cryptography

cryptography

Synopsis

The system deals with security during transmission of data. Commonly used technology is cryptography. This system deals with implementing security-using steganography.
In this technology, the end user identifies an image which is going to act as the carrier of data. The data file is also selected and then to achieve greater speed of transmission the data file and image file are compressed and sent. Prior to this the data is embedded into the image and then sent. The image if hacked or interpreted by a third party user will open up in any image previewer but not displaying the data. This protects the data from being invisible and hence be secure during transmission. The user in the receiving end uses another piece of code to retrieve the data from the image.
Steganography is the art and science of hiding that communication is happening. Classical steganography systems depend on keeping the encoding system secret, but modern steganography is detectable only if secret information is known, e.g. a secret key. Because of their invasive nature, steganography systems leave detectable traces within a medium’s characteristics. This allows an eavesdropper to detect media that has been modified, revealing that secret communication is taking place. Although the secrecy of the information is not degraded, its hidden nature is revealed, defeating the main purpose of Steganography.
For JPEG images, Outguess preserves statistics based on frequency counts. As a result, statistical tests based on frequency counts are unable to detect the presence of steganographic content. Before embedding data into an image, Outguess can determine the maximum message size that can be hidden while still being able to maintain statistics based on frequency counts.
Outguess uses generic iterators object to select which bits in the data should be modified. A seed can be used to modify the behavior of the iterator. It is embedded in the data along with the rest of the message. By altering the seed, OutGuess tries to find a sequence of bits that minimizes the number of changes in the data that have to be made.

Compression reduces the average code length used to represent the symbols of an alphabet. Symbols of the source alphabet which occur frequently are assigned with short length codes. The general strategy is to allow the code length to vary from character to character and to ensure that the frequently occurring character have shorter codes.
CRCSET is an anti-virus utility. Its purpose is to protect programs from third parties manipulation .CRC set is the most effective weapons against computer viruses. This the Cyclic Redundancy Check, or CRC, is an error-checking algorithm used in many types of computer operations, especially in data transfer.

Before transmitting the data, the utility want to calculate the CRC value and attach with data. In receiving end, the CRC is recalculated and based on that calculated value, it will specify the acceptance or rejection.

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