Cloud computing has been defined as a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources that can be rapidly provisioned and released with minimal management effort or service provider interaction. But there is a risk of widespread data loss or downtime due to internet connectivity problems or a localized component failure in a cloud computing environment. In order to reduce the service availability risk or loss of data, a multi cloud system where data is replicated into multiple clouds offered by different cloud providers are used. Once the assets are in the cloud, the clients lose control over them, as data in the cloud typically resides in a shared environment. With the growth of a large number of cloud service providers, there is a need to protect confidential images stored in the cloud from unauthorized users and also from the cloud service providers. This paper proposes an integrated encryption scheme based on DNA sequences and scrambling using zigzag pattern or Magic Square of doubly even order pattern to ensure double-fold security for the secure storage of confidential images on multi-cloud.
2. DEFINITIONS FOR THE PROPOSED SYSTEM
2.1. Cryptosystem : A cryptosystem is a five tuple (M, C, , , D) where
i. M is a finite set of plain-text (images).
ii. C is a finite set of possible cipher-text.
iii. is a finite set of possible keys.
iv. For each K , there is an encryption rule, EK and a corresponding decryption rule, DK D.
Each EK : M C and DK : C M are functions such that DK (EK (x)) = x, for every plain-text x M.
2.2. Synthesis: Creation of DNA sequences for the image data is referred to as Synthesis. DNA sequences are made up of four bases – A, C, T and G. According to the DNA Digital Coding Technology , C denotes 00, A – 01, T - 10 and G – 11.
2.3. Translation: When the positions of sequences are translated, the sequences are interchanged.
2.4. Substitution: Each quadruple nucleotide sequence is substituted by the value returned by the DNA Sequence Crypt function.
2.5. Detect: Detect searches for a quadruple nucleotide sequence of the image starting from a random position in the DNA sequence file and returns true if a match is found and false otherwise.
2.6. DNA Sequence Crypt function: A DNA Sequence Crypt function is a one-to-many function d(x) that returns one of the many positions of the quadruple DNA sequence in the key DNA sequence file.
2.7. Rev-Synthesis: Rev-synthesis is the process of converting each sequence into its digital form.
2.8. Magic Square: A magic square of order n is a square matrix or array of n2 numbers such that the sum of the elements of each row and column, as well as the main diagonals, is the same number, called the magic constant, (M). Figure 1 displays magic squares of order 8 arranged in eight...