistics and make it easier to detect. Institute of Telecommunications Seminar.
Retrieved 11 January Agent handling Field agent Non-official cover sockpuppet strawperson Official cover Resident spy. In communities with social or government taboos or censorship, people use cultural steganography—hiding messages in idiom, pop culture references, and other messages they share publicly and assume are monitored.
Detecting physical steganography requires careful physical examination, including the use of magnification, developer chemicals and estegqnografia light.
Generally, the hidden messages appear to be or to be part of something else: The hidden image is shown below. If POWs tried to write a hidden message, esteganogrxfia special paper rendered it visible.
The size of the message that is being hidden is a factor in how difficult it is to detect. Others, however, are resistant to estegankgrafia – or rather it is not possible to reliably distinguish data containing a hidden message from data containing just noise – even when the most sophisticated analysis is performed.
There must be redundancy. Invisible ink Polybius square Security engineering Semiotics Steganographic file system Etseganografia tools Audio watermark Security printing.
The overall size of the cover object also plays a factor as well. When analyzing an image the least significant bits of many images are actually not random. The proportion of bytes, samples, or other signal elements modified to encode the payload is called the encoding density and is typically expressed as a number esteganografiq 0 and 1.