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steganography full report
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Steganography is the art and science of writing hidden messages in such a way that no one apart from the intended recipient knows of the existence of the message; this is in contrast to cryptography, where the existence of the message itself is not disguised, but the content is obscured. The advantage of steganography over cryptography alone is that messages do not attract attention to themselves, to messengers, or to recipients.
Steganographic messages are often first encrypted by some traditional means, and then a covertext is modified in some way to contain the encrypted message, resulting in stegotext. For example, the letter size, spacing, typeface, or other characteristics of a covertext can be manipulated to carry the hidden message; only the recipient (who must know the technique used) can recover the message and then decrypt it. Steganography uses in electronic communication include steganographic coding inside of a transport layer, such as an MP3 file, or a protocol, such as UDP.
The project 'Steganography' provides means for secure data transmission and secure data storage network. Hereby, important files carrying confidential information can be stored in the server in an encrypted form. Access to these files is limited to certain authorized people only. Transmission also takes place in an encrypted form so that no intruder can get any useful information from the original file during transit. Further, before trying to access important files, the user has to login to the system using a valid username and password, which is allotted to him by the system administrator.
Encryption is the process of encoding a message in such a way as to hide its contents. Modern Cryptography includes several secure algorithms for encrypting and decrypting messages. They are all based on the use of secrets called keys. A cryptographic key is a parameter used in an encryption algorithm in such a way that the encryption cannot be reversed without the knowledge of the key.
Fig 1.1 The Original Image 1.2 The modified image
The larger the cover message is (in data content terms ” number of bits) relative to the hidden message, the easier it is to hide the latter. For this reason, digital pictures (which contain large amounts of data) are used to hide messages on the Internet and on other communication media. It is not clear how commonly this is actually done. For example: a 24-bit bitmap will have 8 bits representing each of the three color values (red, green, and blue) at each pixel. If we consider just the blue there will be 28 different values of blue. The difference between say 11111111 and 11111110 in the value for blue intensity is likely to be undetectable by the human eye. Therefore, the least significant bit can be used (more or less undetectably) for something else other than color information. If we do it with the green and the red as well we can get one letter of ASCII text for every three pixels.
Stated somewhat more formally, the objective for making steganographic encoding difficult to detect is to ensure that the changes to the carrier (the original signal) due to the inject the payload (the signal to covertly embed) are visually (and ideally, statistically) negligible; that is to say, the changes are indistinguishable from the noise floor of the carrier.
Carrier File - A file which has hidden information inside of it. Steganalysis - The process of detecting hidden information inside of a file. Stego-Medium - The medium in which the information is hidden.
Redundant Bits - Pieces of information inside a file which can be overwritten or altered
with out damaging the file.
Payload - The information which is the be concealed.
The following formula provides a very generic description of the pieces of the steganographic process:
covermedium + hiddendata + stegokey = stegomedium
In this context, the covermedium is the file in which we will hide the hiddendata, which may also be encrypted using the stegokey. The resultant file is the stegomedium (which will, of course. be the same type of file as the covermedium). The covermedium (and, thus, the stegomedium) are typically image or audio files.
The project has the following objectives:
1. To create a tool that can be used to hide data inside a 24 bit color image.
2. The tool should be easy to use, and should use a graphical user interface.
3. The tool should work cross-platform.
4. The tool should effectively hide a message using an image degradation approach, and should be able to retrieve this message afterwards.
5. The tool should take into account the original content, to theoretically more effectively hide the message.
6. The tool should be able to provide some information as to the effectiveness of the hiding i.e. it should be able to evaluate the degradation of an image. The analysis used will consist of existing watermarking measures, re- implemented for this tool.
7. The technique should fall under the category of Secret Key Steganography -where without the key the hidden message cannot be retrieved.
8. The tool should be able to encrypt the message before embedding it.
Up until now, this has proven to be a successful steganographic technique for use in distributing spam and getting around my spam filtering software. At this point in time, spam filtering software is incapable of detecting the hidden content and categorizing the message as spam on the basis of that content. This success will probably be short lived, however
As mentioned above, cryptography is often used in situations where the existence of the message is clear, but the meaning of the message is obscured. In particular, the sender transforms the message into a form that (hopefully) only the intended recipient of the message can decrypt and read.Steganography is often used in situations where the actual existence of the message needs to be obscured.
The message can also be encrypted before it is hidden inside a cover message. This provides a double layer of protection. To begin with, encryption may make the existence of the message even more difficult to detect, due to the fact that some encryption techniques cause the patterns of the characters in the encrypted version to be more random than in the original version. In addition, even if the existence of the encrypted message is detected, it is unlikely that an eavesdropper will be able to read the message.
1. This program hides the message in the image by doing the following:
2. Reducing the message to the 64-character set beginning with the space character in the ASCII table. Each character can then be represented by six bits.
3. Decomposing each six-bit character into three groups of two bits each.
4. Replacing the two least-significant bits (LSB) in the red, green, and blue values for a given pixel by the three groups of two bits. Thus, each pixel can carry one six-bit character
Processor : Pentium III
Main memory:
Minimum : 64MB
Recommended : 128MB
Hard disk:
Minimum : 10.2GB
Recommended : 40GB
Clock Speed : 866 MHz
Virtual Memory : 32Bits
Cache memory : 512KB
Floppy disk drive : 1.44MB
Platform Used Tool used
: Java1.5 : NetBeans5.5
Steganographic Techniques used is oncealing data within encrypted data. The data to be concealed is first encrypted before being used to overwrite part of a much larger block of encrypted data. This technique works most effectively where the decrypted version of data being overwritten has no special meaning or use. Each pixel typically has three numbers associated with it, one each for red, green, and blue intensities, and these values often range from 0-255. Each number is stored as eight bits (zeros and ones), with a one worth 128 in the most significant bit (on the left), then 64, 32, 16, 8, 4, 2, and a one in the least significant bit (on the right) worth just 1.
Steganography strips less important information from digital content and injects hidden data in its place. This is done over the spectrum of the entire image. Here's one way it could be implemented:
The following sequence of 24 bits represents a single pixel in an image. Its 3 bytes of color information provide a total of 256 different values for each color (red, green and blue) and thus can represent a total of 16.7 million colors. This particular value displays as a dark green:
Table 5.1 Bytewise insertion of data
Byte 1 - Red Bytc2-Grcci Byte 3 - Blue
ODODOnn o onnonn o o onno
Now, let's take 11 of these pixels that represent, say, part of a solid-color background. In the following sequence, the least significant (rightmost) bit of each 8-bit byte has been co-opted to hide a text message”the four characters Aha!”in ASCII binary:
The hidden message occupies 32 of those 264 bits (about 12%) and contains four 8-bit bytes. In the diagram, each maroon or gold box represents a bit that had to be changed to include the hidden message. Notice that only 15 of 264 bits (less than 6%) had to be changed and only eight of the 11 pixels were altered.
The two figures below represent the 11 colored pixels we've been manipulating. The figure on the left is the original, unaltered version. The one on the right has been modified.
The DES (Data Encryption Standard) algorithm is the most widely used encryption algorithm in the world. For many years, and among many people, "secret code making" and DES have been synonymous. DES works on bits, or binary numbers--the 0s and 1s common to digital computers. Each group of four bits makes up a hexadecimal, or base 16, number. DES works by encrypting groups of 64 message bits, which is the same as 16 hexadecimal numbers. To do the encryption, DES uses "keys" where are also apparently 16 hexadecimal numbers long, or apparently 64 bits long. However, every 8th key bit is ignored in the DES algorithm, so that the effective key size is 56 bits. But, in any case, 64 bits (16 hexadecimal digits) is the round number upon which DES is organized.
The project consists of mainly four modules encryption, hide message, retrieve message and decryption. Encryption and hide message form the modules at the sender side. retrieve message and decryption form the modules at the receiver side
6.1.1 Encryption
Encryption includes a message or a file encrypting. Encryption involves converting the message to be hidden into a cipher text. Encryption can be done by passing a secret key.Secret key can be used for encryption of the message to be hidden.It provides security by converting it into a cipher text,which will be difficult for hackers to decrypt. Moreover if the message is password protected,then while retrieving message,the retriever has to enter the correct password for viewing the message.
6.1.2 Hide Message
Hiding message is the most important module of steganography.It involves embedding the message into the cover text. Each pixel typically has three numbers associated with it, one each for red, green, and blue intensities, and these values often range from 0-255.In order to hide the message,data is first converted into byte format and stored in a byte array.The message is then encrypted and then embed each bits into the LSB position of each pixel position. The least significant (rightmost) bit of each 8-bit byte has been co-opted to hide a text message.
6.2.1 Retrieve Message
It involves retrieving the embed message from the file independent of the file format. Once the message has been retrieved it has to be converted into original message or file.
This can be done by reading the embedded data from the master file. The read data will be in the bytes format. This message has to be converted into the suitable output file format.
6.2.2 Decryption
Decryption includes a message or a file decrypting. Decryption involves converting the cipher text into decrypted format. Decryption can be done by passing a secret key. Secret key can be used for decryption of the message that is hidden. It provides security by converting the cipher text, into the original data message or file . Moreover if the message is password protected, then while retrieving message, the retriever has to enter the correct password for viewing the message.
Java was developed at Sun Microsystems. Work on Java initially began with the goal of creating a platform-independent language and OS for consumer electronics. The original intent was to use C++, but as work progressed in this direction, developers identified that creating their own language would serve them better. The effort towards consumer electronics led the Java team, then known as First Person Inc., towards developing h/w and s/w for the delivery of video-on-demand with Time Warner.
Fig 7.1 Java 2 Platform,Standard Edition v 1.5
Unfortunately (or fortunately for us) Time Warner selected Silicon Graphics as the vendor for video-on-demand project. This set back left the First Person team with an
interesting piece of s/w (Java) and no market to place it. Eventually, the natural synergies of the Java language and the www were noticed, and Java found a market.
Today Java is both a programming language and an environment for executing programs written in Java Language. Unlike traditional compilers, which convert source code into machine level instructions, the Java compiler translates java source code into instructions that are interpreted by the runtime Java Virtual Machine. So unlike languages like C and C++, on which Java is based, Java is an interpreted language.
Java is the first programming language designed from ground up with network programming in mind. The core API for Java includes classes and interfaces that provide uniform access to a diverse set of network protocols. As the Internet and network programming have evolved, Java has maintained its cadence. New APIs and toolkits have expanded the available options for the Java network programmer.
In one of their early papers about the language, Sun described Java as follows: Java: A simple, object-oriented, distributed, interpreted, robust, secure, architecture neutral, portable, high-performance, multithreaded, and dynamic language. Sun acknowledges that this is quite a string of buzzwords, but the fact is that, for the most part, they aptly describe the language. In order to understand why Java is so interesting, let's take a look at the language features behind the buzzwords.
¦ Object-Oriented
Java is an object-oriented programming language. As a programmer, this means that you focus on the data in your application and methods that manipulate that data, rather than thinking strictly in terms of procedures. If you're accustomed to procedure-based programming in C, you may find that you need to change how you design your programs when you use Java. Once you see how powerful this new paradigm is, however, you'll quickly adjust to it. In an object-oriented system, a class is a collection of data and methods that operate on that data. Taken together, the data and methods describe the state and behavior of an object. Classes are arranged in a hierarchy, so that a subclass can inherit behavior from its super class. A class hierarchy always has a root class; this is a class with very general behavior. Java comes with an extensive set of classes, arranged in packages that you can use in your programs. For example, Java provides classes that create graphical user interface components (the java.awt package), classes that handle input and output (the package), and classes that support networking functionality
(the package). The Object class (in the java.lang package) serves as the root of the Java class hierarchy. Unlike C++, Java was designed to be object-oriented from the ground up. Most things in Java are objects; the primitive numeric, character, and Boolean types are the only exceptions. Strings are represented by objects in Java, as are other important language constructs like threads. A class is the basic unit of compilation and of execution in Java; all Java programs are classes. While Java is designed to look like C++, you'll find that Java removes many of the complexities of that language. If you are a C++ programmer, you'll want to study the object-oriented constructs in Java carefully. Although the syntax is often similar to C++, the behavior is not nearly so analogous. For a complete description of the object-oriented features of Java, The object oriented language used to create executable contents such as applications and applets.
¦ Interpreted
Java is an interpreted language: the Java compiler generates byte-codes for the Java Virtual Machine (JVM), rather than native machine code. To actually run a Java program, you use the Java interpreter to execute the compiled byte-codes. Because Java byte-codes are platform-independent, Java programs can run on any platform that the JVM (the interpreter and run-time system) has been ported to. In an interpreted environment, the standard "link" phase of program development pretty much vanishes. If Java has a link phase at all, it is only the process of loading new classes into the environment, which is an incremental, lightweight process that occurs at run-time. This is in contrast with the slower and more cumbersome compile-link-run cycle of languages
like C and C++.
¦ Architecture Neutral and Portable
Because Java programs are compiled to an architecture neutral byte-code format, a Java application can run on any system, as long as that system implements the Java Virtual Machine. This is a particularly important for applications distributed over the Internet or other heterogeneous networks. But the architecture neutral approach is useful beyond the scope of network-based applications. As an application developer in today's software market, you probably want to develop versions of your application that can run on PCs, Macs, and UNIX workstations. With multiple flavors of UNIX, Windows 95, and Windows NT on the PC, and the new PowerPC Macintosh, it is becoming increasingly difficult to produce software for all of the possible platforms. If you write your application in Java, however, it can run on all platforms. The fact that Java is interpreted and defines a standard, architecture neutral, byte-code format is one big part of being portable. But Java goes even further, by making sure that there are no "implementation-dependent" aspects of the language specification. For example, Java explicitly specifies the size of each of the primitive data types, as well as its arithmetic behavior. This differs from C, for example, in which an int type can be 16, 32, or 64 bits long depending on the platform. While it is technically possible to write non-portable programs in Java, it is relatively easy to avoid the few platform-dependencies that are exposed by the Java API and write truly portable or "pure" Java programs. Sun's new "100% Pure Java" program helps developers ensure (and certify) that their code is portable. Programmers need only to make simple efforts to avoid non-portable pitfalls in order to live up to Sun's trademarked motto "Write Once, Run Anywhere."
¦ Dynamic and Distributed
Java is a dynamic language. Any Java class can be loaded into a running Java interpreter at any time. These dynamically loaded classes can then be dynamically instantiated. Native code libraries can also be dynamically loaded. Classes in Java are represented by the Class class; you can dynamically obtain information about a class at run-time. This is especially true in Java 1.1, with the addition of the Reflection API. Java is also called a distributed language. This means, simply, that it provides a lot of high-level support for networking. For example, the URL class and Oar elated classes in the package make it almost as easy to read a remote file or resource as it is to read a local file. Similarly, in Java 1.1, the Remote Method Invocation (RMI) API allows a Java program to invoke methods of remote Java objects, as if they were local objects. (Java also provides traditional lower-level networking support, including datagram's and stream-based connections through sockets.) The distributed nature of Java really shines when combined with its dynamic class loading capabilities. Together, these features make it possible for a Java interpreter to download and run code from across the Internet. (As we'll see below, Java implements strong security measures to be sure that this can be done safely.) This is what happens when a Web browser downloads and runs a Java applet, for example. Scenarios can be more complicated than this, however. Imagine a multi-media word processor written in Java. When this program is asked to display some type of data that it has never encountered before, it might dynamically download a class from the network that can parse the data, and then dynamically download another class (probably a Java "bean") that can display the data within a compound document. A program like this uses distributed resources on the network to dynamically grow and adapt to the needs of its user.
¦ Simple
Java is a simple language. The Java designers were trying to create a language that a programmer could learn quickly, so the number of language constructs has been kept relatively small. Another design goal was to make the language look familiar to a majority of programmers, for ease of migration. If you are a C or C++ programmer, you'll find that Java uses many of the same language constructs as C and C++. In order to keep the language both small and familiar, the Java designers removed a number of features available in C and C++. These features are mostly ones that led to poor programming practices or were rarely used. For example, Java does not support the goto statement; instead, it provides labeled break and continue statements and exception handling. Java does not use header files and it eliminates the C preprocessor. Because Java is object-oriented, C constructs like struct and union have been removed. Java also eliminates the operator overloading and multiple inheritance features of C++. Perhaps the most important simplification, however, is that Java does not use pointers. Pointers are one of the most bug-prone aspects of C and C++ programming. Since Java does not have structures, and arrays and strings are objects, there's no need for pointers. Java automatically handles the referencing and dereferencing of objects for you. Java also implements automatic garbage collection, so you don't have to worry about memory management issues. All of this frees you from having to worry about dangling pointers, invalid pointer references, and memory leaks, so you can spend your time developing the functionality of your programs. If it sounds like Java has gutted C and C++, leaving only a shell of a programming language, hold off on that judgment for a bit, Java is actually a full-featured and very elegant language.
¦ Robust
Java has been designed for writing highly reliable or robust software. Java certainly doesn't eliminate the need for software quality assurance; it's still quite possible to write buggy software in Java. However, Java does eliminate certain types of programming errors, which makes it considerably easier to write reliable software. Java is a strongly typed language, which allows for extensive compile-time checking for potential type-mismatch problems. Java is more strongly typed than C++, which inherits a number of compile-time laxities from C, especially in the area of function declarations. Java requires explicit method declarations; it does not support C-style implicit declarations. These stringent requirements ensure that the compiler can catch method invocation errors, which leads to more reliable programs. One of the things that makes Java simple is its lack of pointers and pointer arithmetic. This feature also increases the robustness of Java programs by abolishing an entire class of pointer-related bugs. Similarly, all accesses to arrays and strings are checked at run-time to ensure that they are in bounds, eliminating the possibility of overwriting memory and corrupting data. Casts of objects from one type to another are also checked at run-time to ensure that they are legal. Finally, and very importantly, Java's automatic garbage collection prevents memory leaks and other pernicious bugs related to memory allocation and deallocation. Exception handling is another feature in Java that makes for more robust programs. An exception is a signal that some sort of exceptional condition, such as a "file not found" error, has occurred. Using the try/catch/finally statement, you can group all of your error handling code in one place, which greatly simplifies the task of error handling and recovery.
¦ Secure
One of the most highly touted aspects of Java is that it's a secure language. This is especially important because of the distributed nature of Java. Without an assurance of security, you certainly wouldn't want to download code from a random site on the Internet and let it run on your computer. Yet this is exactly what people do with Java applets every day. Java was designed with security in mind, and provides several layers of security controls that protect against malicious code, and allow users to comfortably run untrusted programs such as applets. At the lowest level, security goes hand-in-hand with robustness. As we've already seen, Java programs cannot forge pointers to memory, or overflow arrays, or read memory outside of the bounds of an array or string. These features are one of Java's main defenses against malicious code. By totally disallowing any direct access to memory, an entire huge, messy class of security attacks is ruled out.
The second line of defense against malicious code is the byte-code verification process that the Java interpreter performs on any untrusted code it loads. These verification steps ensure that the code is well-formed--that it doesn't overflow or underflow the stack or contain illegal byte-codes, for example. If the byte-code verification step was skipped, inadvertently corrupted or maliciously crafted byte-codes might be able to take advantage of implementation weaknesses in a Java interpreter. Another layer of security protection is commonly referred to as the "sandbox model": untrusted code is placed in a "sandbox," where it can play safely, without doing any damage to the "real world," or full Java environment. When an applet, or other untrusted code, is running in the sandbox, there are a number of restrictions on what it can do. The most obvious of these restrictions is that it has no access whatsoever to the local file system. There are a number of other restrictions in the sandbox as well. These restrictions are enforced by a Security Manager class. The model works because the entire core Java classes that perform sensitive operations, such as file system access, first ask permission of the currently installed Security Manager. If the call is being made, directly or indirectly, by untrusted code, the security manager throws an exception, and the operation is not permitted. Finally, in Java 1.1, there is another possible solution to the problem of security. By attaching a digital signature to Java code, the origin of that code can be established in a cryptographically secure and unforgettable way. If you have specified that you trust a person or organization, then code that bears the digital signature of that trusted entity is trusted, even when loaded over the network, and may be run without the restrictions of the sandbox model. Of course, security isn't a black-and-white thing. Just as a program can never be guaranteed to be 100% bug-free, no language or environment can be guaranteed 100% secure. With that said, however, Java does seem to offer a practical level of security for most applications. It anticipates and defends against most of the techniques that have historically been used to trick software into misbehaving, and it has been intensely scrutinized by security experts and hackers alike. Some security holes were found in early versions of Java, but these flaws were fixed almost as soon as they were found, and it seems reasonable to expect that any future holes will be fixed just as quickly.
¦ High-Performance
Java is an interpreted language, so it is never going to be as fast as a compiled language like C. Java 1.0 was said to be about 20 times slower than C. Java 1.1 is nearly twice as fast as Java 1.0, however, so it might be reasonable to say that compiled C code runs ten times as fast as interpreted Java byte-codes. But before you throw up your arms in disgust, be aware that this speed is more than adequate to run interactive, GUI and network-based applications, where the application is often idle, waiting for the user to do something, or waiting for data from the network. Furthermore, the speed-critical sections of the Java run-time environment, that do things like string concatenation and comparison, are implemented with efficient native code. As a further performance boost, many Java interpreters now include "just in time" compilers that can translate Java byte-codes into machine code for a particular CPU at run-time. The Java byte-code format was designed with these "just in time" compilers in mind, so the process of generating machine code is fairly efficient and it produces reasonably good code. In fact, Sun claims that the performance of byte-codes converted to machine code is nearly as good as native C or C++. If you are willing to sacrifice code portability to gain speed, you can also write portions of your program in C or C++ and use Java native methods to interface with this native code. When you are considering performance, it's important to remember where Java falls in the spectrum of available programming languages. At one end of the spectrum, there are high-level, fully-interpreted scripting languages such as Tcl and the UNIX shells. These languages are great for prototyping and they are highly portable, but they are also very slow. At the other end of the spectrum, you have low-level compiled languages like C and C++. These languages offer high performance, but they suffer in terms of reliability and portability. Java falls in the middle of the spectrum. The performance of Java's interpreted byte-codes is much better than the high-level scripting languages (even Perl), but it still offers the simplicity and portability of those languages.
¦ Multithreaded
In a GUI-based network application such as a Web browser, it's easy to imagine multiple things going on at the same time. A user could be listening to an audio clip while she is scrolling a page, and in the background the browser is downloading an image. Java is a multithreaded language; it provides support for multiple threads of execution (sometimes called lightweight processes) that can handle different tasks. An important benefit of multithreading is that it improves the interactive performance of graphical applications for the user. If you have tried working with threads in C or C++, you know that it can be quite difficult. Java makes programming with threads much easier, by providing built-in language support for threads. The java.lang package provides a Thread class that supports methods to start and stop threads and set thread priorities, among other things. The Java language syntax also supports threads directly with the synchronized keyword. This keyword makes it extremely easy to mark sections of code or entire methods that should only be run by a single thread at a time. While threads are "wizard-level" stuff in C and C++, their use is commonplace in Java. Because Java makes threads so easy to use, the Java class libraries require their use in a number of places. For example, any applet that performs animation does so with a thread. Similarly, Java does not support asynchronous, non-blocking I/O with notification through signals or interrupts--you must instead create a thread that blocks on every I/O channel you are interested in.
¦ Java Runtime Environment
The runtime environment used to execute the code. It is made up of the java language and java virtual machine. It is portable and it is platform neutral.
¦ Java tools
It is used by the developers to create java code. They include java compiler, java interpreter, classes, libraries and applet viewer.
¦ Java Application
Applications are programs written in java to carry out certain tasks on stand alone local computer. Execution of a stand alone program involves two steps.
Compiling the source code into byte code using javac.
Executing byte code program using java interpreter.
¦ Java Applets
Java applets are pieces of java code that are embedded in HTML document using the applet tag. When the browser encounters such code it automatically download it and execute it.
¦ Java Virtual Machine
It is a specification to which java codes must be written. All java code is to be compiled to be used in this nonexistent virtual machine. Writing the code which compiles in JVM ensures platform independence.
¢ Java is Robust
Robust programs are those reliable programs which are unlikely to fail even under the most unlikely conditions. Many languages like C do not have this feature because they are relaxed in terms of type checking in terms of programming errors. Java is strict about type declarations and does not allow automatic typecasting. Also it uses a pointer model that does not overwrite memory or corrupt data.
¢ Java is secure
Java allows creation of virus-free, tamper free systems to be created. It ensures security in the following ways.
Pointers and memory allocations are removed during compile time.
All byte codes are verified by the interpreter before executing.
All Java applets are treated as untrusted code executing in trusted environment.
Because Java was written to support distributed applications over the computer networks, it can be used with a variety of CPU and operating system architectures. To achieve this goal a compiler was created that produces architecture-neutral object files from Java code.
¢ Java is portable
Java byte code will be executed on any computer that has Java run time environment. The portability is achieved in the following ways.
Java primitive data types and the behavior of arithmetic operations on these data types are explicitly specified.
The Java libraries include portable interfaces for each platform on which the run time environment is available.
The entire Java system itself is portable.
¢ Java is small
Because java was designed to run on small computers, java system is relatively small for a programming language. It can run efficiently on PCs with 4 MB RAM or more. The java interpreter takes up only a few hundred kilo bytes.
¢ Java is garbage collected
Java programs don't have to worry about memory management. The Java system has a built in program called the garbage collector, which scans the memory and automatically frees the memory chunks that are not in use.
¢ Java is dynamic
Fundamentally distributed computer environments must be dynamic. Java is capable of dynamically linking new libraries, methods and instance variables as it goes without breaking and without concern.
A Java toolkit for developing graphical user interfaces (GUIs). It includes elements such as menus, toolbars and dialog boxes. Swing is written in Java and is thus platform independent, unlike the Java Abstract Window Toolkit (AWT), which provides platform-specific code. Swing also has more sophisticated interface capabilities than AWT and offers such features as tabbed panes and the ability to change images on buttons. Swing is included in the Java Foundation Classes (JFC) which is provided in the Java Developers
Toolkit (JDK).
Java applet or ap|) JvM fJFQ Operating system D livers #
AWT calls AWT
: High-level Ul functions, such as USER module in Windows or
Motif interface ill UNIX Low-level Ul functions, such .is the GDI module in Windows or
X. Window services in UNIX.

Swing calls C 5> Objects

Fig 7.2 Swings
Swing calls the operating system at a lower level than AWT. Whereas AWT routines use native code, Swing was written entirely in Java and is platform independent.
The Java Foundation Classes (JFC) is a graphical framework for building portable Java-based graphical user interfaces (GUIs). JFC consists of the Abstract Window Toolkit (AWT), Swing and Java 2D. Together, they provide a consistent user interface for Java programs, regardless whether the underlying user interface system is Windows, Mac OS X or Linux.
AWT is the older of the two interface libraries, and was heavily criticized for being little more than a wrapper around the native graphical capabilities of the host platform. That meant that the standard widgets in the AWT relied on those capabilities of the native widgets, requiring the developer to also be aware of the differences between host platforms.
An alternative graphics library called the Internet Foundation Classes was developed in more platform-independent code by Netscape. Ultimately, Sun merged the IFC with other technologies under the name "Swing", adding the capability for a pluggable look and feel of the widgets. This allows Swing programs to maintain a platform-independent code base, but mimic the look of a native application.
IO Streams
Most programs use data in one form or another, whether it is as input, output, or both. The sources of input and output can vary between a local file, a socket on the network, a database, variables in memory, or another program. Even the type of data can vary between objects, characters, multimedia, and others.
Data for a program may come from several sources. Data created by a program may be sent to several destinations. The connection between a program and a data source or destination is called a stream. An input stream handles data flowing into a program. An output stream handles data flowing out of a program.
Fig 7.3 Data handling
The Java Development Kit (JDK) provides APIs for reading and writing streams of data. These APIs have been part of the core JDK since version 1.0, but are often overshadowed by the more well-known APIs, such as JavaBeans, JFC, RMI, JDBC, and so on. However, input and output streams are the backbone of the JDK APIs.
To bring data into a program, a Java program opens a stream to a data source, such as a file or remote socket, and reads the information serially. On the flip side, a program can open a stream to a data source and write to it in a serial fashion. Whether you are reading from a file or from a socket, the concept of serially reading from, and writing to different data sources is the same.
Prior to JDK 1.1, the input and output classes (mostly found in the package) only supported 8-bit byte streams. The concept of 16-bit Unicode character streams was introduced in JDK 1.1. While byte streams were supported via the and classes and their subclasses, character streams are implemented by the and classes and their subclasses.
Most of the functionality available for byte streams is also provided for character streams. The methods for character streams generally accept parameters of data type char parameters, while byte streams, you guessed it, work with byte data types. The names of the methods in both sets of classes are almost identical except for the suffix, that is, character-stream classes end with the suffix Reader or Writer and byte-stream classes end with the suffix Input Stream and Output Stream. For example, to read files using character streams, you would use the class; for reading it using byte streams you would use
Unless you are working with binary data, such as image and sound files, you should use readers and writers.
> Multithreading
Multitasking is performing two or more tasks at the same time. Nearly all operating systems are capable of multitasking by using one of two multitasking techniques: process-based multitasking and thread-based multitasking.
Process-based multitasking is running two programs concurrently. Programmers refer to a program as a process. Therefore, you could say that process-based multitasking is program-based multitasking.
Thread-based multitasking is having a program perform two tasks at the same time. For example, a word processing program can check the spelling of words in a document while you write the document. This is thread-based multitasking.
A good way to remember the difference between process-based multitasking and thread-based multitasking is to think of process-based as working with multiple programs and thread-based as working with parts of one program.
The objective of multitasking is to utilize the idle time of the CPU. Think of the CPU as the engine of your car. Your engine keeps running regardless of whether the car is moving. Your objective is to keep your car moving as much as possible so you can get the most miles from a gallon of gas. An idling engine wastes gas.
The same concept applies to the CPU in your computer. You want your CPU cycles to be processing instructions and data rather than waiting for something to process. A CPU cycle is somewhat similar to your engine running.
It may be hard to believe, but the CPU idles more than it processes in many desktop computers. Let's say that you are using a word processor to write a document. For the most part, the CPU is idle until you enter a character from the keyboard or move the mouse. Multitasking is designed to use the fraction of a second between strokes to process instructions from either another program or from a different part of the same program.
Making efficient use of the CPU may not be too critical for applications running on a desktop computer because most of us rarely need to run concurrent programs or run parts of the same program at the same time. However, programs that run in a networked environment, such as those that process transactions from many computers, need to make a CPU's idle time productive.
The package provides a powerful and flexible infrastructure for networking. provides the classes for implementing networking applications. Using the socket classes, you can communicate with any server on the Internet or implement your own Internet server. A number of classes are provided to make it convenient to use Universal Resource Locators (URLs) to retrieve data on the Internet.
Fig 7.4 The classes of java.netpackage
Sender side 1
Receiver side
Fig 8.1 Level 0: DFD
Fig 8.2 Level 1:Embedding information in a file
Fig 8.3 Level 2 : Retrieving original information
Encrypted Message / file
Encrypted Message/file-
Fig 8.4 Level 3 : Steganography
Fig 9.1 Login Form
Fig 9.3 Window for decoding.
Fig 9.6 Retrieved message from master file.
Embedding file - Stego Magic 2.0.0 Q[n][x
Fig 9.7 Embedding a file in a master file.
Fig 9.8 Retrieved file from the master file.
The main features of Steganography are:
1. Messages do not attract attention to themselves.
2. The tool should be easy to use, and should use a graphical user interface.
3. The tool works cross-platform.
4. Small file distortions after hiding information.
5. It is possible to extract info after it has been compressed.
6. Information is protected with password
7. Unique.
The advantages of Steganography are:
1. It provides a better security for the sharing of data in local area network.
2. Important files carrying confidential information can be stored in the server in an encrypted form.
3. Using public key or private key can encrypt files.
4. No intruder can get any useful information from the original file during transmit.
5. It provides a better-secured data storage and transmission both at the system level and network level.
The limitations of Steganography are:
1. It provides the storing of data in an unprotected mode.
2. Password leakage may occur and it leads to the unauthorized access of data.
3. The intruders will affect stegos.
In the area of communication revolution, information has been an inevitable component. The attraction of web services is simplicity, firewall neutrality and lack of dependency on the implementation technology at the service end.
Efficient computing capabilities are therefore utilized. The availability of the required information at the press of a button is something favourable and therefore computers are used for this purpose. Thus, one way of potential taping is achieved.
The project "Steganography" after being tested and was found to be achieving what is meant for. But this system never provides a full proof solution for all their problems in the user point of view. The system is found to be 100% error free and ready for implementation.
The system has been designed in such a way that it can be modified with very little effort when such a need arises in the future. The system has been found to work efficiently and effectively. Due to its higher user friendliness, others may use these documents as a prototype for developing similar application.
Future enhancements and plans which are envisioned for the system are the following:
1. The development of a system that will utilize the Steganographic Obliterator on incoming and email messages and attachments.
2. Investigate the feasibility of embedding the program in firewalls to act as a first line of
defense against steganographic data transmission.
3. Expand the steganographic algorithm attack method beyond the least significant
bits using some other techniques.
1. http://www.jjtcsteganography
2. en .wikipediawiki/steganography
3. http://www.garykesslerlibrary/steganography.html
5. http://www.attackpreventioncryptology/steganography
6. Hilbert Schildt (2002) Java 2: The Complete Reference.Fifth Edition
7. William Stallings (2003) Cryptography and network security principle and practice
Post: #2

.doc  STEGNOGRAPHY.doc (Size: 75.5 KB / Downloads: 649)

Steganography comes from the Greek and literally means, "Covered writing". It is one of various data hiding techniques, which aims at transmitting a message on a channel where some other kind of information is already being transmitted. This distinguishes steganography from covert channel techniques, which instead of trying to transmit data between two entities that were unconnected before.
The goal of steganography is to hide messages inside other harmless messages in a way that does not allow any enemy to even detect that there is a second secret message present. The only missing information for the enemy is the short easily exchangeable random number sequence, the secret key, without the secret key, the enemy should not have the slightest chance of even becoming suspicious that on an observed communication channel, hidden communication might take place.
Steganography is closely related to the problem of hidden channels n secure operating system design, a term which refers to all communication paths that cannot easily be restricted by access control mechanisms. In an ideal world we would all be able to sent openly encrypted mail or files to each other with no fear of reprisals. However there are often cases when this is possible, either because the working company does not allow encrypted email or the local government does not approve of encrypt communication (a reality in some parts of the world). This is where steganography can come into play.
Data hiding techniques can also be classified with respect to the extraction process:
Cover Escrow methods need both the original piece of information and the encoded one in order to extract the embedded data.
Blind or Oblivious schemes can recover the hidden message by means only of the encoded data.
Steganography has developed a lot in recent years, because digital techniques allow new ways of hiding informations inside other informations, and this can be valuable in a lot of situations. The first to employ hidden communications techniques -with radio transmissions- were the armies, because of the strategic importance of secure communication and the need to conceal the source as much as possible.
Nowadays, new constraints in using strong encryption for messages are added by international laws, so if two peers want to use it, they can resort in hiding the communication into casual looking data. This problem has become more and more important just in these days, after the international Wassenaar agreement, with which around thirty of the major - with respect to technology - countries in the world decided to apply restrictions in cryptography export similar to the USâ„¢s ones.
Another application of steganography is the protection of sensitive data. A file system can be hidden in random looking files in a hard disk, needing a key to extract the original files. This can protect from physical attacks to people in order to get their passwords, because maybe the attacker canâ„¢t even know that some files are in that disk.
The major concern of steganography is stealth, because if an attacker, either passive or active, can detect the presence of the message, from that point he can try to extract it and, if encrypted, to decrypt it. The resistance to attempt at destruction or noise is not required, since we consider the sender and the receiver equally interested in exchanging messages, so that they will try to transmit the stego-medium in the best way they can. If the stego-data can be transmitted over the selected channel, and this is usually the case with all the media that are used, like images or sounds, then the embedded data will be preserved along with them. Thus, data hiding techniques for steganography must focus on the maximum strength against detection and extraction.
As a second request, we would prefer a high data rate, because we will usually want to be able to exchange any amount of data, from simple messages to top secret images.
Steganography and cryptography are cousins in spy-craft family. Cryptography scrambles a message so it cannot be understood. Steganography hides the message so it cannot be seen. A message in cipher text for instance might arouse suspicion on the part of the recipient while an invisible message created with steganographic methods will not.
In this way, we can say that steganography completes cryptography, and actually there are usually two ciphers to break when trying to extract the embedded message: one is the one with which the message was embedded, and the other is the one with which the message was enciphered.
Some history
The first description of the use of steganography dates back to the Greeks. Herodotus tells how a message was passed to the Greeks about Xersesâ„¢ hostile intentions underneath the wax of a writing tablet, and describes a technique of dotting successive letters in a cover text with a secret ink, due to Aeneas the Tactician.
Pirate legends tell of the practice of tattooing secret information, such as a map, on the head of someone, so that the hair would conceal it.
Kahn tells of a trick used in China of embedding a code ideogram at a prearranged position in a dispatch; a similar idea led to the grille system used in medieval Europe, where a wooden template would be placed over a seemingly innocuous text, highlighting an embedded secret message.
Invisible ink offered a common form of invisible writing. Early in WWII, steganographic technology consisted almost exclusively of these inks. With invisible ink, a seemingly innocent letter could contain a very different message written between the lines.
During WWII the grille spies used method or some variants. In the same period, the Germans developed microdot technology, which prints a clear, good quality photograph shrinking it to the size of a dot.
During the "Cold War" period, USSR and US wanted to hide their sensors in the enemyâ„¢s facilities. These devices had to send data to their nations, without being spotted.

We give some definitions common to the steganography field:
Cover medium: This is the medium in which we want to hide data, it can be an innocent looking piece of information for steganography, or some important medium that must be protected for copyright or integrity reasons.
Embedded message: This is the hidden message we want to put in the cover. It can be some data for steganography and some copyright informations or added content for digital watermarking.
Stegokey: This is represented by some secret information, which is needed in order to extract the embedded message from the stego-medium
Stego-medium: This is the final piece of information that the casual observer can see.
We can define this simple formula:
Cover-medium + embedded-message = stego-message
To a computer, an image is an array of numbers that represent an array of numbers that represent light intensities at various points or pixels. These pixels make up the imageâ„¢s raster data. A common image size is 640 * 480 and 256 colors (or 8 bits per pixel). Such an image could contain about 300 kb of data.
Digital images ate typically stored as either 24-bit or 8-bit files. A 24-bit image provides the most space for hiding information, however, it can be quite large except for the JPEG images. A 24-bit image of 1,024 pixels width and 768 pixels height has more than two million pixels, each having 24-bits, which would produce a file exceeding 2 Mega bytes. Such a file would attract attention during transmission. File compression would thus be beneficial, if not necessary, to transmit such a file.
File compression
There are two types of file compression methods- lossless and lossy. Both methods save storage space but have different results, interfer9ing with the hidden information, when information is uncompressed. Lossless compression lets us reconstruct the original message exactly; therefore it is preferred when the original information must remain intact (as with steganographic images). Lossless compression us typical of mages saved as GIF and 8-bit BMP.
Lossless compression, on the other hand, saves space but may not maintain the original imageâ„¢s integrity. This method typifies images saved as JPEG. Due to the lossy compression algorithm, which we discuss later, the JPEG formats provide close approximations to high-quality digital photographs but not an exact duplicate. Hence the term lossy compression.
Embedding data
Embedding data, which is to be hidden, into an image requires two files. The first is the innocent looking image that will hold the hidden information, called the cover image. The second file is the message- the information to be hidden. A message may be plain text, cipher text, other images, or anything that can be embedded in a bit stream, when combined, the cover image and the embedded message make a stego- image. A stego-key (a type of password) may also be used to hide, and then later decode, the message.
Most steganographic software neither supports not recommends using JPEG mages. But recommends instead the use of lossless 24-bit images such as BMP. The next best alternative to 24-bit images is 256- color or gray scale images. The most common of these found on the Internet are GIF files.
In 8-bit color images such as GIF files, each pixel is represented by a single byte, and each pixel nearly points to a color index table (a palette) with 256 possible colors. The pixels value is between 0 and 255. The software simply paints the indicated color on the screen at the selected pixel position.
Many steganography experts recommend the use of images featuring 256 shades of grapy. Gray scale images are preferred because the shades change very gradually from byte to byte, and the less the value changes between palette entries, the better they can hide information.
When considering an image in which to hide information, you must consider the image as well as the palette. Obviously, an image with large areas of solid colors is a poor choice, as variances created from the embedded massage will be noticeable in the solid areas.
Information can be hidden many different ways in images. To hide information, straight message insertion may encode every bit of information in the message or selectively embed the message in noisy areas that draw less attention- those areas where there is a great deal of natural color variation. The message may also be scattered randomly throughout the image. Redundant pattern encoding wallpapers the cover image with the message.
A number of ways exist to hide information in digital images. Common approaches include:
Least significant bit (LSB) insertion.
Masking and filtering.
Algorithms and transformations.
Least significant bit insertion
Least significant Bit insertion is a common, simple approach to embedding information in a cover file. To hide an image in the LSBs of each byte of a 24-bit image, you can store 3 bits in each pixel. A 1,024 * 768 image has the potential to hide a total of 2,359,296 bits of information. Ti you compress the message to be hidden before you embed it, you can hide a large amount of information. To the human eye, the resulting stego-image will look identical to the cover image.
Masking and Filtering
Masking and filtering techniques, usually restricted to 24-bit and tray-scale images, hide information by marking an image, in a manner similar to paper watermarks. Watermarking techniques may be applied without fear of image destruction due to lossy compression because they are more integrated into the image.
Visible watermarks are not steganography by definition. The difference is primarily one of intent. Traditional steganography conceals information; watermarks extend information and become an attribute of the cover image. Digital watermarks may include such information as copyright, ownership, or license. In steganography, the object of communication is the hidden message. In digital watermarking, the object of communication is the cover.
To create a watermarked image, we increase the luminance of the masked area by 15 percent. If we were to change the luminance by a smaller percentage, the mask would be undetected by the human eye. Now we can use the watermarked image to hide plaintext or encoded information.
Masking is more robust than LSB insertion with respect to compression, cropping and some image processing. Masking techniques embed information in more significant areas so that the hidden message is more integral to the cover image than just hiding it in the noise level. This makes it more suitable than LSB with lossy JPEG images.
Algorithms and Transformations
LSB manipulation is a quick and easy way to hide information but is vulnerable to small changes resulting from image processing or lossy compression. Such compression is a key advantage that JPEG images have over other formats. High quality images can be stored in relatively small files using JPEG compression method.
One steganographic method that integrates the compression algorithm for hiding the information is Jpeg-Jsteg.
Jpeg-Jsteg creates a JPEG stego image from the input of a message to be hidden and a lossless cover mage.
Another method used in Patchwork and similar techniques is the redundant pattern encoding. Here the hidden information is scattered throughout the cover mage. These approaches may help protect against image processing such as cropping and rotations and they hide information more thoroughly than by simply masking. They also support image manipulation more readily than tools that rely on LSB. In using redundant pattern encoding, you must trade off message size against robustness. A large message may be embedded only once because it would occupy a much greater portion of the image area.
Other techniques encrypt and scatter the hidden data throughout an image. Scattering the message makes it appear more like noise. Proponents of this approach assume that even if the message bits are extracted, they will be useless without the algorithm and stego-key to decode them.
Scattering and encryption helps protect against hidden message extraction but not against message destruction through image processing. A scattered message in the imageâ„¢s LSBs is still as vulnerable to destruction from lossy compression and mage processing, as is a clear text message inserted n the LSBs.
Technique basics
Today, when converting an analog image to digital format, we usually choose between three different ways of representing colors:
24-bit color: every pixel can have one in 2^24 colors, and these are represented as different quantities of three basic colors: red ®, green (G), blue (B), given by 8 bits (256 values) each.
8-bit color: every pixel can have one in 256 (2^8) colors, chosen from a palette, or a table of colors.
8-bit gray-scale: every pixel can have one in 256 (2^8) shades of gray.
LSB insertion modifies the LSBs of each color in 24-bit images, or the LSBs of the 8-bit value for 8-bit images.
Data Rate
The most basic of LSBs insertion for 24-bit pictures inserts 3 bits/pixel. Since every pixel is 24 bits, we can hide
3 hidden-bits/pixel / 24 data-bits/pixel = 1/8 hidden-bits/data-bits.
So for this case we hide 1 bit of the embedded message for every 8 bits of the cover image.
If we pushed the insertion to include the second LSBs, the formula would change to:
6 hidden-bits/pixel / 24 data-bits/pixel = 2/8 hidden-bits/data-bits
And we would hide 2 bits of the embedded message for every 8 bits of the cover image.
Adding a third-bit insertion, we would get:
9 hidden-bits/pixel / 24 data-bits/pixel = 3/8 hidden-bits/data-bits
Acquiring a data rate of 3 embedded bits every 8 bits of the image. The data rate for insertion in 8-bit images is analogous to the 1 LSB insertion in 24-bit images, or 1 embedded bit every 8 cover bits. We can see the problem in another light, and ask how many cover bytes are needed to send an embedded byte.
For 1-LSB insertion in 24-bit images or in 8-bit images this value would be 8/1*8 = 8 Bytes. For 2-LSBs insertion in 24-bit pictures it would be 8/2*8 = 4 Bytes, for 3-LSBs insertion it would be 8/3*8 = 21.33 Bytes.
LSB insertion is very vulnerable to a lot of transformations, even the most harmless and usual ones. Lossy compression, e.g. JPEG, is very likely to destroy it completely. The problem is that the "holes" in the Human Visual System that LSB insertion tries to exploit - little sensitivity to added noise - are the same that lossy compression algorithms rely on to be able to reduce the data rate of images. Geometrical transformations, moving the pixels around and especially displacing them from the original grid, are likely to destroy the embedded message, and the only one that could allow recovery is a simple translation. Any other kind of picture transformation, like blurring or other effects, usually will destroy the hidden data. All in all, LSB insertion is a very little robust technique for data hiding.
Ease of detection/extraction
There is no theoretical outstanding mark of LSB insertion, if not a little increase of background noise.
Itâ„¢s very easy, instead, to extract LSBs even with simple programs, and to check them later to find if they mean something or not.
Suitability for steganography or watermarking
First of all, since it is a so vulnerable technique even for simple processing, LSB insertion is almost useless for digital watermarking, where it must face malicious attempts at its destruction, plus normal transformations like compression/decompression or conversion to analog (printing or visualization)/conversion to digital (scanning).
Its comparatively high data rate can point it as a good technique for steganography, where robustness is not such an important constraint.
Problems and possible solutions
Having stated that LSB insertion is good for steganography, we can try to improve one of its major drawbacks: the ease of extraction. We donâ„¢t want that a malicious attacker be able to read everything we are sending.
This is usually accomplished with two complementary techniques:
Encryption of the message, so that who extracts it must also decrypt it before it makes sense.
Randomizing the placement of the bits using a cryptographical random function (scattering), so that itâ„¢s almost impossible to rebuild the message without knowing the seed for the random function.
In this way, the message is protected by two different keys, acquiring much more confidentiality than before. This approach protects also the integrity of the message, being much more difficult (we could say at least computationally infeasible) to counterfeit the message.
Anyway, since we donâ„¢t want our message to be only an encrypted and scrambled message, we must go back to the purpose of making the communication hidden.
The two most important issues in this problem are:
The choice of images
The choice of the format (24-bit or 8-bit, compressed or not)
The cover image first of all must seem casual, so it must be chosen between a set of subjects that can have a reason to be exchanged between the source and the receiver. Then it must have quite varying colors, it must be "noisy", so that the added noise is going to be covered by the already present one. Wide solid-color areas magnify very much any little amount of noise added to them. Second, there is a problem with the file size, which involves the choice of the format. Unusually big files exchanged between two peers, in fact, are likely to arise suspicion.
To solve this problem, it has been studied a modification to the JPEG algorithm that inserts LSBs in some of the lossless stages or pilots the rounding of the coefficients of the DCT used to compress the image to encode the bits. Since we need to have small image file sizes, we should resort in using 8-bit images if we want to communicate using LSB insertion, because their size is more likely to be considered as normal.
The problem with 256 colors images is that they make use of an indexed palette, and changing a LSB means that we switch a pixel from a position to an adjacent one. If there are adjacent contrasting colors in the palette, it can happen that a pixel in the image changes its color abruptly and the hidden message becomes visible.
To solve this problem different methods have been studied, like rearranging the palette so that adjacent colors donâ„¢t contrast so much, or even reducing the palette to a smaller number of colors and replicating the same entry in the table in adjacent positions, so that the difference after the embedding of the message is not visible at all. Moreover for most images the reduction of colors from, for instance, 256 to 32 is hardly visible.
Most of the experts, anyway, advise to use 8-bit grayscale images, since their palette is much less varying than the color one, so LSB insertion is going to be very hard to detect by the human eye.
We point out this technique as an example for spread spectrum data-hiding methods. Spread spectrum techniques are now widely used in military radio communications, due to their very high robustness to detection and extraction.
SSIS is a quite mature process, and its aim is to achieve low detectability, ease of extraction, high data rate and good robustness to removal. It is based on spread spectrum techniques, but it enhances them by adding other encoding steps, acquiring better performance.
Technique basics
The core of SSIS is a spread spectrum encoder. These devices work by modulating a narrow band signal over a carrier. The carrierâ„¢s frequency is continually shifted using a pseudorandom noise generator fed with a secret key. In this way the spectral energy of the signal is spread over a wide band, thus decreasing its density, usually under the noise level.
To extract the embedded message, the receiver must use the same key and noise generator to tune on the right frequencies and demodulate the original signal. A casual observer wonâ„¢t be able even to detect the hidden communication, since it is under the noise level.
Data Rate
The data rate for this technique can be fairly high, but it depends on the choices made for the different parameters of the encoding. We can assume that the message will be compressed before embedding to allow for a higher capacity. The ECC encoder instead is going to insert redundant data into the stream to be able to correct the errors. The more errors we want to correct, the more bits will be added. Then, we have a tradeoff between good retrieval and capacity. If we can allow for small glitches in the recovered message, then we can use a weaker encoding.
Moreover, the more data we want to insert in the image, the more noise we are going to add to it. Then, if our cover is not noisy, we will be able to hide very little data, while if we choose a noisy one, its capacity will be higher. Experiments with 512x512 grey scale images (256 KB) could embed from 500 bytes to 5KB, depending on the cover. These experiments used a spread spectrum signal powerful enough to give almost total error-free retrieval, because the compression method adopted didnâ„¢t allow for any errors. This means a data rate varying from 1 hidden-bytes/50 cover-bytes to 10 hidden-bytes/50 cover-bytes, a rate surpassed only by LSB insertion.
Spread spectrum techniques are usually quite robust. Every transformation that adds noise to the image isnâ„¢t able to destroy the message. Anyway, a determined attacker can quite easily compromise the embedded data using some digital processing, like for example noise reduction filters, the same that are used in decoding to estimate the original cover.
Ease of detection/extraction
Spread spectrum encoding is widely used in military communications for its robustness against detection. An attacker canâ„¢t usually even know if the message was embedded, and anyway it will be very hard for him to extract it without knowing the right key2 and key3.
Suitability for steganography or watermarking
Due to its fairly high capacity and low ease of detection and extraction, SISS is very good for steganography.
Problems and possible solutions
The basic tradeoff in using SSIS is between the error rate we can afford and the amount of informations we want to embed, that varies in turn the power of the added noise. The ECC is used to allow for a lower power without increasing the Bit Error Rate as well.
Further improvements will deal with improving the original cover estimate stage, so that itâ„¢ll lead to a lower Bit Error Rate in the recovered signal, allowing to use less redundant ECCs.
The first is redundant encoding by dividing the cover into blocks, and embedding the same message in each of them, so that the hidden data can be extracted even from a part of the image as big as one block, but the more of it we have, the more certain we can be about the result.
Moreover, they added to the spectrum a template that can, through a log-polar transform applied to the spectrum of the stego-image, determine the original scale factor and orientation of the image, rendering the stego-message virtually immune to scaling and rotation.
Finally, spread spectrum techniques can add an adaptive perceptual masking filter before the insertion of the signal, so that the added noise is quite sure to be under perceptual limits. This, however, will increase the error rate in the retrieval, because it reduces the power of the embedded signal.
In this paper we tried to give an all-round view of steganography, both used to exchange messages and watermarking. First we gave an outline of the problem, telling also some of the history of this quickly developing field.
Then we showed the different techniques invented, from the simplest to the more complex ones, trying to evaluate them under many points of view. Major emphasis was put on data hiding in images, for the techniques involved are usually more mature than the corresponding ones for other kinds of informations. Image encoding algorithms can also be representative for manipulation of other types of media like voice, text, binary files, binary files, communication channels etc.
Then we gave an outline of the problems involved with watermarking, a field that has come into light after the development of broadband worldwide digital networks.
Steganography and digital watermarking are undergoing a development process similar to that of encryption. Steganographyâ„¢s niche in security is to supplement cryptography and not to replace it. There is a continuous invention of new techniques for steganography followed by successful breakings and new improvements of them.
Neil F. Johnson, Sushil Jajodia, George Mason University, "Exploring Steganography: Seeing the Unseen", IEEE Computers, February 1998, pp. 26-34
W. Bender, D. Gruhl, N. Morimoto, A. Lu, "Techniques for Data Hiding" IBM Systems Journal, Vol. 35
Ross Anderson, Roger Needham, Adi Shamir, "The Steganographic File System", 2nd Information Hiding Workshop, 1998
Ross J. Anderson, Fabien A.P. Petitcolas, "On the limits of steganography"
Steganography comes from the Greek and literally means, "Covered writing". It is one of various data hiding techniques, which aims at transmitting a message on a channel where some other kind of information is already being transmitted. This distinguishes steganography from covert channel techniques, which instead of trying to transmit data between two entities that were unconnected before.
The goal of steganography is to hide messages inside other harmless messages in a way that does not allow any enemy to even detect that there is a second secret message present. The only missing information for the enemy is the short easily exchangeable random number sequence, the secret key, without the secret key, the enemy should not have the slightest chance of even becoming suspicious that on an observed communication channel, hidden communication might take place.
Steganography is closely related to the problem of hidden channels in secure operating system design, a term which refers to all communication paths that cannot easily be restricted by access control mechanisms. In an ideal world we would all be able to sent openly encrypted mail or files to each other with no fear of reprisals. However there are often cases when this is possible, either because the working company does not allow encrypted email or the local government does not approve of encrypt communication. This is where steganography can come into play.
1. Introduction
2. Steganography and Cryptography
3. A brief history of steganography
4. Some definitions
5. Basic methods behind steganography
6. Image Files
6.1. File compression
6.2. Embedding data
7. Concealment in digital images
7.1. LSB insertion
7.2. Masking and filtering
7.3. Algorithms and transformations
8. Least Significant Bit insertion
8.1. Technique basics
8.2. Data rate
8.3. Robustness
8.4. Ease of detection/extraction
8.5. Suitability for steganography
9. Spread Spectrum Image Steganography
9.1. Technique basics
9.2. Data rate
9.3. Robustness
9.4. Ease of detection/extraction
9.5. Suitability for steganography
10. Conclusion
11. Reference
please read for seminar information about Cryptography and Steganography , its amazing
Post: #3
really nice inforamtion any ways thanks..for posting.. i need code for dis project
Post: #4
please read this article also http://www.sansreading_room/whitepapers/...future_552 am sure it should be a benefit to learn more about stenography
Post: #5

.docx  template.docx (Size: 44.36 KB / Downloads: 275)


According to my study I propose a new steganography method based on image layers. The proposed method divides the host image into blocks and embeds the corresponding secret data bits into each block using the layers generated by the binary representation of pixel values. Based on a secret bit sequence ,the system performs a search on the rows and columns of the layers for finding the most similar row or column and the location of row or column and its differences from the secret data will be marked by modifying minimal number of bits in the LSB of the blocks. In the experiments, randomly selected secret messages are embedded into several different images. The performance of the proposed method against steganalysis techniques is evaluated using the measure of distorted pixels.
Post: #6

.pdf  Proposal_stego1.pdf (Size: 50.02 KB / Downloads: 315)
steganography full report

Kathryn Hempstalk
March 24, 2005
Supervisor: Eibe Frank

Steganography is the art and science of writing hidden messages in such a way
that no one apart from the intended recipient knows the existence of the
message.1 Recently, many digital techniques have been developed that perform
steganography on electronic media, most notably sound and image files. The
outcome of this project is to create a cross-platform tool that can effectively hide
a message inside a digital image file.
Post: #7
Steganography includes a vast array of techniques for hiding messages in a variety of media. Among these methods are invisible inks, microdots, digital signatures, covert channels and spread-spectrum communications. Today, thanks to modern technology, steganography is used on text, images, sound, signals, and more. The advantage of steganography is that it can be used to secretly transmit messages without the fact of the transmission being discovered. Often, using encryption might identify the sender or receiver as somebody with something to hide. For example, that picture of your cat could conceal the plans for your company's latest technical innovation.
However, steganography has a number of disadvantages as well. Unlike encryption, it generally requires a lot of overhead to hide a relatively few bits of information. However, there are ways around this. Also, once a steganographic system is discovered, it is rendered useless. This problem, too, can be overcome if the hidden data depends on some sort of key for its insertion and extraction.
In fact, it is common practice to encrypt the hidden message before placing it in the cover message. However, it should be noted that the hidden message does not need to be encrypted to qualify as steganography. The message itself can be in plain English and still be a hidden message. However, most steganographers like the extra layer of protection that encryption provides. If your hidden message is found, and then at least make it as protected as possible.
Methods for hiding data in three varied media (text, image, and audio) will be described, and some guidelines for users of steganography will be provided where necessary. In addition, we will take a brief look at steganalysis, the science of detecting steganography, and destroying it. In the field of steganography, some terminology has developed.
The adjectives cover, embedded and stego were defined at the Information Hiding Workshop held in Cambridge, England. The term ``cover'' is used to describe the original, innocent message, data, audio, still, video and so on. When referring to audio signal steganography, the cover signal is sometimes called the ``host'' signal.
The information to be hidden in the cover data is known as the ``embedded'' data. The ``stego'' data is the data containing both the cover signal and the ``embedded'' information. Logically, the processing of putting the hidden or embedded data, into the cover data, is sometimes known as embedding. Occasionally, especially when referring to image steganography, the cover image is known as the container.

Steganography under Various Media
Often, although it is not necessary, the hidden messages will be encrypted. This meets a requirement posed by the ``Kerckhoff principle'' in cryptography. This principle states that the security of the system has to be based on the assumption that the enemy has full knowledge of the design and implementation details of the steganographic system. The only missing information for the enemy is a short, easily exchangeable random number sequence, the secret key. Without this secret key, the enemy should not have the chance to even suspect that on an observed communication channel, hidden communication is taking place. Most of the software that we will discuss later meets this principle.
Post: #8

.doc  Project Report.doc (Size: 87 KB / Downloads: 405)
steganography full report

1. Introduction

Digital multimedia data provides a robust and easy editing and modifying of data. The data can be delivered over computer networks with little to no errors and often without interference.

Unfortunately, digital media distribution raises a concern for digital content owners. Digital data can be copied without any loss in quality and content. This poses a big problem for the protection of intellectual property rights of copyright owners. Watermarking is a solution to the problem. It can be defined as embedding digital data, such as information about the owner, recipient, and access level, without being detectable in the host multimedia data.

Steganography relies on hiding covert message in unsuspected multimedia data and is generally used in secret communication between acknowledged parties. Steganography is a method of encryption that hides data among the bits of a cover file, such as a graphic or an audio file. The technique replaces unused or insignificant bits with the secret data. Steganography is not as robust to attacks since the embedded data is vulnerable to destruction.

Watermarking has the feature of robustness against attacks. Even if the existence and method of embedding the data is known, it may be difficult to destroy the hidden data.

Data hiding and data embedding can be classified as methods between steganography and watermarking.
Post: #9
Prepared by:IMRAN KHAN

.ppt  stegnography.ppt (Size: 385.71 KB / Downloads: 306)

What is steganography ?
Steganography is the branch of science .it is used for writing hidden messages in such a way that no one can able to read the message only the sender and receiver can read.

Steganography Terms
Carrier File – A file which has hidden information inside of it.
Steganalysis – The process of detecting hidden information inside of a file.
Stego-Medium – The medium in which the information is hidden.
Steganography – Modern Day
Steganography – Carrier Files

Steganography In Images
Steganography In Audio
Steganography In Video
Steganography In Documents

A steganograhy System

What is stegnograpy tool ?
With the help of stenography tool .we can see the hidden message inside the picture ,audio,documents etc.
Steganography Tools
Steganography Tools
S-Tools (GIF, JPEG)
StegHide (WAV, BMP)
Invisible Secrets (JPEG)
Many others…
Identification of hidden files

By identifying the existence of a hidden message, perhaps we can identify the tools used to hide it.
If we identify the tool, perhaps we can use that tool to extract the original message.

Post: #10

Khan, Mohammed Minhajuddin

What is Steganography?
Greek Words:
STEGANOS – “Covered”
GRAPHIE – “Writing”
Steganography is the art and science of writing hidden messages in such a way that no one apart from the intended recipient knows of the existence of the message.

This can be achieve by concealing the existence of information within seemingly harmless carriers or cover

Carrier: text, image, video, audio, etc.

Steganography, Cryptography, and Watermarking
There are two major branches of information hiding, Steganography and Watermarking

Communication in watermarking is the host signal, with the embedded data providing copyright protection.
The existence of a watermark is often declared openly.
Any attempt to remove or invalidate the embedded content renders the host useless.

Doesn’t conceal the communication.
Scrambles the data to prevent eavesdroppers understanding the content.
Cryptography involves various methods and implementations.
May be considered complementary and orthogonal (unrelated).

Once the presence of hidden information is revealed or even suspected, the purpose of steganography is defeated.

History of Steganography
Steganography ancient origins can be traced back to 440 BC, from the Histories of Herodotus

Demeratus sent a warning about a forthcoming attack to Greece by writing it on a wooden panel and covering it in wax.

Histiaeus, who shaved the head of his most trusted slave and tattooed a message on it. After his hair had grown the message was hidden. The purpose was to instigate a revolt against the Persians.

World War II

Invincible inks

Null ciphers (unencrypted messages):

Apparently neutral's protest is thoroughly discounted and ignored. Isman hard hit. Blockade issue affects pretext for embargo on by products, ejecting suets and vegetable oils.

Sent by a German Spy in WWII, by taking the second letter in each word the following message emerges:
Pershing sails from NY June 1.

Microdot Technology
Shrinking messages down to the size of a dot became a popular method. Since the microdot could be placed at the end of a sentence or above a j or an i.

Modern Steganography Techniques
Masking and Filtering: Is where information is hidden inside of a image using digital watermarks that include information such as copyright, ownership, or licenses. The purpose is different from traditional steganography since it is adding an attribute to the cover image thus extending the amount of information presented.

Algorithms and Transformations: This technique hides data in mathematical functions that are often used in compression algorithms. The idea of this method is to hide the secret message in the data bits in the least significant coefficients.

Least Significant Bit Insertion: The most common and popular method of modern day steganography is to make use of the LSB of a picture’s pixel information. Thus the overall image distortion is kept to a minimum while the message is spaced out over the pixels in the images. This technique works best when the image file is larger then the message file and if the image is grayscale.

Important Requirement for Steganographic System

Security of the hidden communication

size of the payload

Robustness against malicious and unintentional attacks

Detection of Steganographic Content/Countermeasures

The detection of steganographically encoded packages is called Steganalysis.

Visual Analysis tries to reveal the presence of secret communication through inspection, either with the naked eye or with the assistance of a computer.

Statistical (Algorithmic) Analysis reveals tiny alterations in an image's statistical behavior caused by steganographic embedding.

The nominally universal methods developed to detect embedded stego-data are generally less effective than the steganalytic methods aimed at specific types of embedding.

for more:

Post: #11
please send the seminar report on stegnography
Post: #12
Steganography is the art and science of writing hidden messages in such a way that no one apart from the intended recipient knows of the existence of the message; this is in contrast to cryptography, where the existence of the message itself is not disguised, but the content is obscured. It is really very important.
Post: #13
presented by:
Heema Jain

.pptx  Heema Jain-steganography.pptx (Size: 1.59 MB / Downloads: 176)
STEGANOGRAPHY -Security Through Obscurity

• Steganography - \Steg`a*nog"ra*phy\,
[Greek steganos (covered or secret) + graphy (writing or drawing).]
• Steganography is the art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message, a form of SECURITY THROUGH OBSCURITY.
• Steganography includes the concealment of information within computer files. In digital steganography, electronic communications may include steganographic coding inside of a transport layer, such as a document file, image file, program or protocol
 Both are used as means to protect information .
 Cryptographic techniques "scramble" messages so if intercepted, the messages cannot be understood .
 Steganography,"camouflages" a message to hide its existence and make it seem "invisible" thus concealing the fact that a message is being sent altogether.
 The advantage of steganography, over cryptography alone, is that messages do not attract attention to themselves or arouse suspicion. Therefore, whereas cryptography protects the contents of a message, steganography can be said to protect both messages and communicating parties.
 Hidden messages within wax tablets: in ancient Greece, people wrote messages on the wood, then covered it with wax upon which an innocent covering message was written.
 Hidden messages on messenger's body: also used in ancient Greece. Herodutus tells the story of a message tatooed on a slave's shaved head, hidden by the growth of his hair, and exposed by shaving his head again. The message allegedly carried a warning to Greece about Persian invansion plan. This method has obvious drawbacks, such as delayed transmission while waiting for the slave's hair to grow, and the restrictions on the number and size of messages that can be encoded on one person's scalp.
 The milk of thithymallus plant is dried to transparency when applied to paper but darkened to brown when subsequently heated .
 In WWII, the French Resistance sent some messages written on the backs of couriers using invisible ink. Common sources for invisible inks are milk, vinegar and fruit juices.
 With the advent of photography, microfilm was created as a way to store a large amount of information in a very small space. In both world wars, the Germans used "microdots" to hide information. A secret message was photographed, reduced to the size of a printed period, then pasted into an innocuous cover message, magazine, or newspaper.
 Modern steganography entered the world in 1985 with the advent of the personal computer being applied to classical steganography problems.
 What to hide
– Texts
– Images
– Sound
 Hide or embed
– text in text/images/sound files
– image in image/sound files
– sound in sound files
Post: #14
Steganography comes from the Greek and literally means, “Covered writing”. It is one of various data hiding techniques, which aims at transmitting a message on a channel where some other kind of information is already being transmitted. This distinguishes steganography from covert channel techniques, which instead of trying to transmit data between two entities that were unconnected before.
The goal of steganography is to hide messages inside other “harmless” messages in a way that does not allow any “enemy” to even detect that there is a second secret message present. The only missing information for the “enemy” is the short easily exchangeable random number sequence, the secret key, without the secret key, the “enemy” should not have the slightest chance of even becoming suspicious that on an observed communication channel, hidden communication might take place.
Steganography is closely related to the problem of “hidden channels” n secure operating system design, a term which refers to all communication paths that cannot easily be restricted by access control mechanisms. In an ideal world we would all be able to sent openly encrypted mail or files to each other with no fear of reprisals. However there are often cases when this is possible, either because the working company does not allow encrypted email or the local government does not approve of encrypt communication (a reality in some parts of the world).
Post: #15

.ppt  STEGANOGRAPHY.ppt (Size: 62.5 KB / Downloads: 174)
• Protection of digital media.
• Privacy of information transmitted across the world wide web.
• To make the transmitted information invisible by embedding the information in a cover media.
• We try to enhance the security and the robustness of the information against attacks and image processing techniques

• Steganography is the practice of hiding private or sensitive information within something that appears to be nothing out of the usual.
• Steganography in the modern day sense of the word usually refers to information or a file that has been concealed inside a digital Picture Video or Audio file.
• Steganography terms
• A Original message or a file in which hidden information will be stored inside of it
• The medium in which the information is hidden
• Embedded or Payload– The information which is to be hidden or concealed.
• Steganalysis– The process of detecting hidden information inside a file
• Introduction:
• Advance security is not maintained by the password protection but it is gained by hiding the existence of the data which can only be done by Steganography
• Steganography is a subject which is rarely touched upon by most IT Security Enthusiasts
• Steganographic Systems can hide messages inside of Digital Objects such as a file that has been concealed inside a Digital Picture, Videoor Audio file.
• The main advantage of Steganography is it hides the information in such a way that there is no information hidden at all
• This is derived from the name of lizard “Stegosaurs”.
Steganography Basics
• The word steganography comes from the Greek steganos , meaning covered or secret, and graphy , meaning writing or drawing. Therefore, steganography literally means covered writing.
• Steganography simply takes one piece of information and hides it within another
– Computer files (images, sounds recordings, even disks) contain unused or insignificant areas of data
– Steganography takes advantage of these areas, replacing them with information (encrypted mail, for instance).
– The files can then be exchanged without anyone knowing what really lies inside of them
– An image of the space shuttle landing might contain a private letter to a friend.
– Rumor has it that terrorists used steganography to transmit messages to one another
Steganography Early Examples
In his history of the Persian Wars, Herodotus tells of a messenger who shaved his head and allowed a secret message to be tattooed on his scalp. He waited until his hair grew back. Then he journeyed to where the recipient awaited him and shaved his head again. The message was revealed. It was history’s first use of steganography.
Steganography Invisible Ink
Ancient Romans used to write between lines using invisible ink based on various natural substances such as fruit juices, urine, and milk. Their experience was not forgotten: even nowadays children play spies and write secret messages that appear only when heated.
Application of Steganography
• To hide a message intended for later retrieval
• Copyright marking-digital watermarking and fingerprinting
Types of Steganography carriers
• Image files as carriers
– using 24-bit images: too large to pass over the network
– using 8-bit images: prone to modification/ lossy compression
• Audio files as carriers
– Exploits imperfection of human auditory system called audio masking.
– In this case, weak signal is generally inaudible in loud signal.
• Video files as carriers
– A combination of sound and image techniques can be used
• Text files as carriers
– Uses open space in text files to encode the secret information. It works on the fact that to a casual reader an extra space anywhere does not prompt abnormality.
– Disadvantage is that it requires large amount of data to conceal little information
• DNA strands as carriers
Steganography using image files
• Common approaches to image steganography is:
– Least significant bit insertion
– Masking and filtering
– Algorithms and transformation
• LSB Technique
Based on three factors:
- large file size
- presence of ‘noise’
- the frailties of human perception
• Example of Steganography: Bit Plane Methods
Audio Steganography
-Human Auditory system operates over wide range of dynamic frequencies but is poor with regards to its differential range.
-loud sound masks the softer one.
Ways to hide data in audio
1.Low bit encoding replaces LSB of data in each sampling point with a coded binary string
2.Phase encoding substitutes the phase of an initial audio segment with a reference to the phase that represents the data.
-the phase of subsequent segments is adjusted in order to preserve the relative phase between segments
-more complicated than low-bit
3. Spread spectrum spreads the encoded data across as much of the frequency spectrum as possible.
- Data is encoded as a binary sequence which sounds like noise but which can be recognised by a receiver with the correct key.
- Spread spectrum techniques can be used for watermarking by matching the narrow bandwidth of theembedded data to the large bandwidth of the medium.
- Makes it difficult for an adversary to reconstruct the pseudo random signal used to spread data across freq range
4. Echo data hiding embeds data into a host signal by introducing an echo. The data are hidden by varying 3 parameters of echo:
– initial amplitude
– Decay rate
– offset
- The echo blends as the echo between the original and the echo decreases. The echo is perceived as the original sound.’
Steganography Principles
• Computer Steganography is based on two principles.
– The first one is that the files containing digitized images or sound can be altered to a certain extend without loosing their functionality.
– The other principle deals with the human inability to distinguish minor changes in image color or sound quality, which is especially easy to make use of in objects that contain redundant information, be it 16-bit sound, 8-bit or even better 24-bit image. The value of the least significant bit of the pixel color won’t result in any perceivable change of that color.
Steganography Process
• The data to be concealed is compressed and hidden within another file.
• The first step is to find a file which will be used to hide the message (also called a carrier or a container.)
• The next step is to embed the message one wants to hide within the carrier using a steganographic technique.
• Two different techniques commonly used for embedding are:
– Replace the least significant bit of each byte in the [carrier] with a single bit for the hidden message.
– Select certain bytes in which to embed the message using a random number generator; resampling the bytes to pixel mapping to preserve color scheme, in the case of an image...; hiding information in the coefficients of the discrete cosine, fractal or wavelet transform of an image; and applying mimic functions that adapt bit pattern to a given statistical distribution.
Steganography Software
• EZStego (Stego Online, Stego Shareware, Romana Machado)
– Java based software program which supports only GIF and PICT formats;
• Gif-It-Up v1.0 (Lee Nelson)
– A stego program for Windows 95 that hides data in GIF files
• Hide and Seek (Colin Maroney)
– can hide any data into GIF images;
• JPEG-JSTEG (Derek Upham)
– can hide data inside a JPEG file
• MP3Stego (Fabien A.P. Petitcolas, Computer Laboratory, University of Cambridge)
– can hide data inside MP3 sound files;
• Steganos (Demcom, Frankfurt, Germany)
– encrypts files and then hides them within BMP, DIB, VOC, WAV, ASCII and HTML files
Steganography Software

• S-Tools is one of the most popular steganography tools.
– This program is Windows 95/98 compatible
– It has the ability to conceal files within BMP, GIF and WAV files.
– Allows you to simply point and click your way to hiding files.
– It also has the ability to hide multiple files in one container.
– It has been updated each year and can be easily downloaded by anyone.
Steganalysis Basics
• Steganalysis is the art of discovering and rendering useless such covert messages.
• Steganalysis involves analysis of the carrier file
– Simpler steganographic techniques produce some discernible change in the file size, statistics or both.
– These changes can manifest themselves in color variations, loss of resolution and other distortions that are visible to the human eye.
– This form of detection requires that you know what the original carrier image or file should look like.
Detection of Steganographic Content/Countermeasures
The detection of steganographically encoded packages is called Steganalysis.
– Visual Analysis tries to reveal the presence of secret communication through inspection, either with the naked eye or with the assistance of a computer.
– Statistical (Algorithmic) Analysis reveals tiny alterations in an image's statistical behavior caused by steganographic embedding.
• The nominally universal methods developed to detect embedded stego-data are generally less effective than the steganalytic methods aimed at specific types of embedding.
• It is used in the way of hiding not the Information but the password to reach that Information.
• Difficult to detect .Only receiver can detect.
• Can be applied differently in digital image, audio & video file.
• It can be done faster with the large no of software's.
• Huge number of data = huge file size, so some one can suspect about it.
• In sending and receiving information can be leaked.
• The confidentiality of information is maintained by the algorithms, and if the algorithms are known then its all over.
• If this technique is gone in the wrong hands like hackers, terrorist ,criminals then this can be very much dangerous for all.
As steganography becomes more widely used in computing there are issues that need to be resolved. Many currently used techniques are not robust enough to prevent detection and removal of embedded data.
For a system to be considered robust, it should have the following properties:
• The quality of the media should not noticeably degrade upon addition of a mark.
• Marks should be undetectable without secret knowledge, typically the key
• If multiple marks are present they should not interfere with each other

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