Steganography has been widely used for centuries. Here are some examples:  Hidden messages on paper written in secret inks. Hidden messages distributed, according to a certain rule or key, as smaller parts e. This particular form of steganography is called a null cipher.
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Steganography has been widely used for centuries. Here are some examples:  Hidden messages on paper written in secret inks. Hidden messages distributed, according to a certain rule or key, as smaller parts e. This particular form of steganography is called a null cipher. Messages written in Morse code on yarn and then knitted into a piece of clothing worn by a courier. Messages written on envelopes in the area covered by postage stamps.
In the early days of the printing press, it was common to mix different typefaces on a printed page because the printer did not have enough copies of some letters in one typeface. Thus, a message could be hidden by using two or more different typefaces, such as normal or italic.
A microdot camera During and after World War II, espionage agents used photographically-produced microdots to send information back and forth. Microdots were typically minute less than the size of the period produced by a typewriter.
World War II microdots were embedded in the paper and covered with an adhesive, such as collodion that was reflective and so was detectable by viewing against glancing light. Alternative techniques included inserting microdots into slits cut into the edge of postcards. She was a dealer in dolls , and her letters discussed the quantity and type of doll to ship. The stegotext was the doll orders, and the concealed "plaintext" was itself encoded and gave information about ship movements, etc.
Her case became somewhat famous and she became known as the Doll Woman. During World War II, photosensitive glass was declared secret[ by whom? Jeremiah Denton repeatedly blinked his eyes in Morse code during the televised press conference that he was forced into as an American prisoner-of-war by his North Vietnamese captors, spelling out "T-O-R-T-U-R-E".
In , crew members of the USS Pueblo intelligence ship, held as prisoners by North Korea , communicated in sign language during staged photo opportunities, to inform the United States that they were not defectors but captives of the North Koreans.
In other photos presented to the US, crew members gave " the finger " to the unsuspecting North Koreans, in an attempt to discredit photos that showed them smiling and comfortable. Digital messages[ edit ] Image of a tree with a steganographically hidden image.
The hidden image is revealed by removing all but the two least significant bits of each color component and a subsequent normalization. The hidden image is shown below. Image of a cat extracted from the tree image above.
Modern steganography entered the world in with the advent of personal computers being applied to classical steganography problems. The message to conceal is encrypted, then used to overwrite part of a much larger block of encrypted data or a block of random data an unbreakable cipher like the one-time pad generates ciphertexts that look perfectly random without the private key.
Mimic functions convert one file to have the statistical profile of another. This can thwart statistical methods that help brute-force attacks identify the right solution in a ciphertext-only attack. Concealed messages in tampered executable files, exploiting redundancy in the targeted instruction set.
Pictures embedded in video material optionally played at slower or faster speed. Injecting imperceptible delays to packets sent over the network from the keyboard.
Delays in keypresses in some applications telnet or remote desktop software can mean a delay in packets, and the delays in the packets can be used to encode data. Changing the order of elements in a set. Content-Aware Steganography hides information in the semantics a human user assigns to a datagram. Blog -Steganography. Messages are fractionalized and the encrypted pieces are added as comments of orphaned web-logs or pin boards on social network platforms.
In this case the selection of blogs is the symmetric key that sender and recipient are using; the carrier of the hidden message is the whole blogosphere. Modifying the echo of a sound file Echo Steganography.
Adaptive steganography: Skin tone based steganography using a secret embedding angle. On most systems, there is no visual difference from ordinary text. Some systems may display the fonts differently, and the extra information would then be easily spotted, of course.
Using hidden control characters, and redundant use of markup e. HTML pages can contain code for extra blank spaces and tabs at the end of lines, and colors, fonts and sizes, which are not visible when displayed. This may also be done with en space , figure space and whitespace characters. Various artists have used this method to conceal hidden pictures in their songs, such as Aphex Twin in Windowlicker or Nine Inch Nails in their album Year Zero.
The word "Wikipedia" is drawn using computer software 2. The image is converted into an audiofile 3. Finally the audio is analysed through a spectrogram, revealing the initial image Social steganography[ edit ] 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.
This relies on social context to make the underlying messages visible only to certain readers. Misspelling names or words that are popular in the media in a given week, to suggest an alternate meaning. Hiding a picture which can be traced by using Paint or any other drawing tool. In , Giannoula et al. In and , Yongfeng Huang and Shanyu Tang devised new steganographic algorithms that use codec parameters as cover object to realise real-time covert VoIP steganography.
However, specific techniques hide data in CPS components. A message, the plaintext , may be first encrypted by traditional means, producing a ciphertext. Then, an innocuous covertext is modified in some way so as to contain the ciphertext, resulting in the stegotext. For example, the letter size, spacing, typeface , or other characteristics of a covertext can be manipulated to carry the hidden message.
Only a recipient who knows the technique used can recover the message and then decrypt it. The ciphertext produced by most digital steganography methods, however, is not printable. Traditional digital methods rely on perturbing noise in the channel file to hide the message, and as such, the channel file must be transmitted to the recipient with no additional noise from the transmission.
Printing introduces much noise in the ciphertext, generally rendering the message unrecoverable. For instance, steganography using sudoku puzzles has as many keys as there are possible solutions of a sudoku puzzle, which is 6. SE of 2, in February This nomenclature was originally introduced by Krzysztof Szczypiorski in As a result, such methods can be harder to detect and eliminate.
These applications fall under the term inter-protocol steganography. However, some terms appear specifically in software and are easily confused. These are the most relevant ones to digital steganographic systems: The payload is the data covertly communicated. The carrier is the signal, stream, or data file that hides the payload, which differs from the channel, which typically means the type of input, such as a JPEG image. The resulting signal, stream, or data file with the encoded payload is sometimes called the package, stego file, or covert message.
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 between 0 and 1. In a set of files, the files that are considered likely to contain a payload are suspects. A suspect identified through some type of statistical analysis can be referred to as a candidate.
Countermeasures and detection[ edit ] Detecting physical steganography requires careful physical examination, including the use of magnification, developer chemicals and ultraviolet light. It is a time-consuming process with obvious resource implications, even in countries that employ many people to spy on their fellow nationals. However, it is feasible to screen mail of certain suspected individuals or institutions, such as prisons or prisoner-of-war POW camps. During World War II , prisoner of war camps gave prisoners specially-treated paper that would reveal invisible ink.
Kantrowitz describe in general terms the development of this paper. Three prototype papers Sensicoat, Anilith, and Coatalith were used to manufacture postcards and stationery provided to German prisoners of war in the US and Canada. If POWs tried to write a hidden message, the special paper rendered it visible. The US granted at least two patents related to the technology, one to Kantrowitz, U.
Patent 2,, , patented 20 July A similar strategy issues prisoners with writing paper ruled with a water-soluble ink that runs in contact with water-based invisible ink. In computing, steganographically encoded package detection is called steganalysis. The simplest method to detect modified files, however, is to compare them to known originals. For example, to detect information being moved through the graphics on a website, an analyst can maintain known clean copies of the materials and then compare them against the current contents of the site.
The differences, if the carrier is the same, comprise the payload. In general, using extremely high compression rates makes steganography difficult but not impossible.
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.
There are a variety of basic tests that can be done to identify whether or not a secret message exists. This process is not concerned with the extraction of the message, which is a different process and a separate step.
The most basic approaches of steganalysis are visual or aural attacks, structural attacks, and statistical attacks. These approaches attempt to detect the steganographic algorithms that were used. The size of the message that is being hidden is a factor in how difficult it is to detect.
The overall size of the cover object also plays a factor as well. If the cover object is small and the message is large, this can distort the statistics and make it easier to detect. A larger cover object with a small message decreases the statistics and gives it a better chance of going unnoticed.
Steganalysis that targets a particular algorithm has much better success as it is able to key in on the anomalies that are left behind. This is because the analysis can perform a targeted search to discover known tendencies since it is aware of the behaviors that it commonly exhibits. When analyzing an image the least significant bits of many images are actually not random.
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Part of the Lecture Notes in Computer Science book series LNCS, volume Abstract The abstract should summarize the contents of the paper and should Steganography is a technique to hide secret information in some other data we call it a vessel without leaving any apparent evidence of data alteration. All of the traditional steganographic techniques have limited information-hiding capacity. This is because the principle of those techniques was either to replace a special part of the frequency components of the vessel image, or to replace all the least significant bits of a multi-valued image with the secret information. Our new steganography uses an image as the vessel data, and we embed secret information in the bit-planes of the vessel.
A New Information Hiding Method Based on Improved BPCS Steganography
BPCS is a method to embed a message in an image by replacing all "complex" blocks of pixels in the image with portions of our message. It turns out that portions of the image with high complexity can be entirely removed or in this case, replaced with our message without changing the appearance of the image at all. Because most blocks of pixels are complex i. Below, the x image on the right contains the text of an entire novel, while still looking virtually identical to the vessel image on the left. It can be any file type, including another image.
BPCS-Steganography – Principle and Applications
A typical vessel is a color image having Red, Green, and Blue color components in a multi-bit data structure. The general scheme of steganography is shown in the other page where we will also refer to a file camouflage technique in brief. Eason in It can embed confidential information in vessel data which is typically a true color image bit BMP format and sometimes in an 8-bit indexed color image. Embedding actually, replacing is made on the bit-planes of the image. The most important feature of this steganography is that the embedding capacity is very large. The objective of this Web page is to show our novel technique to the people who are concerned about the Internet information security.
Diptee D. Lad, Prof. Sindhu M. We are the use of cryptographic and spreading sensitive information with outsiders. The method for steganographic techniques for hiding the data.