Data Encryption: What is It

Data Encryption is the mechanism by which message is changed to form that cannot be read by the unauthorized user, known as ciphertext. Only user having a secret key can access the text message. The message before being sent without encryption is called plaintext. Two mechanisms of message encryptions are: Symmetric encryption, in which the same secret key known as private key is applied to encrypt the data by the sender and decrypt the data by the receiver. The secret key is common for sender and receiver. Asymmetric encryption uses two keys; private and public for encryption and decryption.

The mechanism of data encryption is to protect information from threats as it is stored on computers and transmitted using the internet or other computer networks. The following mechanism is used for changing the text into colors at the sender side: ASCII based encoding mechanism using color

The method of ASCII based encoding mechanism using colors is used by. In RGB 256 color style, a pixel is represented by 24 bits, in which 8 bits represent the intensity of each color. For instance, color (100, 125, 140) is represented as (01100100 01111101 10001100) and implemented by. Choosing the first eight bits i.e. 01100100: and ignoring the Most Significant Bit, the remaining 7 bits or first 128 parts of the color is used to represent a character in the ASCII table. Likewise, three different characters can be denoted by a single color. Thus, a text document is converted into an encoded file filled with colored dots. By using the above technique of encoding, huge quantity of text can be compressed and transmitted in a more secured way. Concept of ASCII based encoding method for representing characters and changing them into colors is used in the proposed study.

Lossless text compression

Text compression mechanism needs that the combination of compression and decompression mechanisms to be lossless, or else the data cannot be restored in actual format. The data compression through text substitution method is referred by. The scheme of data compression mechanisms includes adjustments among various factors, such as degree of compression, amount of distortion introduced; if using a lossy compression algorithm and the computational resources required to compress and uncompress data. The mechanism given below is used for lossless text compression in the Color Coded encryption at the source end implemented by Huffman:

Huffman Encoding Compression Algorithm

The Huffman encoding algorithm is an optimal compression algorithm in which the occurrence of each letter or symbol are used to compress the data. The idea behind the algorithm is that if you have some letters that are more frequent than others, it makes logic to use fewer bits to encode those letters than to encode the less repeated letters. This algorithm builds the bottom up tree using the occurrence of each letter or symbol.

First, every letter starts off as part of its own tree and trees are ordered by the occurrence of the letters in the actual string. Then the two least frequently used letters are combined into a single tree and the frequency of that tree is set to be the combined frequency of the two trees that it links together.

This new tree is reinserted into the record of trees in its sorted place. The process is then repeated, treating trees with more than one element the same as any other trees except that their frequencies are the sum of the frequencies of all of the letters at the leaves. This is just the sum of the left and right children of any node because each node stores the frequency information about its own children. The process completes when all of the trees have been combined into a single tree. This tree describes a Huffman compression encoding.

Generally tree is design from the bottom up manner: we start out with 256 trees and end up with a single tree with 256 leaves along with 255 internal nodes. The tree has interesting property: the occurrences of all of the internal nodes combined together will give the total number of bits needed to write the encoded file.