Data Security using Multi-Level Encryption

Dr Satish Garg

Govt. College for Girls Palwal (Kurukshetra) - 136131

ABSTRACT:

1. INTRODUCTION

With the swift development in communication technology and success of internet, it has become a reality to send any data around the globe in a fraction of second. But the security of data is very important and challenging issue in communications because there is always some risk that an intruder may intercept our data. So it is not safe to send confidential data from one node to another (a node may be a computer or a person). The confidential data may be bank statements, bank deals, military information, confidential data of companies, our passwords etc. Hence the data should be protected from the intruder otherwise any massive disaster may happen all-on-a-sudden, which may be called as e- disaster[1,2]. In order to make safe and sound the system one should consider the security primary attributes such as confidentiality, integrity and availability, and secondary attributes such as authenticity, non-repudiation and accountability etc. There are a large number of techniques to achieve security goals, one of these is Cryptography. “Cryptography is the study of secret (crypto-) writing (-graphy) that is hiding the content of the message from the intruder so that the intruder may not be able to recover the original message” [3- 4]. “The cryptographic algorithm can be divided into two categories: (i) Symmetric Key Cryptography where a single key is used for both encryption and decryption purpose. (ii) Public Key Cryptography where two different keys are used - one for encryption and the other for decryption purpose”[3,4]. In the present paper the authors have introduced a unique symmetric key cryptographic technique where three modern cipher, namely transposition, rotation and XOR ciphers have been used.

In the proposed algorithm SKG 3.31 following steps are involved :

(i)                  Firstly, all the characters are converted in binary form using 8 bit ASCII Code

(ii)               Secondly, Transposition Cipher is used, where position of the bits obtained at step (i) are interchanged

(iii)            Rotation Cipher is applied, where position of the bits obtained at step (ii) are shifted towards Left or vice versa

(iv)            Thirdly, the bits obtained at step (iii) are superimposed on a continuous binary pulse in digital form using XOR Operation, which is reversible operation.

(v)               Finally, 8-bit ASCII Code is used to convert the bits obtained at step (iv) into corresponding characters and thus we get encrypted cipher text

II. ENCRYPTION ALGORITHM SKG 3.31:

1.         Read the input string of characters and Check the number of characters, N

2.         If N<10, then write Program is Not Applicable

3.         Convert characters into Binary Form using ASCII (8 bit) Code, we get 8N Bits

4.         If (8N+1)/N1 = 0, Transpose Integral Multiples of LMB with corresponding RMB upto 4N Bits otherwise proceed upto 8N Bits

5.         Rotate the string of bits in circular queue towards Left/Right by N2 places

6.         Generate a binary string of consecutive 0’s & 1’s such that number of consecutive 0 & 1 are from 1 to 7 and length of this binary string is 8 N

7.         Modulate string obtained at Step 5 on that obtained at Step 6 using XOR operation

8.         Convert binary string obtained at Step 7 into characters using ASCII (8 bit) Code, we get N Characters

9.         Output is Encrypted String i.e., Cipher Text

III. EXPLANATION OF ALGORITHM SKG 3.31 :

I.     All the steps mentioned in algorithm SKG 3.31 are explained below :

Step 1 : Step 1 requires to take input from any media in the form of characters and then it checks numbers of characters in that input which is denoted by N

Step 2 : This step checks the value of N which may be less than, equal to or more than 10, if value of N is less than 10 then this particular algorithm shall not be applicable

Step 3 : At this step, if value of N is not less than 10 then the string of input characters will be converted into binary form using ASCII (8-bit) Code. This conversion shall give 8N bits as output

Step 4 : In step 4, the desired mathematics is performed. If the achieved value is 0, then transposition operation shall stop at middle of binary string i.e., at 4Nth bit otherwise it shall be continue upto 8N bits

Step 5 : At this step, the binary string of 8 N Bits is rotated in circular queue by N1 places towards Left/Right or vice versa

Step 6 : In step 6, a binary string of 8 N Bits of consecutive 0’s & 1’s is generated such that number of consecutive 0’s & 1’s are from 1 to 7

Step 7 : In step 7, binary string obtained at step 5 is superimposed on binary string generated at step 6 using XOR operation Step 8 : The binary string obtained from the last mechanism is converted back into N characters using the same ASCII (8-bit) Code

Step 9 : The last step denotes the encrypted characters as desired output