One concepts of secret sharing, the secret image

One of the most popular form of communication network where multimedia content, financial documents and informations, confidential data such as military information distribution is a common practice. But anyone can view the information over the internet . Thus security of data and images is becoming more and more important in real life application. Thus the increasing demand of security needs to be fulfilled. For this purpose many tools are present out of which Visual Cryptography is the one. Naor and Shamir were he first to introduce it in 1979 for providing security and confidentiality for sharing secret visual information over an unsecured communiation channels. Using various concepts of secret sharing, the secret image is encrypted into number of shares with the help of an encryption procedure and then is distributed to various members of group or is distributed or transmitted over unsecure communication channels such that these shares can reveal information only when brought together.Adi Shamir and G. Blakley also proposed a seperate idea of secret sharing in 1979. Polynomial Interpolation of the basis of Shamir’s scheme. Hyper Plane Geometery is the basis of Blakley secret sharing scheme. Asmuth and Bloom also proposed a secret sharing scheme in 1983. Chinese emainder Theorem was the basis of their secret sharing scheme. There are many other methods to protect sensitive data in image out of which one is Steganography. In this method an innocent cover medium such as a digital image, video, audio, etc is used to hide a secret image. But this method has a weakness. The whole secret information is kept in a single cover medium and if this cover medium is somehow lost or corrupted then secret hidden data and information is also lost or corrupted. a method was proposed by Lin and Tsai in 2004 in which they used Steganography for generating meaningful shares with secret image sharing. Polynamial based secret sharing approach which was proposed by Shamir was also used by this scheme leading to very high complexities in computation.Since huan visual systems are used for decryption process, the secret information can be found out is person find outs atleast k number of shares. Thus insecutrity in simple visual cryptography highly increased 1.\
In this paper we will be using symmetric algorithm for the process of image encryption. A common cryptographic key also known as symmetric key is used by both sender and reciever ends for data transmission. Due to this it is also known as shared key cryptography. A key is a special information that helps the sender to convert the plain text to an encrypted form known as cipher text and helps the reciever to convert the cipher text back to plain text. Various type of encryption algorithms and secret keys are used to convert plain text to cipher text. The same operations are performed by the reciever side but in reverse order. The various algorithms for image encryption are chaotic, blowfish, AES algorithms etc 2. We are also using the concept of Binary Tree Data Structure. A Binary Tree is a Tree data structure in which each node has atmost two children. They are referred to as the left child and the right child. A binary tree has the advantages of both an ordered array and a linked list as searching is quick in a sorted array and insertion or deletion operations are fast in linked list.\
Some of the basic terminology used in any cryptosystem are as folows3:-\
1) $Plain Text$- The original message that can be easily read by humans. It is a term in cryptography that is used for a message before its encryption or after its decryption. For example, Alice is a person wishes to send “Hello Friend how are you” message to the person Bob. Here the plain text message is “Hello Friend how are you”.
\2) $Cipher Text$- In cryptography, encrypted data is known as cipher text. This text is unintelligible until it has been converted into the plain text with the help of a key. For example, “phqgiumealy” is a cipher text for plain text “abcdefghijk”.
\3) $Encryption$- It is security method or tool for computer network. The process of converting information ( plain text ) using a defined algorithm to make it unreadable ( cipher text ) to anyone except those containing special knowledge, usually known as a key is called Encrytpion. It is one of the most effective method to achieve security. Encryption is used to protect confidentiality of a message. For encryption, a secret key is used. Encrypted data is known as cipher text and decrypted data is known as plain text.
\4) $Decryption$- The process of taking encrypted or encoded text and converting it back to original text is called as Decrytpion. Decryption is used for un-encrypting the data with keys and algorithm and make it readable. Cryptography uses the decryption process at the receiver side to retrieve the original message from the non-readable message (Cipher Text). The decryption process requires two things – a Decryption algorithm and a secret key. A Decryption algorithm indicates the process that has been used in Decryption. The encryption and decryption algorithm are usually the same.
\5) $Key$- A key is a numeric value or alpha numeric text or may be a special symbol. The Key is used at the time of encryption on the plain text and at the time of decryption on the cipher text. The selection of key plays important role in cryptographic process as the security of encryption algorithm fully depends on it. For example, if Alice uses a key of 2 and an additive cyptosystem algorithm to encrypt the Plain Text “University” then Cipher Text produced will be “wpkxgtkva”.